Volume 5, Issue 1

20 IT M M e!

SU id R Ins CDa CD 10 Dat

ollision C The International Compendium for Crash Research

Volume 5 Issue 1

Spring 2010

Common Post-impact Speed Analysis Effect of Directional Tires on Wet Traction

CDR Technology An Abbreviated History

WET or FROZEN

ACM Access Considerations

Rollover Crash Reconstruction A Variable Deceleration Rate Approach

Insurance Applications

For CDR Legal Considerations

3-D Simulation & ViSualization Since 1993

Expert AutoStats® Expert AutoStats® is a computer program containing over 40,000 vehicles cars, vans, utility vehicles, and light pickups. 1945-2010 model years are represented.

This program can be used alone or with our Expert Qwic Calcs® and Expert VIN DeCoder® programs. Also accessible from within REC-TEC.

4N6XPRT StifCalcs® 4N6XPRT StifCalcs puts the NHTSA Crash Test database on YOUR 32 bit MS-Windows computer PLUS calculates A-B-G values and Test Specific Crush Factors based on the NHTSA test data, with no need for you to get on the internet, all for the price of only $570.00*! Can you do this yourself “for free”?? Only if you value YOUR time at $0.00!!

(Laptop & Desktop IBM Compatible)

Enter:

Manufacturer and Year

Select:

Model from pop-up window

Output:

Wheelbase Overall Length Height Wt. Distrib

Curb Weight Width Drive Wheels Front/Rear Track

Mid-60's to present output also includes (when available): Front Overhang Rear Overhang Bumper Heights Hood Height Turning circle Wheel radius Bumper-to-Hood Bumper-to-Window

HVE Technology Timeline – Key DaTes 1996

EDC introduces HVE Version 1.0 and several integrated simulation modules (e.g., EDSMAC, EDVSM, EDSVS) to perform real-time 3-D vehicle crash simulation and visualization for the first time.

1998

EDC introduces EDSMAC4, an extended version of EDSMAC that simulates in a single run an entire crash sequence involving any number and any type of vehicles.

1999

EDC introduces SIMON ®, the first fully 3-D HVE-compatible simulation that visualizes in a single run any number and any type of vehicles with suspensions, steering systems, braking systems and drivetrains.

2004

EDC introduces DyMESH ®, the first fully 3-D collision simulation and visualization model integrated within HVE.

2011

EDC introduces HVE DamageStudio®, the first tool to allow users to correlate 3-D collision damage directly with the kinetics (force magnitude and direction), delta-V, acceleration and other important collision parameters.

Expert AutoStats® is currently owned by over 660 private individuals and 270 Law Enforcement agencies in the U.S.A., Canada, and South America. Additional information, brochure, and order from can be downloaded from:

Search for vehicles by entering Year, Make, and Model, or by any combination of: Length, Wheelbase, Weight, Body Style, Make, Model, and Impact location Print out data and stiffness for single tests, or a Test Summary Stiffness Report when more than one test meets your search criteria For more information, program order form, and sample printouts please visit our web site at http://www.4n6xprt.com. You may also call us at (619) 464-3478 M-F, 9a-5p (PST), if you have specific questions.

www.4n6xprt.com/4n6sc.htm

www.4n6xprt.com/4n6as.htm

PROGRAM ORDER FORM (Please Print) Contact Name: ________________________________________________ Company: ____________________________________________________ Street: ______________________________________________________ City:____________________ State:____ Zip:__ __ Country: __________ Phone: (_____) _______________ Fax: (_____) ___________________ E-Mail: ______________________________________________________ Expert AutoStats® 4N6XPRT BioMeknx™ Expert Qwic Calcs® 4N6XPRT Ped & Bike Calcs® 4N6XPRT StifCalcs® Expert VIN DeCoder® (pkg) Expert TireStuf® Order Processing

- C heck = $5.00 / C redit C ard = $10.00 / G ovt. P .O . = $15.00 N otarized Affidavit R equirement $25.00 per required N otarized Signature

www.edccorp.com/HVEtechnology

= ________ = ________ = ________ = ________ = ________ = ________ = ________

= _______ = _______

Q Deliver via electronic download (Email address Required) = 0.00 Q Ship on USB - $35.00 per disk per program = ______ California Sales Tax Enclosed is:

For the complete HVE Technology Timeline visit:

- $ 595.00 ea.

- $ 495.00 ea.

- $ 275.00 ea.

- $ 375.00 ea.

- $ 570.00 ea.

- $ 525.00 ea.

- $ 85.00 ea.

- 9.50%

TOTAL (U.S. Dollars)

= ________

= ________

V isa ___ M asterC ard ___ Am. Ex. ___ E xp ____/____ - C heck ___ - G vt PO ___

Card Number: _______________________________________________ Name on Card: _______________________________________________ Signature: ________________________________________________ Please Make Checks*/Purchase Orders Payable to:

4N6XPRT Systems®

8387 University Ave - La Mesa, CA 91941-3842 - U.S.A. FAX: (619) 464-2206 Phone: (619) 464-3478 Web: http://www.4n6xprt.com

Engineering Dynamics Corporation 8625 SW Cascade Ave., Suite 200 Beaverton, OR 97008 USA (503) 644-4500 • www.edccorp.com COL-SP11

Knowledge = Power

Checks *MUST* be drawn on a U.S. bank. Orders are shipped within 10 working days of receipt.

Prices subject to change without notice.

Multiple orders and Package discounts available. Please call for details.

Contents Contents

SPRING 2010

of interest ofMyinterest 10 Turn at the Wheel

12 10 “Gear-Up!” Calendar of Events 8 My Turn at the Wheel 12 “Gear-Up!” 16 Effect Of Directional Tires On Wet Traction

features features

- H. J. Herzlich, Robert Swint, Ritsch B. Unser 16 Edward Effect Ofand Directional Tires

Onor Wet Traction 28 wet frozen acm access - H. J. Herzlich, Robert Swint, considerations Edward Ritsch and B. Unser - Sean Haight

28 Insurance wet or frozen acm access 36 Applications for Crash considerations Data Retrieval, Legal Considerations

28

28

- Sean Haight - Michael Merolli, David Brink, Patrick Conran, and Garcia-Vieux 36 Jasmine Insurance Applications for Crash

Data Retrieval, Legal Considerations 44 CDR Evidence Suppressed by Michael Merolli, David Brink, Patrick Conran, Oklahoma Court

50 50

and Jasmine - George Hall Garcia-Vieux

44 AnCDR EvidenceHistory Suppressed 50 Abbreviated of by Oklahoma Court CDR Technology - George Hall - Rusty Haight

50 A Variable An Abbreviated History of 74 Deceleration Rate CDR Technology Approach to Rollover Crash - Rusty Haight Reconstruction Rose 74 - Nathan A Variable Deceleration Rate Approachand to Rollover Crash 84 Retrieving Interpreting Data Reconstruction from Ford Powertrain Control Mod- Nathan Rose ules using the Bosch Crash Data Retrieval Tool 84 - Bruce Retrieving and Interpreting Data McNally from Ford Powertrain Control 96 Common Post Impact Modules using the Speed BoschAnalysis Crash - Greg Russell Data Retrieval Tool - Bruce McNally 104 EDR Module Types and in 96 Collision CommonData PostAvailable Impact Speed Analysis CDR Supported Vehicles - Greg Russell - Chuck Veppert and David Little

104 EDR Module Types and Collision Data Available in CDR Supported Vehicles - Chuck Veppert and David Little

74 74

96 96

fromtheeditor Volume 5, it’s hard to imagine we are already into our 5th year of publication. There have been so many changes and improvements with Collision and in our industry it is difficult to try to capture them in a single paragraph or letter but this issue’s cover really sums it up with a compilation of just some of the many pages from past issues represented. We can look forward to more improvements and advances in the coming months and years; particularly as it relates to the main topic of this issue: crash data.

Another area we are improving on is the web site for Collision (www.collisionpublishing.com). This year we launched a completely new web site with the goal in mind of more information and ease of use. Each issue of Collision now has it's own page with a custom slide show profiling many of that issue's articles. It also details what is in each of the back issues. Going forward we will be implementing a customer portal that will allow you to manage your subscription and view your account status directly online.

As has been our practice since Volume 1, Issue 1, one issue is typically dedicated to the proceedings of the CDR User’s Summit (formerly known as the CDR User’s Conference). This issue, Volume 5, issue 1, is no different.

As I look back at the past years, the quantity, depth and quality of the information presented at the Summit as well as in this follow-on issue of Collision continues to improve. A quick review of the index of this issue makes that clear.

So where do we go from here? As NAPARS President Chuck Veppert points out in his “Letter from the President” in this issue, the public perception of the “black box” in passenger cars, light trucks and SUVs has changed drastically over the last several months. Where there was once a commonly held misconception that these were “spies riding shotgun,” today, the perception has swung 180 degreea to where the technology has been largely embraced by the driving public and even many corners of the popular news media. Another indication of where “CDR Technology” is going can be found in the announcements at this year’s CDR User’s Summit.

This year, Bosch reported that, while the names of the OEs can’t be announced yet, several new auto manufacturers look to have their vehicle’s EDR inclusive systems supported for access by the Bosch CDR System within the coming year to 18 months. While there have been similar announcements in the past, all indications are that as a function of recent news accounts of “black box” technology and the soon to be effective NHTSA regulation (49CFR563), more manufacturers are, in fact, moving forward at a fairly fast clip to get “on board" with CDR. What does that mean for you? Check this issue’s articles on the suppression of CDR based data in Oklahoma, the history of the development of the CDR technology and a review of “which cars have which module and what kind of data does one expect to find?” and you’ll see that this is a fast moving, reading intensive undertaking and Collision is right there in the middle of it and you should be, too. In the coming months, the CDR program will be evolving, there will be new OEs supported and it’s up to each of us to find ways to keep abreast of the changes and, as we have for the last 4 years, Collision will be there to help keep the practicing reconstructionist up to date!

Managing Editor

Collision Publishing LLC PO Box 3383 Kirkland, WA 98083-3383 Toll Free: 800-280-7940 Email: editor@collisionpublishing.com Web: www.collisionpublishing.com ISSN: 1934-8681

The Collision Publishing media kit, including demographics, advertising rates, placement and sizes, is available online at: www.collisionpublishing.com

Advertiser Index

Collision Staff Scott Baker Sean Haight Tonya Baker Carla McLeod

Adverstising Rates & Information

Owner, Managing Editor Senior Editor Advertising Manager Subscription Services

CDR Summit Conference CD Included with this issue of Collision is the 2010 CDR User's Summit CD. This CD includes the speaker Power Point presentations and any additional supporting data.

Engineering Dynamics Corp. ........... Inside Front ARAS 360 ........................................ Page 1 MapScenes ....................................... Page 2 Collision Safety Institute .................. Page 14 Collision Magazine ........................... Page 15 Visual Statement ............................... Page 26-27

All rights reserved, © 2006-10 Collision Publishing LLC. The opinions and conclusions expressed in this publication and attached data disk and throughout the articles attributed to specific authors are the opinions and conclusions of the authors noted and not necessarily the editorial staff or anyone else for that matter.

While some articles have been reviewed for content, the accuracy of reprinted models or equations cannot be fully guaranteed. It is the responsibility of the reader to apply critical thinking to an individual review of the content and make their own personal judgements as to its value to them, individually. At the end of the day, facts belong to everybody, any other opinions to us. The distinction is yours to draw...otherwise, the opinions expressed herein are not necessarily those of any employer, not necessarily ours and probably not necessary. Dissenting opinions, discussion or conclusions which may express an adverse position to those expressed herein by specifically cited authors can be addressed in writing by sending an email to the editor at editor@collisionpublishing.com or sending a “regular mail” letter to us at PO Box 3383, Kirkland, WA 98083-3383. By sending correspondence to either our email or snail mail addresses listed in this publication you are agreeing that: (1) we are by definition, “the intended recipient” (2) all information in the email is ours to do with as we see fit and make such financial profit, political mileage, or good joke as it lends itself to and, (3) this overrides any disclaimer or statement of confidentiality that may be included on your original message. The entire physical universe, including this publication and attached data disk, may one day collapse back into an infinitesimally small space.

Should another universe subsequently re-emerge, the existence of this publication and data disk in that universe cannot be guaranteed.

Kinetic Energy Press ......................... Page 35

Submit an Article

WeCare ............................................ Page 95

ARC-CSI Crash ARC-CSI Crash Conference CDs Conference CDs

Cad Zone ......................................... Page 42 CSV Pro 2009 .................................. Page 43 Crash Data Group ........................... Page 58 MapScenes ....................................... Pages 59-62 Northwestern University .................. Page 63 Calc Zone ........................................ Page 83 iWitness ........................................... Page 94 IST .................................................. Page 94 Engineering Dynamics ..................... Page 95

If you would like to submit an article to be published in Collision please email us your article for review or call us toll free 800-280-7940. Email: editor@collisionpublishing.com

Vericom Computers ......................... Page 102

Back Issues

ARC-CSI & CDR User's Summit ... Page 112

If you would like purchase back issues of Collision Magazine, please visit www.collisionpublishing.com/backissues.html or call us toll free 800-280-7940.

Eos Systems (Photomodeler) ............ Page 103

4N6XPRT Systems .......................... Inside Back Visual Statement .............................. Back Cover

Premier Industry Partner Letter From The President

Crash conferences, especially those that include real world crash testing, help fill that need for continuing education. As an added bonus, conference attendees have the opportunity to network with other experts from a variety of disciplines. Having a network of peers with whom you can talk over interesting and complex problems is an invaluable tool. Also invaluable is access to a quality industry publication like Collision. That is why NAPARS recently chose to renew its commitment to include a complimentary subscription to all of our members. If you are interested in receiving Collision through NAPARS, please visit our web site for more details.

As you are reading this issue of Collision, the ink should barely be dry on the 2010 ARC-CSI Crash Conference attendee certificates. Based on the variety of conference topics and the ambitious crash testing planned, the participants should have a wealth of crash data to add to their professional library. I am confident that NAPARS was well represented at the various events, and hope that I was able to meet and speak with as many of our members as possible.

Isn’t it is amazing the difference a year makes? For example, in the span of just a few months we have seen significant changes in the public’s perception of vehicle recorded crash data. In the past, news outlets have reported mainly on the vocal minority which argues that recording crash data is a violation of privacy rights.

But in a sudden reversal, we now are seeing news articles questioning why only the “Big Three” auto manufacturers allow crash data to be publicly available, putting pressure on the foreign car manufacturers to do the same. And now NHSTA finds itself answering questions from Congress about why they do not require manufacturers to record crash data and make it publicly available. That would certainly go beyond the current requirements in 49 CFR Part 563. I have to say it - score one for our side!

Coming this October will be the 2010 Joint Annual Crash Conference in Ocean City, MD. This year’s host will be the Maryland association and they are currently hard at work scheduling the technical presentations and planning the crash testing. Last year, close to 200 people enjoyed both a great crash conference and the warm Maryland sunshine along the Boardwalk. I highly recommend attending this annual crash training event. For more information on the annual conference you’ll find a link on the NAPARS web site.

Chuck Veppert President - NAPARS

Another recent change involves the NAPARS association web site which underwent significant changes recently. I invite you to check out the new look at www.NAPARS.org. Our aim is to make the site more useful, enhance content, and make the site more user friendly for our membership and the public.

Fact is, our industry is all about change. And trying to keep up with changes in methodologies, technology, and all the rest is a daunting but necessary task. Examine most crash expert’s CV and you will usually find a solid foundation of formal education, followed by work experience and up to date continuing education.

WWW.NAPARS.ORG

Industry Partners The International Association of Accident Reconstruction Specialists is one of the oldest associations dedicated to expanding the knowledge and training of accident reconstructionists.

Formed in 1980, we have members from several different countries as well as many different states across the U.S. We have three levels of membership. Our highest level, Fellow, includes a peer review of a reconstruction project. This peer review feature can be very beneficial to a member seeking expert witness qualification in court. One of the criteria a judge can consider when deciding if a person qualifies as an expert is a peer review of his or her work. We offer opportunities for a member to publish work or research in the field of accident reconstruction. This, also, can be very important when qualifying as an expert witness in court proceedings.

Membership in IAARS has other advantages, including a discount (from IAARS) on a subscription to Collision Magazine, member

discounts at our training seminars and others listed on our web page, www.iaars.org.

We have annual training opportunities at different locations across the country. We try to have some sort of actual vehicle testing at each seminar, including full scale vehicle crashes. As a member, you would have access to a vast archive of results from many different and sometimes quite unique tests.

The 30th conference of IAARS will be held in the hometown of one of the founding fathers, Myron Lofgren: Elk River, MN. Meeting location is still to be determined, but they may be held at his home. There is a family-friendly Holiday Inn within about three miles, and there should be rapid transit in place between the nearest airport, Elk River, and the Mall of America by the time the conference begins. The conference will start on Monday, July 19, 2010.

Sincerely, Dan Lofgren President, IAARS www.iaars.org

ASPACI Inc.

The early days saw the number of members vary with the base of the association in Victoria, Australia. ASPACI became ASPACI Incorporated in 1993 in Victoria. Now we boast members from all over mainland Australia, New Zealand., United Kingdom, and the United States, as well as parts of Asia.

ASPACI was formed in 1991 by a group of police and collision reconstructionists who felt there was a need for information sharing between police and associated institutions in the Australia, South East Asia, New Zealand and South Pacific area. Its primary function is to assist in the spreading of knowledge and enhancing expertise in the science. The Association seeks to promote a professional approach to collision investigation and to encourage the highest standard of ethics, integrity and honesty among its members.

Membership to ASPACI is open to all persons engaged in collision investigation and its allied fields. The association members include Engineers, Police Officers, Independent Consultants, Scientists, Insurance Corporations, Manufacturers and Safety personnel. ASPACI is not a Trade Association or Political Lobby group, nor is it a Police organisation.

ASPACI is a non-profit society whose members have joined to share in the challenge of analysing the complicated issues of road collision investigation.

The ARC Network was founded in 1998 and since has grown to be the largest organization for Accident Reconstruction and Traffic Investigation.

The ARC Network is more than just an organization it is a research Internet portal for everything accident reconstruction.

The ARC Network provides research tools, Expert directory, event calendar, industry news feeds, discussioin forum and a Member's Only area that gives members access to various database tools and information.

The ARC Network also acts as a community sharing web site for accident reconstruction. This is the only web site organization that let's you add content to the web site. You can upload news articles, press releases, papers, and even create photo albums and

video albums that relate to accident reconstruction.

Membership starts at just $79.00 per year. However, that is where the value of the ARC Network starts. With your membership you get a free copy of REC-TEC's Drive3 software, $50 discount to the annual ARC-CSI Crash Conference and $50 discount to the CDR User's Summit. Also included is a free copy of Greg Russell's Excel Crush Stiffness spreadsheet program. Sign up as a Police Agency member or Platinum member and you also will receive a complimentary subscription to Collision Magazine!

Visit: www.accidentreconstruction.com Scott Baker President The ARC Network

www.collisionpublishing.com

Collision 7

Back to Table of Contents

"My Turn At the Wheel" L A N I F OTE N

Let me begin by thanking Richard C. Rinker for commenting (in the Fall 2009 issue of Collision) on my “skid” note in the Spring 2009 issue. His comments made me realize that there are a few things that I should have addressed in my note.

Let me begin by stating that the numerical example was intended to be just that: a numerical illustration of how to use the formula. Any semblance to reality was coincidental. Mr. Rinker also mentions that my example failed to take into account rolling resistance. Taking rolling resistance into account when using the formula is trivial, if you make the simplifying assumption that each wheel is in one of two states, rolling or skidding, and the transitions between the two states are instantaneous.

We use

for the mass of the particle,

on which the particle is skidding, and lengths for the wheels by

,

,

for the acceleration of gravity,

for the drag factor of the surface

for the distance the particle skidded. We denote the skid-mark , and

. We assign the indices such that

. We number the wheels such that wheel 1 left a skid mark of length skid mark of length

, wheel 3 left a skid mark of length

Furthermore, we denote the weight on wheel 1 by on wheel 3 by

, and the weight on wheel 4 by

, wheel 2 left a

, and wheel 4 left a skid mark of length , the weight on wheel 2 by

.

, the weight

. (Of course,

.)

Reverting to rolling resistance, the formula is easily obtained by realizing that - from the point of view of mathematics - rolling is “just another skid”, using the formula combining the resulting speed losses:

where I have used

twice, and

for the drag factor for rolling.

Using the conventional approach explained by Mr. Ricker, we split the skid into four pieces: and the braking efficiency is 1. All four wheels left skid marks. The skid mark length for this piece is , or 1. In the formulas that follow, we denote the speed loss from . this partial skid by

2. Three wheels left skid marks. The skid-mark length for this piece is and the braking efficiency is . In the formulas that follow, we denote the speed loss from this partial skid by . and the braking efficiency is 3. Two wheels left skid marks. The skid-mark length for this piece is . In the formulas that follow, we denote the speed loss from this partial skid by .

4. One wheel left skid marks. The skid-mark length for this piece is . In the formulas that follow, we denote the speed loss from this partial skid by

and the braking efficiency is .

We get, using the normal skid formula,

for the four speed losses. Finally, we combine the four speed losses:

Thus, the conventional approach and the “one wheel at a time” approach give identical results; that is one reason the formula

works.

The advantages to the “one wheel at a time” way of thinking are: • There is far less complexity involved. The conventional approach needs to determine four or more unneeded speed losses and then combine these speed losses.

•

It is very easy to deal with gap skids. You just add the skid lengths for each wheel and plug them into the formula . The conventional approach has to calculate a considerable number of speed losses and then combine these. (The exact number of speed losses depends on where the skids and gaps are in relation to each other.)

•

Taking rolling resistance into account is, as shown above, also very easy.

It appears to me that we should be teaching people to use the conceptual model that is simplest and still gives the correct results. Of course, the formula can be taught as a computational shortcut.

A teacher who does not like the “one wheel at a time” approach is free not to mention it, but he owes it to his students to teach

. There is no reason to burden the students with unnecessary computations.

Incidentally, I have yet to hear of a defense attorney who complained that the prosecution underestimated the speed of the vehicle that the defendant was driving.

BY: PETER BERGH

Back to Table of Contents

"GearUp!" is a new feature of Collision Magazine highlighting new and innovative products or devices for the collision research and analysis industry.

In this issue, we spotlight a new compilation of applications for the iPhone or iPod Touch.

Investigators now have a quick and easy way to make common calculations on scene or in the office. Go to Apple's "App Store" for ordering information.

Brought to you by

360Momentum The new "360 Momentum" application for the iPhone and iPod Touch allows the collision investigator to quickly determine vehicle velocities in two vehicle collisions utilizing conservation of linear momentum.

Momentumin-Line The "Momentum In-Line application" for the iPhone and iPod Touch is designed to calculate the speeds of vehicles involved in "in-line" collisions. The program uses conservation of linear momentum calculations in order to determine the velocities.

Airbornes The new "Airbornes" application for the iPhone and iPod Touch calculates the take-off speed of a vehicle involved in an airborne event (vault, fall, or flip). The calculated speed is displayed in both fps and mph in the imperial system and m/s and km/ hr in the metric system. In addition to the takeoff speed, horizontal and vertical velocities are calculated.

Critical Speed The new "Critical Speed" application for the iPhone and iPod Touch allows the investigator to calculate the critical speed of a vehicle that has entered a yaw. The speed calculations are based on the radius based on the chord and middle ordinate measured from one of the vehicle's yaw marks in conjunction with the drag factor and superelevation of the road.

Minimum Speed The "Minimum Speed" application for the iPhone and iPod Touch calculates the minimum speed of a vehicle that is skidding/ slowing based on its skid distance, a braking efficiency, roadway grade and the vehicle's final/impact velocity.

Collision 13

www.collisionpublishing.com

Collision

15

E

Back to Table of Contents

L F A O F EC T TION ET W F C F IRE ON D IRES TION T RAC T

H. J. HERZLICH

HERZLICH CONSULTING, INC.

ROBERT J. SWINT, EDWARD FRITSCH, B. UNSER ATA ASSOCIATES

W

et road traction is an important safety requirement for pneumatic tires. In error, all types of wet traction loss are often described as “hydroplaning” or “aquaplaning.” Hydroplaning is a unique event with a clear definition. Many wet skid events are not hydroplaning but rather the effect of the wet lubrication of the footprint which is influenced by many complex factors. These can include a boundary layer with full road surface contact transitioning into an elastohydrodynamic layer with little contact. When evaluating wet skid events it is important to not automatically assume hydroplaning. One must review facts that may include the possibility of hydrodynamic retardation as the initiator of loss of control.

There is agreement within the tire industry scientific community that road texture, compound hysteresis, speed, footprint load intensity and footprint aspect ratio are important contributing wet traction factors. While there is information describing the importance of the circumferential grooves, there is little information describing the effect or value of certain angular design patterns on wet traction. The void ratio of the tread design is a water evacuation facilitator and an indicator of hydroplane potential. It is universally agreed that increased tread depth of the circumferential grooves is an important contributor to wet skid resistance. www.collisionpublishing.com

Collision 17

the squeegee action of the front tire. Under normal highway steering conditions, it has been shown that the rear tires track the front tires quite accurately.

When water is trapped between the tire tread and the road surface, a hydrodynamic lubrication effect takes place. The fact that the tread is elastic effects the shape of the lubricating film and creates a range of pressures points in the foot print. The thickness and nature of the film is determined by many factors including dynamic fluid viscosity, the road surface micro/macro texture and the ability of the design to rapidly clear the water.

If the tread pattern and the road microtexture is not overloaded with water, there is less tendency to develop the required lifting wedge of water; giving the tread compound better opportunity to contact the road surface. Micro deformation contact with the road microtexture creates the hysteretic traction effect that is unique to rubber.

As the tire rolls with minimum normal slippage, its tread is basically static with regard to the road surface (as is evidenced by the clear tread pattern design left by a rolling tire in snow rather than a smear). When the tire is locked as the vehicle moves, the tread is no longer stationary in relation to the road surface and we have the black smear mark.

Most states require 2/32 removal. California requires 1/32 and South Carolina has no requirement. The DOT requirement for 2/32 molded tread depth indicators is now being questioned as not optimizing the safety potential of today’s radial tires. Work continues to push for the codification of a national 4/32 tread legal depth removal requirement. One major tire manufacturer is already recommending tires be removed when it is worn down to 4/32 remaining.

A study of a broad range of estimated aquaplaning speeds for different types of vehicles concluded that important factors contributing to hydroplane initiation are: “water depth, vehicle speed, vertical load and the width of the tire.

Blyth reviewed of a range of different traction tests on different tire designs and concluded that a significant loss of wet traction capability starts when the 4/32 remaining is reached.

Directional tires are now becoming a more common design. Their groove pattern gives the impression of more aggressive traction capabilities. The distinct angular grooving makes it desirable to control the direction of rotation by having an arrow molded onto the tire sidewall. This is to address certain performance considerations the manufacturer considers important. While having certain aesthetic or claimed technical advantages, the directional requirement creates the problem of making the desired cross axle tire maintenance rotation pattern more difficult by requiring a dismount/ remount to maintain the arrows direction of rotation.

The European Tyre and Rim Technical Organisation (ETRTO) (GRRF-58-20/September, 2005) stated in a memo that:

It is only when the tire is rolling on the road that the tread pattern is able to punch through the lubricating water film as well as functioning as an efficient “pump” expelling water from the footprint.

A locked tire or a tire in a yaw cannot effectively address a wet road condition.

Hydroplaning is a waterborne loss of traction loss due to an overwhelming hydraulic lifting wedge that saturates the foot print. The circumferential tread groove pattern contributes the major portion of water evacuation efficiency. A rear tire gets some benefit from

A study was designed to test reversed rotation with regard to wet braking and wet lane change.

“Mounting a directional tire in the wrong direction is not an inherently unsafe condition. Although the tire will not perform as well as if mounted in the correct direction, the safety performance levels continue to assure adequate control of the vehicle…Three different tire companies performed tests on different brands and designs of tires, where wet road performance was evaluated when one tire was incorrectly mounted. The results were compared to the same tires mounted correctly…in all cases it was shown that the decrease in aquaplaning performance of the tire mounted in the wrong direction was less than the dispersion of aquaplaning performance encountered between different tire brands or different tread patterns within the same brand. In no case was the decrease of aquaplaning seen as a safety concern. The differences are small in relation to the overall spread of aquaplaning performance seen in the marketplace.”

A study was designed to test reversed rotation with regard to wet braking and wet lane change. Besides developing data of broad scope from motion measuring and GPS instrumentation, this study was designed to address a specific issue involving the right front reversed application of a directional tire.

The test vehicle was a 1999 rear wheel drive Chevrolet Camaro described in Table 1 below.

Weight Distribution of 1999 Exemplar Chevrolet Camaro Z28 with 5.7 L V8

The combinations of tires tested at the two test locations are presented in Table 3.

(VIN 2GIFP22G7X2140678)

Table 4 provides additional information on the tires used in the tests conducted at the Houston Community College test track on January 24, 2008. The test surface was wet, but free of puddles.

Left Front

Right Front

960 lbs (empty)

980 lbs (empty)

1040 lbs (with 190 lb driver)

1000 lbs (with 190 lb driver)

Left Rear

Right Rear

740 lbs (empty)

760 lbs (empty)

800 lbs (with 190 lb driver)

800 lbs (with 190 lb driver)

Table 6, 3 pages ahead, presents a comparison of the results from the straight line braking tests conducted at the two test locations.

Table 1 - Exemplar vehicle weights at the 4 wheel positions Laredo Proving Grounds, Ltd. was contracted to make measurements of the surface conditions at three selected test locations - the Houston Community College truck track in Houston, Texas, the wet handling area at the Cooper Tire test track in Pearsall, Texas and a section of Hwy. 69 near Tyler, Texas, which was of interest to the researchers. Friction measurements were made using equipment and procedures as called for on ASTM E274 and using the ASTM E501 pavement measuring tire. The results are outlined in table 2 below.

Test Location

Vehicle Peak Speed Load

Slip @ Peak

Slide Load

mph

%

%

%

Average

40.3

50.6

9.3

31

Maximum

40.6

57.5

19.6

33.7

Minimum

39.9

41.7

3.2

29.1

Standard Deviation

0.2

4.9

4.8

1.5

No. of Samples

10

10

10

10

Highway 69 Average Tyler, Texas Maximum (Next to Center Stripe) Minimum

39.5

104.3

12.8

71.6

40

108.9

15.4

74.8

39.1

97

8.3

67.6

Standard Deviation

0.3

3.1

2.3

2.3

No. of Samples

10

10

10

10

Average

39.8

80.1

7.8

50.7

Maximum

40.6

92.9

15.1

56.3

Minimum

39.2

66.4

4.8

43.8

Standard Deviation

0.5

7.5

3.1

4.6

No. of Samples

10

10

10

10

39.4

82.6

8.9

52.2

39.8

95

11.6

57.1

39.2

71.1

6.1

45

0.2

7.3

1.7

3.8

Houston Community College Track

Highway 69 Tyler, Texas (Left Tire Location in Lane)

Cooper Tire Average Test Track Wet Handling Maximum Area Minimum Pearsall, Texas Standard Deviation No. of Samples

10

10

10

Table 2 - Measured wet surface friction parameters

Straight-line braking tests and lane change maneuvers with the tires shown in Table 5 were conducted at the Cooper Tires facility in Pearsall, Texas on September 10, 2008. Again, the test surface was wet, but free of puddles. Three of the tires in the Cooper set were new tires which had been shaved to replicate a particular state of wear that was of interest to the researchers.

10

In addition to straight line braking tests, maneuverability tests were also conducted on a test course laid out on the wet handling area at the Cooper facility to replicate the dimensions of a divided highway. For these tests, the surface was not flooded, but again only thoroughly wetted with no puddles of standing water. Controlled lane change maneuvers on the wet surface at 55 mph resulted in lateral vehicle accelerations between 0.50g and 0.78g. Losses of control occurred with steering and/or throttle inputs which produced lateral accelerations in the range of 0.95g to 1.06g. The lateral accelerations of the exemplar Camaro fell in these ranges regardless of whether the car was equipped with a properly mounted set of new Michelin tires or with a shaved Cooper tire set with a reversed right front tire that represented a tire configuration of interest to the researchers.

Trajectory plots of the lane change maneuvers which resulted in loss of vehicle control are presented in Figures 1 and 2. The diagrams show 10 Hz GPS data plotted on grids with 12 ft horizontal increments gauging lateral movement and 20 ft vertical increments gauging travel along the length of the test course. Each lane change maneuver was initiated at the “zero” point at the bottom of these figures. Overlaid on the grid is a representation of a 5-lane highway consisting of 2 forward lanes and 2 oncoming traffic lanes separated by a median lane. Figure 1 shows those trajectories in which the final vehicle rest position was to the left of the centerline of the “target” lane, i.e. that lane in which a successful lane change maneuver should have ended. Figure 2 shows those trajectories with the vehicle final rest position right of the target lane centerline.

Figure 1 - Trajectories to the left Figure 2 - Trajectories to the right An analysis of the trajectories shown in the figures can be summarized as follows. Final vehicle rest position was to the left of the target lane centerline in 10 of 17 (or 59%) of the losses of control.

Description of Tire Set

1

Used Falken 21EXE512 - Properly mounted on all 4 wheels

Test Location; Test Number

Tread Appearance

Houston Community College; A

Used Falken Tread 2

Used Falken 21EXE512 - Reversed on all 4 wheels

Houston Community College; G

3

Used Falken 21EXE512 - Properly mounted on LR,RR,LF New Falken 21EXE512 - Reversed on RF

Houston Community College; B

New Falken Tread

4

Used Falken 21EXE512 - Properly mounted on LR,RR,LF New B.F. Goodrich Sport - Reversed on RF

Houston Community College; C

B.F. Goodrich Sport Tread

5

Used Falken 21EXE512 - Properly mounted on LR,RR,LF New B.F. Goodrich G-Force T/A - Reversed on RF

Houston Community College; D

B.F. Goodrich G-Force T/A

6

Used Falken 21EXE512 - Properly mounted on LR,RR,LF New Firestone Firehawk Oval - Reversed on RF

Houston Community College; E

Firestone Firehawk Tread

7

Used Falken 21EXE512 - Properly mounted on LR,RR,LF New Michelin Pilot - Reversed on RF

Houston Community College; F

Michelin Pilot Tread 8

New Michelin Pilot - Properly mounted on all 4 wheels

Houston Community College; H Pearsall, Texas; 1

9

New Michelin Pilot - Reversed on all 4 wheels

Houston Community College; M & O Pearsall Texas; 6

New Michelin Pilot - Properly mounted on LR, 10 RR, LF New Michelin Pilot - Reversed on RF

Houston Community College; I Pearsall, Texas; 2

New Michelin Pilot - Properly mounted on LR, 11 RR, LF New B.F. Goodrich Sport - Reversed on RF

Houston Community College; J Pearsall, Texas; 3

New Michelin Pilot - Properly mounted on LR, LF 12 RR, New B.F. Goodrich G-Force T/A - Reversed on RF

Houston Community College; K Pearsall, Texas; 4

New Michelin Pilot - Properly mounted on LR, 13 RR, LF New Firestone Firehawk Oval - Reversed on RF

Houston Community College; L Pearsall, Texas; 5

Shaved Cooper Futura - Properly mounted on 14 LR,RR,LF New Cooper Futura - Properly mounted on RF

Pearsall, Texas; 7

Shaved Cooper Futura Tread

Shaved Cooper Futura - Properly mounted on 15 LR,RR,LF New Cooper Futura - Reversed on RF

Pearsall, Texas; 11

New Cooper Futura Tread 16 Shaved Cooper Futurat - Properly mounted on LR, RR, LF New B.F. Goodrich Sport - Reversed on RF

Pearsall, Texas; 8

17 Shaved Cooper Futura - Properly mounted on LR, RR, LF New B.F. Goodrich G-Force T/A - Reversed on RF

Pearsall, Texas; 9

18 Shaved Cooper Futura - Properly mounted on LR, RR, LF New Firestone Firehawk Oval - Reversed on RF

Pearsall, Texas; 10

19 New Cooper Futura - Reversed on LF Shaved Cooper Futura - Reversed on LR, RR, Pearsall, Texas; 12 RF Table 3 - Tire Set Matrix for Braking and Maneuvering Tests

TEST A – FALKEN 21EXE5121 (All tires properly mounted)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

V4PJXMTR1605

7.0-5.0-7.0

82

Rear Right2

V4PJXMTR1605

7.0-5.0-7.0

82

Front Left

V4PJH12R3404

7.0-5.0-7.0

83

Rear Left2

V4PJXMTR1605

7.0-5.0-7.0

83

TEST B – NEW FALKEN 21EXE512 (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

V4PJXMTR5006

10.0-10.0-10.0

78

TEST C – B.F. GOODRICH SPORT (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

BEX1FN114307

9.75-9.75-9.75

82

TEST D – Position B.F. GOODRICH G-FORCE T/A (Reversed on Front Right) Front Right

DOT No.

Tread Depth, 32nds

Durometer

BAX1EL113605

10.0-9.75-10.0

86

TEST E – FIRESTONE FIREHAWK OVAL (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

EJPJJADA805

10.0-10.25-10.0

90

TEST F – MICHELIN PILOT (Reversed on FrontRight)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

4M3WC84X3607

9.75-9.75-9.75

81

TEST G – FALKEN 21EXE51 (All Test A tires reversed3)

Position

DOT No.

Tread Depth, 32nds

Durometer

-

-

-

-

TEST H – MICHELIN PILOTS4 (All tires properly mounted)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

4M3WC84X3607

9.75-9.75-9.75

81

Rear Right5

4M3WC84X3607

9.75-9.75-9.75

81

Front Left5

4M3WC84X3407

9.75-9.75-9.75

81

Rear Left5

4M3WC84XS106

9.75-9.75-9.75

81

TEST I – FALKEN 21EXE512 (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

V4PJXMTR5006

10.0-10.0-10.0

78

TEST J – B.F. GOODRICH SPORT (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

BEX1FN114307

9.75-9.75-9.75

82

TEST K – Position B.F. GOODRICH G-FORCE T/A (Reversed on Front Right) Front Right

DOT No.

Tread Depth, 32nds

Durometer

BAX1EL113605

10.0-9.75-10.0

86

TEST L – FIRESTONE FIREHAWK OVAL (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

EJPJJADA805

10.0-10.25-10.0

90

TEST M – MICHELIN PILOTS (All Test H tires reversed3)

Position

DOT No.

Tread Depth, 32nds

Durometer

-

-

-

-

TEST O6 – MICHELIN PILOTS (Same tires as Test M)

Position

DOT No.

Tread Depth, 32nds

Durometer

-

-

-

-

2

Table 4 – Straight line braking tests at Houston Community College truck track Notes On Houston Community College Tests: 1. The used set of Falken tires purchased with the exemplar vehicle were used as the first set of exemplar tires.

2. Falken tires on rear right, front left and front right remained in place for Tests A through F. 3. Front right swapped with front left; rear right swapped with rear left.

4. A set of new Michelin Pilots was chosen as the exemplar "control" set of tires to serve as a basis for comparing the performance of other tires.

5. Michelin tires on rear right, front left and front right remained in place for Tests H through L. 6. Test O was the same as Test M, except driver took hands off steering wheel during braking to emphasize stability. There was no Test N.

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

4M3WC84X3607

9.0-9.0-9.0

81

Rear Right2

4M3WC84X3607

9.0-9.0-9.0

81

Front Left2

4M3WC84X3407

9.0-9.0-9.0

81

Rear Left2

4M3WC84XS106

9.0-9.0-9.0

81

TEST 2 – MICHELIN PILOT (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

4M3WC84X3607

9.0-9.0-9.0

81

TEST 3 – B.F. GOODRICH SPORT (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

BEX1FN114307

9.25-8.25-9.25

82

TEST 4 – B.F. GOODRICH G-FORCE T/A (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

BAX1EL113605

9.75-9.75-9.75

86

TEST 5 – FIRESTONE FIREHAWK OVAL (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

EJPJJADA805

10.0-10.0-10.0

86

TEST 6 – MICHELIN PILOTS (All Test 1 tires reversed3)

Position

DOT No.

Tread Depth, 32nds

Durometer

-

-

-

-

TEST 7 – COOPER FUTURAS (All tires properly mounted)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

UPW9XBW3603N03R

11.0-5.0-11.0

72

Rear Right4

UPW9XBW0703

7.0-4.0-7.0

80

Front Left4

UPW9XBW2803L12L

6.0-4.0-6.0

78

Rear Left4

UPW9XBW1602N09R

7.0-4.0-7.0

74

TEST 8 – B.F. GOODRICH SPORT (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

BEX1FN114307

9.25-8.25-9.25

82

TEST 9 – B.F. GOODRICH G-FORCE T/A (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

BAX1EL113605

9.75-9.75-9.75

86

TEST 10 – FIRESTONE FIREHAWK OVAL (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

EJPJJADA805

10.0-10.0-10.0

90

TEST 11 – NEW COOPER FUTURA (Reversed on Front Right)

Position

DOT No.

Tread Depth, 32nds

Durometer

Front Right

UPW9XB3303C19R

10.0-4.5-10.0

79

TEST 12 – COOPER FUTURAS (All Test 7 tires reversed3)

Position

DOT No.

Tread Depth, 32nds

Durometer

-

-

-

-

TEST 1 – MICHELIN PILOTS1 (All tires properly mounted)

Table 5 - Braking and maneuvering tests at Cooper Facility in Pearsall, Texas Notes On Cooper Tire Track Tests: 1. Same Michelin tire set as used in Houston Community College tests.

2. Michelin tires on rear right, front left and front right remained in place for Tests 1 through 5.

3. Front right swapped with front left; rear right swapped with rear left.

4. Cooper tires on rear right, front left and front right were new tires shaved to replicate the worn tires on the subject vehicle at the time of the accident. They remained in place for Tests 7 through 11.

Summary of Straight Line Stopping Tests HCC

Decel,

Decel,

Pearsall

Decel,

Decel,

Test #

fps2

g

Test #

fps2

g

H1

19.773

0.61

H2

20.993

0.65 1

29.588

0.92

3

29.477

0.92

4

29.253

0.91

5

29.421

0.91

6

28.176

0.88

2

29.204

0.91

7A

25.355

0.79

7B

26.474

0.82

Shaved Cooper Futuras mounted properly on 3 wheels; new B.F. Goodrich Sport reversed on R.F.

8

25.357

0.79

Shaved Cooper Futuras mounted properly on 3 wheels; new B.F. Goodrich G Force T/A reversed on R.F.

9

27.400

0.85

Shaved Cooper Futuras mounted properly on 3 wheels; new Firestone Firehawk Oval reversed on R.F.

10

28.001

0.87

Shaved Cooper Futuras mounted properly on 3 wheels; new Futura reversed on R.F.

11

27.284

0.85

12

25.711

0.80

Table 6 - Straight line braking results Michelin Pilots properly mounted on all wheels

0.63 Michelin Pilots on 3 wheels; new B.F. Goodrich Sport reversed on R.F.

J1

20.414

0.63

J2

20.885

0.65 0.64

Michelin Pilots on 3 wheels; new B.F. Goodrich G Force T/A reversed on R.F.

K1

21.609

0.67

K2

21.021

0.65 0.66

Michelin Pilots on 3 wheels; new Firestone Firehawk Oval reversed on R.F.

L1

21.852

0.68

L2

20.892

0.65 0.66

Michelin Pilots reversed on all wheels

Michelin Pilots reversed on all wheels; driver stopped with hands off steering wheel

M1

21.881

0.68

M2

21.359

0.66

O1

22.197

0.69

O2

22.003

0.68 0.68

Michelin Pilots mounted properly on 3 wheels; Michelin Pilot reversed on R.F Shaved Cooper Futuras mounted properly on 3 wheels; new Futura mounted properly on R.F.

Shaved Cooper Futuras reversed on 3 wheels; new Futura reversed on L.F.

Used Falken 21EXE512 on all wheels

A1

19.026

0.59

A2

19.280

0.60 0.59

Used Falken 21EXE512 on 3 wheels; new Falken 21EXE512 reversed on R.F.

B1

19.697

0.61

B2

19.505

0.61 0.61

Used Falken 21EXE512 on 3 wheels; new B.F. Goodrich Sport reversed on R.F.

C1

19.666

0.61

C2

19.113

0.59 0.60

Used Falken 21EXE512 on 3 wheels; new B.F. Goodrich G Force T/A reversed on R.F.

D1

19.709

0.61

D2

19.556

0.61 0.61

Used Falken 21EXE512 on 3 wheels; new Firestone Firehawk Oval reversed on R.F.

E1

18.978

0.59

E2

19.282

0.60 0.59

Used Falken 21EXE512 on 3 wheels; new Milchelin Pilot reversed on R.F.

F1

19.598

0.61

F2

19.844

0.62 0.61

Used Falken 21EXE512 reversed on all wheels

G1

18.912

0.59

G2

18.796

0.58 0.59

New Michelin Pilots on 3 wheels; new Falken 21EXE512 reversed on R.F.

I1

20.740

0.64

I2

20.730

0.64 0.64

Final vehicle rest position was to the right of the target lane centerline in the remaining 41%. Vehicle rotation was counterclockwise in 13 of 17 (or 76%) of the losses of control. Vehicle rotation was clockwise in the remaining 24%. In the four losses of control that resulted in clockwise vehicle rotations (shown in red in Figure 2), the final vehicle rest position was right of the target lane centerline.

The trajectories to the left resulted from an overcompensating steering input to the left which was applied after the vehicle moved right following completion of the initial lane change. In those trajectories to the left, the vehicle turned 180 degrees from its original direction of travel, i.e. the vehicle swapped ends, at an average distance of approximately 356 feet from the origin of the initial lane change to the left. The average speed at the point where the vehicle swapped ends was 27 mph.

C B

onclusion The testing described in this report showed that mounting one or more directional tires opposite the intended direction of rotation did not adversely affect wet braking or wet handling of the Camaro. This data supports the ERTRO position that mounting and using a directional tire in the wrong direction is not unsafe. ibliography: Blythe, Day; Single Vehicle Wet Road Loss of Control; Effects of Tire Tread depth and Placement. SAE 2002-010553

Metz, Kinney, Herling; Realistic Rear Axle Hydroplaning During Forward Motion, SAE 2006-01-1560 Hayes, Ivey, Gallaway; Hydroplaning, Hydrodynamic Drag, and Vehicle Stability, Frictional Interaction of Tire and Pavement, ASTM STP 793 Hight, Wheeler, Reust, Birch; The Effects of Right Side Water Drag on Vehicle Dynamics and Accident Causation, ASTM 9001105 Browne, Whicker; Design of Tire Tread Elements for Optimum Thin Film Wet Traction, SAE 770278 Brown, Whicker, Rohde; The Significance of Tread Element Flexibility to Thin Film Wet Traction, Tire Science and Technology, 1975s Transportation Research Record 621, Veith, Tire Wet Traction; - Using the “Criticality” Concept, American Chemical Society , Montreal, CA 1996 Benson, Henry, Adams; A Tread-Deflection Measurement System Utilized in Tire Hydroplaning Studies, SAE 800243 Lee; A Computational-Efficient Method to Analyze Viscous Hydroplaning of Pneumatic Tires, SAE 971106

Veith; Tire Traction vs Tread Compound Properties-How Pavement Texture and Test Conditions Influence the Relationship, American Chemical Society, October 1995 Albert; Tires and Hydroplaning, SAE 680140 Navin; Hydroplaning and Accident Reconstruction, SAE 950138 Horne, Joyner; Pneumatic Tire Hydroplaning and Some Effects on Vehicle Performance, SAE 970C For a DVD showing video of the actual tests, contact Robert Swint at ata@ataassociates.com This article was originally published online in the July 27, 2009 Rubber News Technical Notebook and reprinted in Collision with permission of ATA Associates.

Back to Table of Contents

wet or frozen acm access considerations Sean Haight Collision Safety Institute

28 Collision

www.collisionpublishing.com

I

ntroduction Evaluating Airbag Control Module survivability has been a topic of relatively limited research and testing although there have been several narrowly focused projects addressing durability and survivability as seen later in this narrative. Since every type of environmental scenario simply cannot be tested, research must be focused and ongoing. This report discusses the survivability of multiple Airbag Control Modules in situations where they are powered up while in different forms/states of liquids.

"Group: Obviously the preferred method is to conduct the download with the ACM still in the vehicle.

However, what call do you make when the ACM is obviously wet? Do you refrain from putting any power to the unit, remove and dry it, and then do a bench download (in this case talking about a GM SDM). (Video tape the removal, ect.) Or do you take a chance that you might fry it, put power to it while still in the vehicle, and then remove only if unsuccessful?"

The Bosch preferred Crash Data Retrieval Certification Course material, which follows the CDR software Help file’s best practice recommendation, indicates that the first, best method for any routine CDR imaging is to connect through the Diagnostic Link Connector or DLC. This method utilizes the internal wiring and communication in the vehicle and provides a quick and easy method to retrieving crash data. However, the question remains: what are the consequences of such an attempt to imagine if the module is obviously wet, having been previously soaked, submerged, or frozen in a liquid?

Some have suggested that attempting with a DLC connection could destroy the electronic components inside of the module and potentially render the data useless.

This scenario was discussed on the Yahoo! CDR User’s Group in this post and the ensuing thread:

This forum post suggests a possible flaw in routine operation. One might consider what would happen to a mobile phone under the same environmental conditions.

Imagine yourself accidently falling into a pool or pond with your phone still in your pocket. In most cases, these type of mistakes ruin your favorite personal electronics and they are often un-repairable. When electronics are placed in non-distilled water, for example, the ionic elements in the water will short out the connections on the printed circuit boards. This will cause damage to the internal components of the device. How does this analogy compare to the Airbag Control Module?

www.collisionpublishing.com

Collision 29

P

rior Research Previously published research on this subject, as it relates to fluids, can be found in the article "EDR Durability and 49CFR63 Survivability Requirements" by Wade Bartlett.

This research was published in Collision Magazine, Volume 2, Issue 1. Bartlett performed several submersion tests including salt and fresh water. In addition, tests were performed on modules in frozen conditions. It was concluded that "EDRs (sic) will [not] have any difficulty in meeting the survivability requirements newly outlined in 49CFR563." In the Federal Regulation 49CFR563.10, we find the minimum survivability requirements for vehicles, however it does not describe scenarios involving water (whether liquid or solid). Bartlett also concluded that “EDRs (sic) have commonly been seen to survive crashes much more severe in nature than anything specified in the FMVSS regulations, including fires, physical damage, and submersion.” While this research answered some of the questions involving Airbag Control Modules, it still left uncertainty regarding powering up these modules in a submerged or frozen state. Bartlett’s research addressed a module that had been wet and was, when the attempt to image data was made, had been dried. The underlying separate question addressed here was: “if the module is still wet (or frozen) when there’s an attempt to image would something related to the module being wet effect the data?”

T

est Procedure To further explore the ramifications of powering up an ACM while in a liquid, a series of tests were conducted with a group of airbag control modules (ACMs). The “Scientific Method” suggests that each experimental procedure be based on the principles of gathering observable, empirical, and measurable evidence and information. In addition, before the test is performed a hypothesis must be made to project expected or anticipated results. One possible outcome from submerging an ACM in a liquid like water would be that there is no communication with the module or, in other words, the Bosch hardware/software simply could not recover the information stored in the module. Another possible outcome is that the data was recoverable even while the module is submerged or frozen. Since the Bosch CDR software protocol includes multiple (3) passes or checks of the incoming data, it is also possible that one of the outcomes would result in a match error. This would mean that the data was collected for one pass but it failed for another. One other potential outcome is that that the data stored inside of the module, or the module itself, could be erased or destroyed entirely (“fried”).

Five Airbag Control Modules were selected as the test specimens.

Four of them were Delphi SDM-RSDD modules from General Motors vehicles. These modules were selected because they are the least watertight of the modules available and are easiest to open and expose the internal electronics directly to a fluid. Four of the same modules were selected to have a larger sample of the same modules under different scenarios. A fifth module, a Takata RCM from a Ford Crown Victoria was also used to give some module variety to the experiment (that module was opened to similarly expose the internal electronic components). The modules were labeled 1 through 5 (see figure 1).

Prior to any survivability test, every module was downloaded to provide a baseline data file. None of the modules had previously been exposed to fluids as they would be in this test series. All of the modules were downloaded for baseline data without any connection issues. Table 1 shows the event names that existed before any fluid based tests were performed. After successful baseline downloads of all 5 modules, they were put to the test in various liquid related scenarios.

Module 1

Deployment

Module 2

Deployment

Module 3

Deployment

Module 4

Deployment

Module 5

Deployment

Non-Deployment Non-Deployment (only stores one event)

Table 1: Summary of events stored in each test module prior to experiment.

T

est 1 The first experimental scenario examined how an ACM would download in a solid, frozen state. To set this up, the metal cover of module number 1 was removed and the module was placed in a container with household, unfiltered tap water. It was then placed in a freezer for more than 24 hours (see figures 2 and 3). Special consideration was given to the placement of the module in the water before freezing such that the water level of the container submerged the entire module up to the main pin connections (see figure 4).

Figure 1: Test modules 1-5

Figure 2: Placing Module 1 in a container to be frozen Figure 3: Frozen Airbag Control Module The frozen module, or “SDMcicle,” was removed from its container as a block of ice and immediately connected to the Bosch CDR interface using the appropriate direct-to-module cable. The VIN for that module was entered into the CDR software and the download process was initiated. While completely frozen, the module was successfully downloaded without any errors. In addition, the CDR software reported that both the Deployment and Non-Deployment data were unchanged from the baseline download.

Figure 4: Close-up of pin connections on Module 1

After just minutes of sitting at room temperature, the ice had started to melt back into its liquid form. Once the ice had melted to the point where there was standing ice but the module was still wet, a downloaded was again attempted. This time; however, the CDR software was not able to connect to the module. The error dialog box read: "Collect data failed! No Communications with module. Please check DLC cable or cable to module" (see figure 5). The module was disconnected and the remaining ice was removed. The module was then placed outdoors in the sun for about 30 minutes. After the visible residual water had evaporated from the components, the module was connected back to the CDR interface and computer. After www.collisionpublishing.com

Collision

31

that drying was complete, the module was successfully downloaded.

The CDR software reported that both the Deployment and Non-Deployment data were un-changed from the baseline download.

T

est 2 The second test was designed to simulate liquid submersion after the download has stared. Module number 2 was connected to the Bosch CDR interface by the direct-to-module cable and placed on a table (see figure 6). The VIN number for the module was entered in the software and the download was initiated.

After the first pass was complete, and the second pass had just started, the module was carefully placed into a bowl of generic tap water (see figure 7) making sure the direct-to-module cable remained in place.

The rest of the download process was concluded with the module still in the water bowl.

Figure 5: Collect Data error message

The CDR software did not successfully image the module and the following error was reported: "Collect data FAILED! Software ID: 0073. Read one: Passed. Read two: Passed. Read three: Passed. Match: FAILED. Check power to interface and the communication cables.

Turn ignition off for five seconds, then turn ignition on and try again.

Make sure vehicle ignition switch is on and engine not running.

Check vehicle battery voltage. Possible incorrect system selected." (see figure 8).

Like module 1, this module was then placed in direct sunlight for about 30 minutes. In addition, a can of compressed air was used to remove any remaining water droplets. The module was again connected to the CDR interface and computer. After this drying process, another download was attempted and ran to completion with the CDR software reporting that the Deployment data was un-changed from the baseline download.

Figure 6: Direct-to-module cable connection

Test 3 The third test was designed to simulate an Airbag Control Module that is in still, fresh water; completely submerged. Module number 3 was placed in the same bowl of fresh water as test number 2. It was connected to the CDR interface module and computer (see figure 9). Like the previous tests, the CDR software was started and began downloading the data from the module. The CDR software was not able to connect to the module. The error message read: "Collect data FAILED! No Communications with module. Please check DLC cable or cable to module" (see figure 5).

The module was dried using the previously described combination of the exposure to the sun and air can drying techniques. After the remaining water was removed, the module was downloaded without any errors and the two events that were previously observed in that module had not been changed from the baseline download.

Figure 7: Module 2 placed in a container with tap water.

T

est 4 In addition to fresh water, an ACM was also placed in salt water. For this experiment, a sample of sea water from San Diego bay was collected and placed in a similar bowl. The salt water was captured near the end of the bay nearest the ocean where chemical and metal residuals would be minimal. There were the typical biological particulates observed the salt water such as bits of kelp and silt (and one live ghost shrimp). Module number 3 was connected to the CDR interface module and then placed into the bowl of salt water (see figure 10). After the module settled in the water, it was downloaded using the same procedure as observed in the previous tests.

Like test number 3, the CDR software could not make a connection with the module and it provided the error: "Collect data FAILED! No Communications with module. Please check DLC cable or cable to module" (see figure 5).

The module was then dried as was done in the previous tests. After the remaining water was removed, the module was downloaded without any errors and the two events that were stored had not been changed from the baseline download.

Figure 8: Match error message

Figure 9: Connection method while the module was submerged

T

est 5 Considering that these modules are installed in vehicles, that may contain several types of automotive fluids and hazardous materials, one test was attempted with a “typical” vehicle fluid. Test number 5 was designed to simulate a severe crash were fluids from the engine compartment may have leaked into the passenger compartment and flooded the Airbag Control Module. For this experiment, engine coolant was used as the test liquid based on the idea that it would be most readily available in quantity in a car after a crash.

Module number 4 was connected to the CDR interface and the computer, placed in the coolant, and download attempted (see fig-

ure 11). The CDR software could not collect the data from the module and provided the same error message as tests 3 and 4 (see figure 5). The module was taken out of the coolant and rinsed in tap water. It was dried and downloaded again with no errors. Like the previous tests, the collected data was identical to the baseline download.

T

est 6 The last test was a interesting hypothetical scenario. It was designed to simulate the driver with the over-super-sized ultra-44 ounce cup of cola getting in a collision coming from the local convenience store. To create this scenario, a 2 liter bottle of generic cola was poured into the same bowl as the previ-

Figure 10: ACM submerged in salt water (left) Figure 11: ACM submerged in engine coolant (right)

www.collisionpublishing.com

Collision

33

ous tests (see figure 12). Cola was selected has having a reputation of being highly corrosive. This was another reason for this particular test. Module number 5 was connected using the appropriate direct-to-module cable and a download was attempted.

This test provided the most visually interesting results of the entire experiment. Once the power was connected to the CDR interface module, the cola started to fizz and bubble aggressively (see figure 13). This reaction occurred very rapidly after the power was connected. Similar to the previous submersion tests, the ACM was not successfully downloaded and the connection error previously returned was observed. The module was taken out of the cola and rinsed in regular tap water. It was dried and downloaded again with no errors. Like all the previous tests, the collected data was identical to the baseline download.

A

nalysis Test 1 indicates that completely frozen water encasing a module does not have an effect the data collection process, nor does it damage the module in any way. This is most likely due to the fact that completely frozen ice is not a conductor. This means that ice does not allow the electrons to flow across it like metal or other minerals would. Once the ice starts to melt however, the electrons move freely through the non-distilled water left behind. Like tests 3, 4, 5, and 6, the conductive liquids that the modules were placed in cause shorts in the connections of the different internal components. This short caused communication problems and the CDR system was not able to retrieve the data from the module memory.

More importantly, none of the modules tested in these liquids were permanently damaged. After they were dried, the short circuit conditions were removed, and the module worked perfectly. None of them were "fried" from the electrical currents applied while wet and none of the data was lost. In addition, exposure to corrosive liquids like salt water and cola caused no short term damage on ACMs while they are powered up. Lastly, hazardous materials like engine coolant also have no short term effect on an ACM when it is being imaged.

Figure 12: Placing Module 5 in a container filled with cola

C

onclusions The purpose of this experiment was to provide a reasonable set of data and a baseline protocol for downloading an Airbag Control Module while it is obviously submerged or may have been submerged in liquid or frozen. Based on these results, attempting to download a seemingly submerged or frozen module through the Diagnostic Link Connector is still the first, best method for collecting crash data and even if the module has been wet, the most likely result will be a communications failure not a loss or “corruption” of the stored data. While this experiment was conducted on a small sample of modules in a small sample of liquids and there are many different variations of ACM types and many different types/solutions of liquids which may reach a module in a vehicle after a crash, the selection here seems to be demonstrably representative of the potential for the module-fluid exposure combination likely to be encountered in the field.

Figure 13: Result of powering-up a Airbag Control Module in cola

Back to Table of Contents

Back to Table of Contents

Insurance Applications for Crash Data Retrieval, Legal Considerations Commerce Insurance Co. Michael L. Merolli Smith & Brink PC David O. Brink, Esq. Smith & Brink PC Patrick M. Conran, Esq., Jasmine Garcia-Vieux, Esq. Smith & Brink PC

T

he aviation industry has been utilizing Event Data Recorder ("EDR") technologies, commonly known as "black boxes" in airlines since the late 1950s. Thereafter, General Motors saw the advantages of this technology and began integrating basic EDR capability into some of its vehicles as early as 1994. These early EDRs simply recorded airbag performance results, braking distance and speed at impact. Now, just a few years later, EDRs are present in almost all mass produced

36 Collision

vehicles. However, to make matters more complex, the technology underlying today’s EDRs is becoming more sophisticated with each model year.

C

rash Data Retrieval Laws Federal Regulations In 2004 the National Highway Traffic Safety Administration (hereinafter "NHTSA") began drafting guidelines regulating EDRs1. These proposals set forth minimum recording standards for EDRs

www.collisionpublishing.com

and required manufacturers to include notice in owner’s manuals informing purchasers about the existence of such equipment.

These proposed EDR regulations were later codified in August of 2006 within the Code of Federal Regulations. See 49 CFR 563. This Federal law requires that any vehicle manufactured after September 1, 2010 -- which is equipped with an EDR as defined in the regulation – must capture specific minimum information. This required data includes, by way of illustration rather than limitation, delta-V, indicated vehicle speed, engine throttle, safety belt status and airbag deployment. The regulation also include a second table of "optional" data which must be captured in a particular format, if the vehicle is equipped.

S

tate Statutes Individual states have also enacted laws addressing black box technology in automobiles, including Arkansas, California, Colorado, Connecticut, Maine, Nevada, New Hampshire, New York, North Dakota, Oregon, Texas and Virginia2. All other states have not passed a EDR law except for Washington, which has approved an Act slated to go into effect in July 20103. The Legislatures for the twelve states that enacted EDR statutes incorporated language giving "ownership" of any information stored on a EDR to the vehicle's owner. Owners are defined in different ways in each statute. Generally, however, the statutes identify the owner as the person or entity who has legal title to the vehicle, one who is a lessee of more than three months or one who is entitled to possession of the vehicle under a security agreement.

While these laws generally establish that data recorded on a EDR is the property of the owner of the vehicle, there are enumerated exceptions.

One such exception common to all twelve statutes states is that EDR information can be downloaded if the owner (or the owner’s legal representative) consents to the retrieval of the in-

formation. Some states (e.g., New York, Maine and Connecticut) give the "right to consent" to the owner of the vehicle at the time the data is accessed or retrieved4. Other states (New Hampshire, Oregon, North Dakota, Arkansas and Washington) grant that "right to consent" to the owner of the vehicle at the time of the accident or, when the data is created or recorded5. The remaining states (Colorado, California, Texas, Virginia, and Nevada) make no distinctions and simply give the right to consent to the "registered" or "titled" owner6. None specify any protection for the driver of the vehicle at the time of a crash All twelve state statutes (plus Washington) allow for the retrieval of the available EDR information upon an order of a court of competent jurisdiction. Some distinctions include: • Connecticut allows data to be retrieved pursuant to a search warrant or "a legally proper discovery request or order in a civil action."7 • In Maine, the applicable statute simply holds that EDR information can be retrieved as part of "routine civil or criminal discovery."8 • Oregon’s statute sets forth a specific petition process in order to obtain a court order.9 Some states have even made specific reference to an insured’s obligation to cooperate. For example: • The Maine statute states that nothing in the statute affects "an insured’s duty to cooperate as provided in an applicable insurance contract or agreement."10 Therefore, at least in Maine, an insurer has a basis to argue that an insured’s duty to cooperate includes giving consent to retrieve EDR data.

• The Arkansas statute has a similar "cooperation" pro-vision, but goes on to

www.collisionpublishing.com

Collision 37

state that, "the ownership of the data does not pass to a lienholder or to an insurer because the lienholder or insurer succeeds in owner-ship of the vehicle as a result of the accident" and "the lienholder or insurer [cannot] make the owner’s consent … conditioned upon the payment or settlement of an obligation or claim." "[H]owever, the insured is required to comply with all policy provisions, including any provision that requires the insured to cooperate with the insurer."11 • Virginia may have the most interesting provision in its EDR statute as it includes language holding that "[t]he failure of an insurer to obtain access to the recorded data shall not create, nor shall it be construed to create, an independent or private cause of action in favor of any person." 12 The issue now surfaces; what happens if a party retrieves or utilizes EDR data without the proper consent or pursuant to another valid exception? One state (Colorado) considers such a violation, a misdemeanor punishable by imprisonment up to 18 months, a fine up to $5,000 or both.13 Washington’s Legislature has determined that such a disclosure would be considered a misdemeanor.14 Interestingly, California’s statute had originally held that improper access of CDR data could be considered a criminal "infraction" but that provision has since been removed from the regulation.

New Hampshire and Washington have decreed that the improper retrieval of EDR data may constitute an unfair or deceptive act or practice.15 The remaining states provide no express remedy for a violation of their respective statutes.

Notwithstanding the foregoing, general theft and privacy laws could conceivably apply if a representative of an insurance company retrieved data without the consent of the vehicle owner. This would be especially true in those jurisdictions where the ownership of EDR data is granted by statute to the titled vehicle owner.

T

he Insurance Policy As an example, the Standard Massachusetts Automobile Insurance Policy (Seventh Edition) contains the following language regarding the insured’s duty to cooperate in the investigation of a claim: "After an accident or loss, you or anyone else covered under this policy must cooperate with us in the investigation, settlement and defense of any claim or lawsuit. We must be sent copies of all legal documents in connection with the accident or loss. *** Failure to cooperate with us may result in the denial of the claim."

Prior to 1990, under Massachusetts law, a breach of the duty to cooperate on the part of an insured must have been "substantial and material" before an insurer was permitted to disclaim liability.16 However, since then, a showing of prejudice on the part of the insurer is required except in certain limited situations.17 A "vast majority of jurisdictions which have considered the issue have decided that actual prejudice to an insurer's interests due to lack of an insured's cooperation must be demonstrated before a denial of coverage will be permitted."18 Thus, it would appear that if an insurer is seeking to disclaim coverage due to an insured’s refusal to allow an insurer to retrieve EDR data, it must be able to demonstrate actual prejudice.

As the Massachusetts Supreme Judicial Court wrote, the courts in most other states have reached similar conclusions. For example:

"" Since the EDR data is generally considered the property of the vehicle owner, an insurer should obtain the named insured’s permission

Since the EDR data is the property of the vehicle owner, an insurer should obtain the named insured’s permission when it seeks to access and retain this information. This consent is not necessary if the title has passed to the insurer after a total loss (except in Arkansas or Oregon -- where "accident related" EDR data remains the property of the prior owner even after title has passed to an insurer or a lienholder in a repossession situation).

S

tates Without Statutes Given that a majority of states do not have statutes, it is important that insurers look at the applicable insurance policy and decisional law when analyzing their rights and obligations regarding the handling of EDR data.

38 Collision

• New Jersey where an insurer must demonstrate "appreciable prejudice" in order to disclaim coverage based on an insured’s breach of the cooperation clause;19 • Illinois where the Courts have concluded that the applicable test in that state is whether the insurer is able to articulate and prove that the lack of cooperation by the insured "substantially prejudiced" the insurer;20 • Connecticut where an insurer must establish that the lack of cooperation by the insured "adversely affected its interest in some substantial and material way";21 • California which has held that "an insurer, in order to establish it was prejudiced by the failure of the insured to cooperate in his defense, must establish at the very least that if the cooperation clause had not been breached there was a substantial likelihood the trier of fact would have found in the insured's favor".22

A

dmissibility of Event Data Recorder Retrieved Information In general, "expert opinion based on a scientific technique is inadmissible unless the technique is 'generally accepted' as reliable in the relevant scientific community."23 An "expert opinion based on a methodology that diverges significantly from the procedures accepted by recognized authorities in the field . . . cannot be shown to be generally accepted as a reliable technique."24

With respect to expert opinion regarding EDR information obtained using CDR equipment, such evidence has been determined to be admissible in both criminal and civil proceedings in some jurisdictions that have addressed the issue. On the criminal side, Massachusetts recently rendered a decision (Commonwealth v.

Zimmerman) regarding the admissibility of EDR data, finding that "a party attempting to introduce expert testimony based on scientific or technical information, may lay a foundation by showing that the underlying theory is generally accepted by the relevant scientific community, or by showing that the theories relied on are valid through other means."25

www.collisionpublishing.com

In the Zimmermann case, the defendant had sought to exclude data retrieved from an EDR, asserting that the prosecution could not prove the reliability and/or accuracy of the device.26 The Appeals Court agreed with the motion judge, who after an extensive hearing on the issues, determined that the Commonwealth’s expert was qualified and that there was a "general acceptance in the scientific community of the validity of such data."27 In the end, the Court concluded that if a proper foundation was laid, such EDR data would be admissible.28 Other states have applied similar – and in some instances more restrictive - reasoning in civil cases. For example, in Illinois, a Circuit Judge admitted EDR information and related expert opinion during trial.29 On Appeal, the Court concluded that the EDR data retrieved using the CDR was "sufficiently established to have gained general acceptance" in the field of mechanical engineering or accident reconstruction.30

"" Many states have incorporated the requirement to conduct a “reasonable investigation”

Judges in New York, citing the Illinois Appeals Court, have determined that as evidence stored in an EDR system has been "generally accepted as reliable and accurate by the automobile industry and the [National Highway and Traffic Safety Administration] it should be admissible in New York".31 In New Jersey, a party seeking to admit EDR evidence must demonstrate "that EDR devices, and the interpretation of the data taken from them, is non-experimental and is demonstrable technology that the relevant scientific community widely, but perhaps not unanimously, accepts as reliable."32 The New Jersey Superior Court concluded, after an extensive review of the expert’s credentials, testimony and referenced scientific articles regarding EDRs, that EDR evidence was "not a novel technique or method" and as such should be admissible.33 The Court of Appeal in Florida came to a similar decision when determining whether data retrieved from an EDR (concerning the speed of a vehicle just prior to an accident) was admissible in a criminal action.34 The Court concluded that the process of storing crash data and its retrieval "is generally accepted in the relevant scientific field, warranting its introduction."35

D

uty to Investigate Most states have some form of statutory or decisional law which holds that an insurer’s refusal to pay a claim without conducting a reasonable investigation based upon all available information constitutes an unfair claim settlement practice. For example in California, the legislature enacted an "unfair claims settlement" statute, under which an insurer has a duty to commence a prompt investigation and to pay claims expeditiously when liability is reasonably clear.36 The Supreme Court of California recently interpreted that statute to hold that an insurer cannot deny a claim "without fully investigating the grounds for its denial."37 "To protect its insured's contractual interest in security and peace of mind, it is essential that an insurer fully inquire into possible bases that might support the insured's claim" before denying it.38

In Massachusetts, the courts have concluded that an insurer is not entitled to "ignore the results of its own investigation in assessing all evidence relative to the … claim" submitted. By essentially choosing to ignore certain evidence while believing other evidence (that is not as credible) an insurer exposes itself to a potential bad faith claim.39 A Federal court similarly found that an insurer which essentially conducted no investigation of the available facts (other than reviewing certain documents submitted by the insured), before denying coverage, violated a statute governing appropriate claims settlement practices.40 Many states have incorporated the requirement to conduct a "reasonable investigation" into their respective unfair claim settlement practice regulations. Rhode Island’s statute is a good example 41

as it holds specifically that an unfair claims practice is the refusal "to pay claims without conducting a reasonable investigation."42

Despite all of the foregoing, it should be noted that a survey of all Federal and State cases failed to reveal a single case holding that the failure to obtain EDR information was evidence of an unfair claims practice. Notwithstanding that result, such a bad faith claim could and probably will be attempted.

D

uty to Preserve Evidence (Spoliation) Inasmuch as many courts have generally accepted the admissibility of EDR information, what are the rights and/or obligations of persons/entities involved in a motor vehicle accident with respect to the preservation of EDR data? In general, people who are not themselves parties to litigation (or their agents) do not have a duty to preserve evidence for use by others. Although non-party witnesses may have evidence relevant to a case (documents, photographs, equipment, parts, etc.) and may know of its relevance, such knowledge does not create a duty to cooperate with litigants by preserving the evidence. A non-party witness is not required to preserve and store an item simply because it may be of use to others in pending or anticipated litigation.43 A duty to preserve evidence may, however, be imposed upon a non-party witness if he or she agrees to do so (contractual duty) or is served with a subpoena requiring the preservation and production of evidence (legal duty that attaches when the subpoena is served) or by virtue of a court order such as an injunction (court imposed duty).44

Conversely, individuals who are actually involved in litigation, or know that they will likely become involved, have a duty to preserve evidence for use by others who will also be involved in the litigation.45 Where evidence has been destroyed or altered by a party or someone affiliated with a party, in particular their expert witness, and another party’s ability to prosecute or defend against a claim has been prejudiced as a result, judges commonly exclude evidence to remedy such unfairness. "Trial judges have broad discretion to make discovery and evidentiary rulings conducive to the conduct of a fair and orderly trial. Within this discretion lies the power to exclude or deny expert testimony and to exclude testimony of witnesses whose case at trial is in bad faith and would unfairly prejudice an opposing party."46 Once a litigant, or its expert, knows or reasonably should know that the evidence might be relevant to a possible action, a duty to preserve such evidence arises in the interest of fairness.47 "In a civil case where an expert has removed an item of physical evidence and the item has disappeared … in such circumstances that the expert knows or reasonably should know that the item in its original

www.collisionpublishing.com

Collision 39

form may be material to litigation, the judge, at the request of a potentially prejudiced litigant, should preclude the expert from testifying as to his or her observations of such items before he or she altered them and as to any opinion based thereon."48

data is only one form of electronic information in the possession of insured vehicle owners. When an accident occurs today, most, if not all, of the following electronic devices may be present in the vehicle:

To date, there has been very limited spoliation analysis in a case involving EDR data. However in Virginia, the Circuit Court of Fairfax County heard argument on a spoliation issue in a suit filed by an individual against Ford Motor Company.49 In that case, the injured party was unable to locate the involved insured vehicle before it was destroyed.50 The Virginia Court found that Benitez (the injured party) did not breach any duty under Virginia law to preserve the vehicle (or its EDR device) since she was not the owner of the vehicle and did not have right to force the owner or any third-party to preserve it.51 Ford relied on a Federal case (Silvestri v. General Motors Corp. ) in making its argument that Benitez had a duty to preserve the insured vehicle as she knew, or should have known, that the vehicle would be relevant to her claim.53 While the Virginia Circuit Court held that the Silvestri fact pattern was somewhat similar to the factual scenario in Benitez, it was distinguishable in a number of important ways.54 For example, in Silvestri, while the plaintiff in that action (similar to Benitez) did not own the insured vehicle "in a legal sense," he, his attorney and expert had unlimited access to the vehicle.55 Moreover, Silvestri knew within a couple of weeks that he would be suing General Motors (for failure of the airbags to deploy) and yet he did not preserve the vehicle after it had been examined by his expert.56 Based on those facts and a finding that General Motors was highly prejudiced by the destruction of the evidence, the 4th Circuit Court affirmed the district court’s dismissal of Silvestri’s action.57 52

Most recently (January 5, 2010), the Supreme Court of New York ordered significant sanctions (over $15,000) against the New York Transit Authority for essentially failing to enact proper procedures to preserve crash data saved in an EDR system attached to a train.58 Although the sanctions were technically due to a failure to produce the data in a timely mater pursuant to discovery orders, it appears the delay in retrieving the evidence was, at least partially, caused by a computer memory hardware failure which was holding the information. If not for the luck of an employee unilaterally downloading the crash data onto floppy disks, the evidence would have been lost forever.59 Thus, since the evidence was not lost, the court concluded that monetary sanctions would be a sufficient remedy, but it would have considered more drastic measures if the EDR information was lost forever.60

C

onclusion Notwithstanding the present state of the law, insurers should anticipate that their rights and duties with respect to the collection of all types of electronic evidence will be evolving in the coming years. EDR

• Event Data Recorders • OnStar in GM vehicles (or a similar system) • Global Positioning Systems (Tom-Tom’s, Garmin’s, etc.)

• Mobile phones • Children’s games (with GPS/Internet capacity) • Blackberry’s • iPhones • Cameras • Video devices • LoJack (or similar vehicle recovery system) In addition to these "in vehicle" data sources, insight into the conduct of insureds, claimants and their vehicles, is also available from ATM transactions, Electronic Toll Transponders, credit card records, gas station speed passes and similar "time documenting data." Moreover, new "tracking" and "event" technologies are on the horizon.

It is likely that judges, juries and legislatures will increasingly expect law enforcement, litigants, experts and insurers to capture available electronic data. This will be especially true when an insurer (or an insured being defended by an insurer) has the burden of proof with respect to a claim or defense.

For example, assume an insurer’s Special Investigation Unit investigates an intersection accident claim. During this investigation its accident reconstructionist concludes that the insured vehicle was stopped when the crash occurred. This opinion conflicts with the testimony of the occupants of both vehicles who insist that both cars were moving at "25 miles per hour." Based upon the accident reconstruction opinion, the insurer denies all claims. Thereafter, the insured and other claimants sue the insurer for breach of contract and bad faith claims handling practices alleging that the insurer performed an inadequate investigation by not capturing CDR data when it was available.

Prior to trial, plaintiff’s counsel files a "spoliation" motion. In this motion, plaintiff argues that the insurer’s expert opinion (relating to the insured vehicle "not moving") should be excluded since the insurer knew, or reasonably should have known, that the EDR data was critical to the core questions in the case. Even if the accident reconstructionist’s opinion is not excluded by the judge, the plaintiff may still be able to argue to the jury that the insurer’s failure to retrieve this data is evidence of bad faith.

Similar motions could also be filed in third-party bodily injury cases. Assume an insured vehicle rear-ends another vehicle. The insured claims he did use his brakes and that the impact was nothing more than a "tap." Assume further that the plaintiff claims that she has severe injuries as a result of a "major impact." Assume also that the above facts come to the attention of the insurer at a point in time when the insured car, and relevant EDR data, is still readily available. Finally, assume the insurer does not seek to retrieve the EDR data and it is lost forever. Two years later, the case goes to trial and the jury awards plaintiff $100,000 while policy limits were $20,000/$40,000.

EDR data is only one form of electronic information in the possession of insured vehicle owners.

40 Collision

Under the foregoing scenario, the named insured could argue that the insurer’s failure to access and retain the EDR data is evidence of bad faith and a breach of the insurer’s duty to provide a reasonable defense. The success or failure of these Bad Faith and Breach of Contract averments would likely turn on the issue: "How critical was the EDR data?" Were there other

www.collisionpublishing.com

vehicle occupants or witnesses that would support the insured’s "minor impact" claim? Did the insurer collect and introduce other evidence that was the substantial equivalent of the EDR data (e.g., photos of the damaged cars, etc.).

While "failure to retain EDR data evidence" motions are rare at the present time, it would be short sighted to assume that this will be the case in the future. A survey of recent statutes and decisions, as well as information generally available on the internet, reveals that EDR evidentiary issues are receiving remarkable attention. This will invariably lead to an increased number and variety of legal challenges.

There is also be noted that initiatives currently being undertaken by some automobile insurance carriers to access and retain EDR type data could place more pressure on an insurer to establish guidelines concerning electronic evidence collection. For example, one particular program asks policyholders to volunteer to have their driving electronically monitored in exchange for a usage based discount.

Lastly, it is evident that the trend in many civil and criminal matters involving experts and electronic evidence in the presentation of "expert witness foundation" and "evidence spoliation" is toward more challenges. In light of the foregoing, it would be prudent for insurers to develop some limited training standards and best practice procedures for the collection of electronic evidence in those limited circumstances where such information can reasonably be expected to be critical for a claim on defense.

R

eferences: 1. National Highway Traffic Safety Administration, Docket No. NHTSA-2004-18029, RIN 2127-A172.

2. Arkansas (A.C.A. §27-37-103);California (Ca. Veh. Code §9951); Colorado (Colo.Rev.Stat. 12-6-402); Connecticut (Conn. Gen. Stat., § 14-164aa); Maine (29-A M.R.S., §§ 1971 – 1973); Nevada (Nev. Rev. Stat. Ann. § 484.638); New Hampshire (RSA 357-G:1); New York (NY CLS Veh & Tr § 416b); North Dakota (N.D. Cent. Code, § 51-07-28); Oregon (ORS § 105.932); Texas (Tex. Transp. Code § 547.615); Virginia (Va. Code Ann. § 46.2-1088.6).

3. Washington Substitute Senate Bill 5574, 61st Legislature, 2009 Regular Session (2009 Bill Text WA S.B. 5574).

4. Connecticut Conn. Gen. Stat., § 14-164aa; Maine 29-A M.R.S., §§ 1971 – 1973; New York NY CLS Veh & Tr §416-b.

5. Arkansas A.C.A. §27-37-103; New Hampshire RSA 357G:1; North Dakota N.D. Cent. Code, §51-07-28; Oregon ORS §105.932; Washington RCW 48.30.015; RCW §46.63.020.

6. California Ca. Veh. Code §§ 9950-9953; Colorado C.S.R. 126-402; Nevada Nev. Rev. Stat. Ann. §484.638; Texas Tex. Transp.

Code § 547.615; Virginia Va. Code Ann. §46.2-1088.

7. Conn. Gen. Stat., § 14-164aa.

8. 29-A M.R.S., §§ 1971-1973.

9. ORS § 105.932.

10. 29-A M.R.S., § 1972.

11. A.C.A. § 27-37-103.

12. Va. Code Ann. § 46.2-1088.6.

13. C.S.R. 12-6-402.

14. 2009 Bill Text WA S.B. 5574.

15. RSA 357-G:1; 2009 Bill Text WA S.B. 5574.

16. See Imperiali v. Pica, 338 Mass. 494, 498 (1959); Polito v.

Galluzzo, 337 Mass. 360, 364-365 (1958).

17. Darcy v. Hartford Ins. Co., 407 Mass. 481, 488 (1990); citing Morrison v. Lewis, 351 Mass. 386, 390 (1966). See also 14 G. Couch, Insurance, § 51.107, at 607 (2d ed. 1982).

18. Darcy, at 488.

19. Hager v. Gonsalves, 398 N.J. Super. 529, 538; 942 A.2d 160, 165 (2008); citing Solvents Recovery Service v. Midland Ins. Co., 218 N.J. Super. 49, 55; 526 A.2s 1102 (1987).

20. State Farm v. McSpadden, 88I11 App. 3d, 1135; 411 N.E.2d 121, 124 (1980).

21. Rochon v. The Preferred Acc. Ins. Co., 118 Conn. 190, 198, 171A. 429, 432 (1934).

22. Belz v. Clarandon America Ins. Co., 158 Cal. App. 4th 615, 631-632, 69 Cal. Rptr. 3d 864, 874 (2007); citing Clemmer v. Hartford Ins. Co., 22 Cal. 3d 865, 883, 151 Cal. Rptr. 285 (1978).

23. Frye v. United States, 54 App. D.C. 46, 293 F. 1013 (1923).

24. Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 592593; 113 S.Ct. 2786, 2796 (1993).

25. Commonwealth v. Zimmerman, 70 Mass. App. Ct. 357, 360; 873 N.E.2d 1215, 1218 (2007) quoting Commonwealth v. Patterson, 445 Mass. 626, 640 n.11 (2005); see also Commonwealth v. Lanigan, 419 Mass. 15, 26 (1994).

26. Id. at 359.

27. Id. at 360.

28. Id. 29. See Bachman v. General Motors Corp., 332 Ill. App. 3d 760, 765 (2002).

30. Id. at 779 quoting Frye v. United States, 293 F. 1013, 1014 (D.C. Cir. 1923).

31. People v. Christmann, 776 N.Y.S.2d 437, 442 (2004).

32. State of New Jersey v. Shabazz, 400 N.J. Super. 203, 210 (2005).

33. Id. at 218.

34. Matos v. State of Florida, 899 So. 2d 403, 2005 Fla. App. LEXIS 4359 (2005).

35. Id. at 407, 2005 Fla. App. at *10.

36. Ca. Ins. Code §790.03.

37. Wilson v. 21st Century Ins. Co., 42 Cal. 4th 713, 720 (2007); quoting Frommoethelydo v. Fire Ins. Exchange, 42 Cal.3d 208, 215 (1986).

38. Id. at 721; quoting Egan v. Mutual of Omaha Ins. Co., 24 Cal.3d 809, 819 (1979).

39. Bohorquez v. Metropolitan Prop. & Cas. Ins. Co., 2000 Mass. App. Div. 226, 228. See also, Tallent v. Liberty Mutual Ins. Co., 19 Mass. L. Rep. 460 (2005).

40. Id. 33.

41. Federal Ins. Co. v. HPSC, Inc., 480 F.3d 26 (1st Cir. 2007).

42. R.I. Gen. Laws § 27-9.1-4.

43. Fletcher v. Dorchester Mutual Insurance Co., 437 Mass. 544 (2002).

44. Nally v. Volkswagon of America, Inc., 405 Mass. 191 (1989).

45. Id. 46. Bolton v. Massachusetts Bay Transportation Authority, 32 Mass. App. Ct. 654, 657 (1992).

47. Kippenhan v. Chaulk Serve, Inc., 428 Mass. 124, 127 (1998).

48. Id; See also Carbone, et al. v. Checker Taxi Co., et al., 3 Mass. L. Rep. 240 (Superior Court 1994) (Cab company expert, who destroyed throttle cable, precluded from testifying about his observations and testing and jury was instructed that had cable been offered as evidence, it would have disclosed facts adverse to cab company).

49. Benitez v. Ford Motor Co., 68 Va. Cir. 156 (2005), affirmed by 273 VA. 242 (2007).

50. Id. 51. Id. 271 F.3d 583 (4th Cir. 2001).

52. Silvestri v. General Motors Corp., 271 F.3d 583 (4th Cir. 2001).

53. Benitez, 68 Va. Cir. at 156.

54. Id. 55. Id. 56. Id. 57. Id. 58. Williams v. New York Tr. Auth., 2010 NY Slip Op 50011U. 59. Id. at *4.

60. Id. at *5

www.collisionpublishing.com

Collision 41

Drawing First, Animation Second What good is animation if you can’t create an accurate diagram?

THE CRASH ZONE It seems that everyone is excited about animation these days, but you can’t create a reliable animation without first having an accurate, detailed diagram of the crash scene. That’s where The Crash Zone excels! It has all the tools you need to draw courtroom-accepted, crash and crime scenes using mathemetically accurate, CAD technology.

And, The Crash Zone also does animations!

Faster Diagrams - Use your accurate measurements with the drawing tools like this Easy Intersection wizard to document any crash scene.

We spent the last 18 years making it easier for you to draw and edit in the Crash Zone. That means now you can get your job done faster!

No hidden fees FREE technical support and NO annual maintenance!

More accurate, CAD-based!

Faster 2D drawing and editing!

Easier 3D surfaces and curves!

Powerful intersection builder!

Unique 3D body poser!

Thousands of symbols and lines!

Vehicle Specs database!

Crash Calculation Wizards!

Supports laser measurements!

Measurement-based animation!

Easier 3D - Just one mouse click lets you view any 2D scene as a 3-dimensional model! Easy-touse tools let you create accurate 3D surfaces, curves, roofs, ramps, stairs, signs, and more

Accurate Animations - Crash Zone animations are based on your physical measurements, so you know they are accurate! Special animation tools make it easy to animate any symbol in 2D and in 3D.

Want to learn more? Call 1-877-769-5554 or visit: www.cadzone.com

Back to Table of Contents

d e s s e r p Sup George Hall P.E. Hall Consulting

44 Collision

www.collisionpublishing.com

A

bstract A 2-vehicle fatal collision occurred in Oklahoma in August 2006 when the driver of a General Motors (GM) pickup crossed the center line and collided with a passenger sedan.

The driver of the sedan died from the collision and the driver of the pickup was charged with manslaughter. As part of the investigation by law enforcement, the GM Sensing & Diagnostic Module (SDM) was downloaded using version 2.8 of the Bosch Crash Data Retrieval (CDR) software. A paper copy of the CDR report was included in the investigation file, and the downloaded file was kept on the officer’s field computer.

The author was retained by defense counsel to assist in understanding what the public refers to as the "black box" data. The author immediately advised counsel to obtain a copy of the original down-

loaded CDR file. The defense subsequently requested a copy of the CDR file and it was eventually discovered that the file had been lost. The defense then moved to suppress the CDR evidence, and a hearing was held to argue the motion. From the time of the download till the hearing, the CDR software had advanced by 5 versions. The defense argued that it needed the downloaded file so as to be able to examine it using the latest version of the software. The defense further argued that the CDR report printed at the time of the download should be suppressed as evidence since the software advances could yield a different report if the original CDR file were available for examination in the latest version of the software. The court agreed and sustained the defense motion to suppress, thereby preventing the CDR report from being admitted as evidence. This finding has significant implications for everyone involved with this technology.

www.collisionpublishing.com

Collision 45

C

ase Background.

A 2-vehicle collision occurred in Oklahoma in August 2006 when the driver of a 2000 GM pickup crossed the center line and collided with a 1993 Plymouth Cobalt sedan. The driver of the sedan died as a result of the collision. Figure 1 is taken from the official Oklahoma collision report and shows the collision incident. Vehicle 1 is the 1993 Plymouth Cobalt sedan and Vehicle 2 is the 2000 General Motors pickup.

The following is a timeline showing significant aspects of this case from the author’s perspective: • • • • • • •

C

Figure 1. Collision Scene.

As shown in Figure 1, the driver of the GM pickup initially drifted off the road to the right, overcorrected and went into a yaw, then crossed the center line and collided with the sedan. As part of the investigation by law enforcement, the GM SDM was downloaded using software version 2.8 of the Bosch CDR system. The speed limit at the scene of the collision was 45 mph and the CDR report from the GM pickup indicated a speed of 74 mph at the "minus 5" time value. The driver of the GM pickup was subsequently charged with manslaughter. A paper copy of the CDR report was included in the investigation file, and the downloaded CDR file was kept on the officer’s field computer. Figure 2 is a table scanned from a paper copy of the CDR report which shows the pre-crash data recorded by the SDM.

"

Aug 2006 – Collision Aug 2006 – CDR download (5 days after the crash) Apr 2007 – Author retained as defense expert, recommended obtaining the CDR file Dec 2007 – Obtained electronic files from state, no CDR file was included Jan 2008 – discovered CDR file was lost Dec 2008 – Hearing on defense Motion to Suppress CDR evidence Jan 2009 – Court rules to suppress CDR evidence

DR File Lost The author was retained as an expert for the defense in April 2007, approximately 8 months after the collision. Vehicle Event Data Recorder (EDR) information is a relatively new technology to the legal community, and the author was retained primarily to evaluate the data and assist defense counsel in understanding it. In addition to the usual documentation dealing with the collision incident, the author was provided with a black & white paper copy of the Bosch CDR report. The GM pickup had been salvaged and hence was unavailable for the author to download. The author recommended that defense counsel obtain a copy of the downloaded CDR file for evaluation using the latest CDR software, and that request was made to the prosecution. The request to obtain the CDR file as submitted by defense counsel read specifically: "Copy of the actual download files from the "black box" information taken from the defendant’s vehicle, sometimes known as the CDR file. " While the use of the term "black box" is technically incorrect and frowned upon by the expert community, it is effective in conveying the meaning to non-experts. In addition to the CDR file, the mapping files from the survey of the scene were also requested. In December 2007 defense counsel provided the author with electronic files received from the state, but they consisted only of mapping data and the CDR file was not present. After some back and forth between the attorneys, in January 2008 it was discovered that the CDR file had been lost and the paper copy of the report was the only CDR related evidence remaining. Defense counsel filed a Motion to Suppress the paper copy of the CDR report; in other words, defense counsel asked the court to prevent the paper copy of the CDR report from being admitted as evidence.

A hearing was scheduled for December 2008 to argue the Motion to Suppress the paper copy of the CDR report.

Figure 2. Pre-Crash Data.

Documentation in the police investigative report indicates that the CDR download was performed under authority of a search warrant.

Documentation in the police investigative report indicates that the CDR download was performed under authority of a search warrant. Further documentation indicates that the CDR information was included on an "Evidence List and Chain of Custody" form.

There is no mention of specifics regarding chain-of-custody transfers of the CDR file and later testimony indicated that the file was simply kept on the officer’s field computer.

46 Collision

It isn’t difficult to imagine how the CDR file could have been lost; or for that matter, how any such digital file can be lost. Computer data must be regularly backed up to insure against loss. In this particular incident, it appears that the only copy of the CDR file was the one that existed on the officer’s field computer. The hard drive on the officer’s field computer failed some months after the download. Attempts to salvage the hard drive were later made by computer experts, but they were unsuccessful. In addition to hardware failures, files can be lost by intentional deletion to create more space. Police computers may be re-assigned to other officers and their contents may be deleted as part of the process of setting up the computer for another purpose. Regardless of the reason, it should be clear that computer data will eventually be lost if it is not backed up.

www.collisionpublishing.com

W

hy is the CDR File Needed?

The Bosch CDR software version 2.8 was used to download the file and to generate the report in August 2006.

Prior to the hearing in December 2008, the CDR software had advanced by 5 versions (versions 2.81, 2.9, 2.91, 3.0, & 3.1). Each new version brought changes to the software, some of which could be characterized as significant. Each new version of the software may include functional changes, fixes to identified software "bugs," changes to the format of the report output, and additional capability to interpret the data contained within the airbag control modules (ACM). Some of the changes to the software have been detailed very specifically and are contained in the "readme.txt" file that accompanied new releases from version 1.0 through version 3.0. For example, the change "added 8 second brake switch data" is a specific change that informed users would understand. However, some changes are noted only very generally and the user has no way of knowing exactly what the change comprised. For example, the change "updated data limitations for GM vehicles" does not tell the user anything specific about the changes made, but it does tell the user that the Data Limitations section of the CDR report for at least some GM vehicles will now be different than it previously was. In that case, the only way to determine if there were any changes to a specific GM vehicle CDR report is to open the data file using the latest version of the software and compare the CDR report output with the output from the older software version. Commencing with version 3.1, changes to the software can be found in the "What’s New" section of the Help file.

Because there is an ongoing process of improving the software and eliminating "bugs" that may discovered, it is imperative that the user always utilize the latest version of the software to open the data file and interpret the data. Otherwise, it is possible that the software may not correctly interpret the data file. Commencing with version 3.1 the software includes this notice on the first page of the report; "IMPORTANT NOTICE: Robert Bosch LLC recommends that the latest production release of Crash Data Retrieval software be utilized when viewing, printing or exporting any retrieved data from within the CDR program. This ensures that the retrieved data has been translated using the most recent information including but not limited to that which was provided by the manufacturers of the vehicles supported in this product."

An example of a change in the Data Limitations section can be seen regarding the status of the driver’s seat belt in GM vehicles as shown in version 2.61 vs. version 2.81. In version 2.61 the statement in the Data Limitations section states "Driver’s Belt Switch Circuit Status indicates the status of the driver’s seat belt switch circuit."

This is a very straightforward explanation of this data field. However, contrast this with the statement from the Data Limitations section in version 2.81 which states "Driver’s Belt Switch Circuit Status indicates the status of the driver’s seat belt switch circuit. If the vehicle’s electrical system is compromised during a crash, the state of the Driver’s Belt Switch Circuit may be reported other than the actual state." With version 2.61 we could conclude that the driver’s seat belt was either buckled or not dependent on the CDR report. However, changes made to version 2.81 indicate that this data field may not be reliable if the vehicle’s electrical system was "compromised" during a crash. This may drastically change the meaning and our interpretation of the data field regarding whether or not the driver’s seat belt was buckled in a given case.

An example of a functional or operational change occurred commencing with version 3.1 software. Prior to this version, the GM power booster was recommended to be used for all downloads of both GM and Ford vehicles. However, commencing with version 3.1 of the CDR software, the GM power booster is only recommended for certain GM vehicles. This change affected the way that users actually operated the equipment.

In addition to keeping the file original CDR so that it can be opened and evaluated using the latest version of the software, there are other reasons that the CDR computer file is needed in place of a paper copy of the CDR report. Paper reports are easily modified. "Liquid paper" or other such products can be used to erase values on a paper report such that the erasure isn’t noticed when the report is copied again. Although they may look genuine, paper reports can’t be verified as having been produced by the CDR software. The computer operating system includes a date/time stamp when a new file is created or an existing file is modified. This date/ time stamp provides an audit trail regarding the file; if the CDR file is lost, then so is this audit trail. The airbag module type isn’t listed in the CDR report, but it can be determined by opening the CDR file with a text editor as shown in Figure 3. Figure 3 shows a CDR file that has been opened in the Microsoft Notepad text editor, and shows that the module is an SDMG2000 type.

Figure 3. Module type identified with text editor.

The CDR software can produce an Adobe Portable Document Format (PDF) report file that can be distributed for convenient access by others who do not have access to the CDR software. However, the PDF computer file is not a substitute for the downloaded CDR file. The PDF file can’t be used to determine module type and it can’t be re-evaluated using updated CDR versions. It should also be noted that PDF files can be modified. Software exists to convert PDF files into other formats such as Microsoft Word. Once converted, the report values can easily be changed and the report can then be saved back to a PDF file. The following points summarize the need to keep the CDR file: • • • • •

File can be re-evaluated using updated versions of the CDR software The CDR file is needed to verify that a paper report originated from the CDR file Computer files have a date/time stamp that creates an audit trail The module type can’t be determined without the CDR file PDF files can also be modified

H

istory Of Software Changes Since the CDR software first debuted some 10 years ago, there have been 47 known versions from the original version 1.0 (February 2000) to the current version 3.4 (January 2010). The CDR software and hardware was originally developed by the Vetronix Corporation. Vetronix was purchased by Bosch, and Bosch now maintains the software and associated hardware. The software is an application that downloads and interprets the data contained within vehicle electronic control modules and provides a report of the interpretation. Because this is a cutting edge application, the software has undergone numerous changes and improvements.

Included with this issue is a CD that has a file titled "CDR-Version-History." This file contains a listing of all the known versions

www.collisionpublishing.com

Collision 47

of the CDR software and the changes that were made to each version. As relates to the Oklahoma case, the pertinent versions are those showing the changes that occurred between version 2.8 and version 3.1. For example, version 2.9 allowed an additional 3 seconds of braking data to be displayed in the report. This is a very significant change that knowledgeable users would understand.

Amongst other changes, version 3.0 updated the Data Limitations for GM air bag control modules. This is a general change that can only be evaluated by comparing the Data Limitations sections of reports produced by earlier versions with the report produced by version 3.0. These examples illustrate the primary reason for keeping the CDR file, which is to allow the file to be evaluated using the latest version of the CDR software. The following bullet points include some of the significant changes made by newer versions of the CDR software. The list is admittedly subjective, and others might argue that significant changes occur in other versions than shown below.

CDR 1.0 issued Feb 2000 1.66, Oct 2002 • The term "near deployment" was changed to "non-deployment" 2.0, Feb 2003 • added Ford vehicles • pdf report output 2.8, Nov 2005 • Engineering Translation Report, certain GMs • CAN bus cables 3293, 3320, 3321 required new hardware interface 2.9, Jan 2007 • Additional 3 secs pre-crash braking for GM (8 secs total) • Rollover module support on some GM (hex data only via DLE) • Side airbag deployment data became available for certain GM 3.0, Jan 2008 • Chrysler coverage • Ford PCM downloads • GM Rollover Sensor support 3.1, Dec 2008 • Warning notice added to 1st page of CDR reports • 3 more secs of pre-crash data available on certain Chryslers • Notice that it may be necessary to re-image some Chrysler ACMs to get additional data

C

ourt Hearing on the Motion To Suppress A hearing was held in December 2008 in state court for arguments on the defense motion to suppress the CDR evidence. The state admitted that the CDR computer file had

been lost and that attempts to recover it had been unsuccessful.

The prosecution introduced an expert witness and presented the position that the paper copy of the CDR report was adequate and should stand alone without the CDR computer file. The author testified as an expert witness for the defense and opined that the CDR computer file was necessary to properly evaluate the data using the latest software. The issues regarding the necessity for having the computer file can become rather complex and difficult to explain in the environment of a courtroom. Much of the reasoning discussed above in the "Why is the CDR File Needed?" section was presented to the court. After the hearing was concluded, the court took approximately 1 month to issue the following ruling (capitalization is as appeared on the order): "IT IS THEREFORE ORDERED, ADJUDGED AND DECREED, that the Motion to Suppress of the Defendant, as to the crash data module information should be and the same is hereby sustained."

Using simpler terminology, the court agreed with the defense that the CDR paper report should not be admitted as evidence. Some of the logic used by the Court to arrive at this decision is pertinent for the education of professionals involved with this technology.

For instance, as shown in this excerpt from the court’s decision, it is clear that the court understood the need to use the latest version of the software to interpret the CDR file: "The Court is satisfied by clear and convincing evidence, free from unmistakable doubt based upon the testimony of the experts that by reason of subsequent updates to the software services that there is a high potential that additional information could have been obtained if this information had been provided and retained and not lost."

It’s important to note that while the court understood that there was a potential for obtaining additional data using the latest software, there is no mention that the data might have been favorable to the defendant. The data may have been favorable to the defendant, or it may not. The point is that the court’s ruling was based on the fact that loss of the computer file constituted a loss of evidence. The court realized that the paper copy of the CDR report produced by an older version of the software was not equivalent to having the computer CDR file. Additional clarification of the court’s logic regarding the loss of the CDR computer file can be seen from the excerpt below: "The state did not make a bonafide good faith effort to maintain the integrity so it could be tested by the defense and it is even heightened ten times by the fact that these additional updates could have obtained more information that could have been highly relevant."

As is often the case with lost evidence of any type, the party who lost the evidence is looked upon unfavorably by the court. As shown by the excerpt above, the court recognized the importance of having the computer file available so that it could be evaluated by the defense. It’s worth noting that the court emphasized with the "heightened ten times" phrase that it understood the importance of having the computer file available so that it could be opened with the latest software update. Also worth noting is the fact that the court used the phrase "could have been highly relevant" with regards to data that might have been obtained using the latest software version. The court did not conclude that any new data from a report produced by the latest software would have been relevant, only that it could have been relevant and it didn't specify whether it would be relevant for one party of the other.

The state admitted that the CDR computer file had been lost and that attempts to recover it had been unsuccessful.

48 Collision

www.collisionpublishing.com

O

" "

ther Potential Issues Related to the Court’s Decision The court’s decision relates only to the computer CDR file. Early in the development of this technology, there existed an argument among users as to whether or not it was necessary to harvest and preserve the electronic module(s) that contained crash data or whether it was sufficient to just download the data file and preserve it. The prevailing viewpoint has been that downloading and preserving the data file is sufficient and that it is not necessary to harvest and preserve the electronic module(s). However, this viewpoint was challenged by the recent introduction of Chrysler vehicles as part of the version 3.0 software release. Chrysler vehicles that were imaged (downloaded) using version 3.0 software did not capture all of the available data, and it was necessary to re-image these vehicles using version 3.1 software (to capture all the available data). If the vehicle was no longer available when the version 3.1 software was released, then it would not be possible to re-image unless the module had been harvested and preserved. The prevailing thought is that this was a "one off" situation brought on by the introduction of a new manufacturer’s vehicles to the CDR system, and that it isn’t necessary to harvest and preserve electronic module(s). However, one can envision the possible legal entanglements brought about by loss of evidence that occurred from not harvesting the module.

The available training courses emphasize the need to preserve the CDR file.

This line of reasoning can be expanded even further to include an argument as to whether one should preserve the entire vehicle so as to prevent any "loss" of evidence. When the CDR technology was first introduced, the only module that contained retrievable event data was the airbag control module (ACM) in GM vehicles.

Some Ford powertrain control modules (PCM) contain data that is now retrievable by the CDR system, and some GM rollover sensors (ROS) also contain data that can now be retrieved by the CDR system. The amendment to Chapter V of Title 49 of the Code of Federal Regulations (49 CFR Part 563) is scheduled to become effective for model year 2013 vehicles, and specifies the type of data that must be recorded by vehicles with EDRs. However, 49CFR563 does not specify which module(s) records the data. Between now and the enactment of 49CFR 563, it is likely that new vehicle manufacturers will be added to the CDR system. Some practitioners have been harvesting and preserving module(s) from collision vehicles that are currently unsupported in anticipation that they may later be supported by the CDR system. The obvious question relates to which module(s) should be preserved. While the ACM and PCM are obvious candidates for most vehicles, there may be data contained in other module(s) as well. Failure to preserve the entire vehicle, or at least to harvest all the electronic modules that may store data, could be considered as a "loss" of evidence. It should be noted that the author is an engineer and does not claim to have any legal expertise, and that this discussion of "potential" legal issues is presented only for your consideration as a professional involved with the CDR technology.

C

onclusion The defendant in this case was originally charged with manslaughter. Some time after the court ruled to exclude the CDR evidence, the case was settled by the defendant agreeing to enter an alcohol treatment program. This court decision will be considered by others. It is likely that other "lost CDR file" cases will arise as the technology expands to include more vehicle manufacturers and models. The available training emphasizes the need to preserve the CDR file. Figure 4 is a slide from the CDR Technician course as taught by certified Technician Trainers.

Procedures (SOPs) may already exist that include backups and archiving of computer files, but these procedures must be effectively communicated to field personnel. If SOPs don’t already exist to ensure that CDR files are preserved, then they should be developed. Engineering firms often have a "Quality Assurance" manual that contains protocols for archiving and storing computer data.

As with law enforcement agencies, it is imperative that field personnel from engineering firms be made aware of the necessity to backup and archive original CDR computer files.

Figure 4. Slide from the Collision Safety Institute's Standardized Technician Training Course.

The lessons learned from this case regarding the necessity of keeping the original CDR computer files can be extrapolated even further. For example, it isn’t difficult to envision a corollary situation regarding data files from mapping instruments. Total station survey instruments and Global Positioning System (GPS) instruments both create data files which are used by Computer-Aided Drawing (CAD) software to create maps. Failure to maintain these computer files for examination by the opposing party could be cause for a motion to suppress the maps from being admitted as evidence.

This could then conceptually cascade to include suppressing momentum and/or energy analyses that were based on distances determined from the maps and to suppressing animations and/or simulations that were based on the maps and the momentum and/ or energy analyses. Electronic data files from test instruments should also be archived and maintained. Examples include data files from recording radar or accelerometers used for brake or acceleration testing.

Professionals involved with the CDR technology need to develop procedures to preserve the downloaded files. Loss of the downloaded CDR file may result in the CDR evidence being excluded from trial, even if a paper copy of the CDR report exists.

Note the question in Figure 4 regarding preservation of the data.

Several other slides in the CDR Technician course also discuss the importance of saving the data. Law enforcement agencies should consider their procedures for saving and archiving the original CDR file so that it is available for all parties. Standard Operating www.collisionpublishing.com

Collision 49

Back to Table of Contents

I

ntroduction Since the introduction of the aviation flight data recorder in late 1940s, surface transportation safety officials have focused on the idea that collecting objective information about crashes serves to promote and support a better and more thorough understanding of roadway crash events which may not otherwise be easily explained. In the mid1990s, drawing on, at that point, nearly 50 years of experience with and evolution of the aviation application of what became known in the common vernacular as “black boxes” in aircraft, the US National Transportation Safety Board (NTSB) and the National Highway Traffic Safety Administration (NHTSA) began urging the manufacturers of light surface vehicles to develop a plan to gather better crash pulse data in an effort, for the most part, to better evaluate the performance of advanced restraint systems.1 In the mid-1990s, airbags or their equivalent had been in light vehicles to one degree or another since the introduction of the GM “Air Cushion Restraint System” in 1974 but auto manufacturers like General Motors (GM) and Ford had only then (in the mid-90s) started to affirmatively work toward the inclusion

50 Collision

of advanced data collection capabilities within their various systems, specifically within their airbag control modules (ACMs).

The larger societal safety effort justifying the introduction of a technology similar to that found in aircraft into the surface vehicle fleet was described by Chidester, et al1 in 1999 (although primarily as it related to General Motors vehicles at that time) with the idea being that a wider introduction of what would become know as the “Event Data Recorder” (EDR) capability or functionality would lead to (1) improved airbag sensing systems, (2) improved roadway design, and (3) more meaningful motor vehicle safety regulations.

While there was no direct mention of it in Chidester1, the “3 Es of Traffic Safety” are, of course, “Education, Engineering and Enforcement,” the natural byproduct of any system which would gather objective “real-time” information about a crash would be that the data would find its way into the analysis of crashes for litigation; whether civil or criminal (the Enforcement “E” in the triad).

www.collisionpublishing.com

AN ABBREVIATED HISTORY OF

CDR TECHNOLOGY

Rusty Haight Collision Safety Institute

www.collisionpublishing.com

Collision 51

While Chidester1 addressed the broader research and regulatory advantages of collecting objective crash data (the Engineering and Education “Es”), it was clear that crash reconstructionists would find that their traditional methods of analysis would be supplemented by the objective data or, in some cases, their analysis would be subject to further review or scrutiny as a function of conflict - whether real or interpretative - with crash data recovered from those vehicles.

The Vetronix Corp (then of Santa Barbara, California) had long been involved with General Motors developing first the “Tech 1” and later the “Tech 2” for use by GM dealership and factory service personnel. The latest incarnation of the tools in that line is the “Tech 2” - an advanced “scantool.” A “scantool,” in this context, is typically a hand-held computer which can communicate with on-board computers in a light vehicle and read diagnostic trouble codes (DTCs), and data lists. It can be used to command or implement vehicle functions or to program or re-program one or more of the light vehicle electronic control units (ECUs) with new instruction sets or functional parameters.

Most vehicle manufacturers have OE-specific scan tools for diagnostic, repair and maintenance functions and the Tech 2 was the device designed and built for GM by Vetronix primarily for GM dealerships and factory service personnel. Ultimately then, when

GM began including crash data collection capabilities in their production vehicles, they turned to their supplier for the Tech 2 Vetronix - to develop what would become a more specialized and later wider reaching type of scantool: the “Crash Data Retrieval” (CDR) System.

When introduced as publicly, commercially available in 20002, the Vetronix Crash Data Retrieval System ushered in a new era of crash reconstruction possibilities impacting long standing techniques, applications and methods. While widely and persistently described as a “supplement to a traditional crash reconstruction3,4, it was clear early on that the system would have a long lasting impact on crash analysis in the public and private sectors alike.

While the reader is assumed to have developed some skills as a crash investigator and reconstructionist, in practical application, the reader is also presumed to be familiar - at least generally - with evolution of light surface vehicles5 in the period between the mid 1990s and 2009. Meaning, this chapter is developed with an assumption that the reader recognizes that passenger cars, light trucks and SUVs (“light surface vehicles:” those under 8,500lbs/3,855kg GVWR5) are very different in model year 2009 than they were, for example in model year 1999 and that the evolution of technology related to these light vehicles will continue to change over time in response to a variety of factors and competing interests from regu-

Figure 1: The components of the CDR system in 2000.

52 Collision

www.collisionpublishing.com

lation to the environment to consumer demand. For that reason, this narrative is offered as a single-point-in-time snapshot of the technology as it exists up to this writing and it should be understood that, as light vehicles evolve into the future, some of what is described here may no longer be applicable or hold true across a broader range of those future vehicles yet to be conceived, designed or built. While similar in many ways and very different in many others, recorded crash data found in heavy vehicles is addressed separately.

structionists throughout North America but the data was limited to that found in GM vehicles (at that point those in essentially MY1995 through MY2002). The system components were initially relatively few but as the system and coverage has evolved, so, too, has the complexity and sheer volume of the tool’s components. Figure 1 shows the original components of the CDR system (except for the added laptop computer) and Figure 2 depicts the system as it has evolved going into 2007. For comparison, Figure 3 depicts the CDR system as it is shipped in late 2009.

he Evolution Of The Crash Data Retrieval System When introduced in 20002, the Vetronix Crash Data Retrieval (CDR) System became, almost overnight, the subject of conjecture and concern that traditional reconstruction would be a thing of the past. Bullet points like “A vehicle's "black box" will help claims adjusters reconstruct a crash6” lead some to believe electronically stored crash data would mean the end of traditional crash analysis. However, reasoned and tempered end-user training4, presentations and other public information3,7 reinforced the underlying concept that remains in place today: the light vehicle crash data - while otherwise normally objective and reliable - is subject to conditions and limitations that should be considered when applying that data to a given crash. As with any crash analysis, having as thorough an understanding as possible of the roles of the human, vehicle and the environment is fundamental to competently evaluating the crash and, in this context, properly interpreting and applying the recorded crash data.

In March of 2003, almost 3 years to the day after announcing the initial release of the CDR System, Vetronix announced8 the added ability to access data in select Ford vehicles. Limited at the time to a relatively small group of vehicles, that move nonetheless expanded the apparent immediate and future usefulness of the CDR System in many ways. Later that year, industrial giant Robert Bosch, GmbH bought Vetronix9 and took over development of not only the Tech 2 and other diagnostic and test systems but also the CDR System.

T

In the first three years of commercial availability (2000-2003), the Vetronix CDR System enjoyed wide acceptance and use by government agencies including the NHTSA, NTSB, Transport Canada (TC) and others including police agencies and private crash recon-

Between 2003 and 2007, Bosch continued to expand the CDR System’s reach and application including adding access to data found in more GM vehicles and access to more Ford vehicles. In late 2007, the Bosch CDR System expanded to include access to GM RollOver Sensors (ROS) and Ford Powertrain Control Modules (PCM). But perhaps the biggest news as it related to the CDR System in 2007 was the addition of access to data in Chrysler vehicles. Going into 2008, the CDR system was capable of accessing stored crash related data in roughly half of all the vehicles sold in North America since model year 2004. But WHERE is and WHAT is that data?

Figure 2: The components of the CDR system in 2008.

www.collisionpublishing.com

Collision 53

W

Figure 3: The components of the CDR system in 2009.

hat Is “Crash Data?”

In the context of light vehicles - passenger cars, light trucks and SUVs - “crash data” is dynamic, time-series data captured for/in one of these vehicles during the period just prior to or during a crash as a function of some physical occurrence “observed” by the appropriate sensor(s) installed in that vehicle. It’s objective information stored in a module or ECU - or a combination of more than one of those for a given vehicle - after a trigger threshold has been met or exceeded.

As part of this chapter, one will find a glossary of terms commonly encountered as they relate to what we will call here “CDR technology.” The terms, words, acronyms and phrases found in the glossary are drawn from those commonly found in the automotive industry, and crash reconstruction as well as those drawn from 49CFR563.510 and as found the CDR System program’s Help File.

While it’s been used in this chapter often up to this point, one of the first acronyms that should be addressed in some detail is “CDR.” As properly used in this technology, and as previously used in this chapter, we can see it refers to the Bosch “Crash Data Retrieval” (CDR) System. Often, it is seen misused by those unfamiliar with the technology, untrained or improperly trained to describe some sort of “crash data recorder” or seen as the sentence: “crash data recorder in cars, like a ‘black box’,” suggesting that there is a single, specific device or devices found in light vehicles which has/have, as its primary purpose, a specific recording function related to crashes. Such is not the case in this technology as it relates to light vehicles accessible by the Crash Data Retrieval System. It’s important to be clear, as it relates to the data which might be accessible using the Vetronix and more recently Bosch Crash Data Retrieval System, there is no independent “crash data recorder.”

54 Collision

Another frequently misused term is “EDR” or “Event Data Recorder.” An “Event Data Recorder” is a “device or function in a vehicle that records the vehicle’s dynamic time-series data during the time period just prior to a crash event (e.g., vehicle speed vs time), or during a crash event (e.g., delta-V vs time) intended for retrieval after the crash event.”10 While the definition is broad enough to include a device installed with the specific design intent of recording data related to crash events, in practical application, for Bosch CDR System accessible vehicles, there is no stand alone, independent device tasked with “recording dynamic time-series data.” As it is applied in this technology, then, there are several specific, clearly identified electronic control units (ECUs) identified as (1) airbag control modules (ACM), (2) rollover sensors (ROS) and (3) powertrain control modules (PCMs) all of which have vehicle or system control capabilities as their primary design functions and the potential for data recording as a supplemental function.

When certain trigger thresholds are met - thresholds which vary from module-to-module and by supplier and manufacturer-tosupplier and manufacturer - a given, specific ECU may initiate internally an “event data recorder” (EDR) functionality or associated capability. The important distinction is; however, that none of these ECUs has, as their primary function that “EDR” task or function 1,3,4,6.

To refer to an airbag control module such as those seen as Figure 4, a GM ROS as seen in Figure 5 or a Ford PCM as seen in Figure 6 as an “EDR” is not only inaccurate, it’s technically incorrect and arguably misleading. In another sense, it may create further confusion when - in situations where certain trigger thresholds may not be met - the subject ECU does not record “event” related data. In that case, the uninitiated may wonder why some “event data recorder” ... well, didn’t. Clarity, specificity and accuracy are

www.collisionpublishing.com

the cornerstones of good communication and here, with so many potential ECUs involved and each with a different core function, specificity is all the more important. Referring to a device by it’s proper name and not a general descriptor of a secondary or, in some cases, a tertiary function facilitates good communication and helps eliminate confusion.

Another important word that’s been used in this narrative and is found in the CD program glossary is “event.” In the glossary and elsewhere10, we find “event” defined as “...a crash or other physical occurrence that causes the trigger threshold to be met or exceeded, or an air bag to be deployed, whichever occurs first...” More often, as it relates to the primary function of an ACM or ROS, it may be described as the occurrence of some level of acceleration11 which causes that ACM or ROS to evaluate available data and decide whether or not to deploy restraint device(s).

An “event” as it is used in this technology is where a trigger threshold has been met that caused the ACM or ROS to effectively “wake up” and begin running a series of logic steps which would lead to either a “decision” to deploy or not deploy a supplemental restraint (i.e.: airbags or seat belt pretensioners). This point may be referred to in the applicable literature as “algorithm enable,” “algorithm wake up” or simply “wake up.” Those terms are, in form and function, interchangeable. After that initial threshold is met and a “decision” is made, a second threshold would have to be met that initiates (triggers) the data recording function.

Figure 4: Examples of the variety of Chrysler airbag control modules.

It is entirely possible for a physical occurrence to meet the first threshold (initiating the decision making process) but, given the varied design of the ECUs under examination here, the characteristics of the occurrence (the event) may not meet that second threshold and, for that reason (among others including a vehicle-wide power loss), no data may be recorded for later retrieval using the Bosch CDR System.

The reader is encouraged to review the glossary found in the CDR program Help File for a better understanding of some of the terms which they may encounter related to this technology. Moreover, one should expect that, from timeto-time, definitions may well be updated or modified for the sake of clarity, brevity, accuracy and/or application. CDR technology is and will necessarily be evolving parallel with the capabilities and functions of the light vehicles in which we may find and recover crash data.

In the final analysis, “crash data” is that information selected as a function of the design of the ECU which may record the data relating to some physical occurrence (event) or, in the future, as a product of regulation (i.e.: 49CFR5639). To that end, since in some cases the physical occurrence which meets the trigger threshold to initiate the decision making process isn’t a “collision” but may be “just” very hard braking,3,4,12 it would be more appropriate to refer to the ECU recorded information as “event data” rather than the more limiting and situationally incorrect term “crash data.” But where is “event data” recorded?

Figure 5: This photo from a Chevrolet Suburban shows the location of the GM ROS located under the console along the center line of the car.

W

here Is “Event Data” Recorded?

The short and really meaningless answer here would be: “it’s recorded in the event data recorder (component or function).” The longer, more accurate and specific answer would be: normally within one or more specified and often related ECUs and, in those, “on” one or more Electrically Erasable Programmable ReadOnly Memory (EEPROM) chips. A EEPROM is a type of non-volatile memory commonly used in computers to store relatively small amounts of data. A “USB thumb drive” is an example of a device which would have a EEPROM as the internal component on which data may be stored.

Figure 6: The acessible Ford PCMs are in various places under the hood. This photo shows the PCM of a Crown Vic.

www.collisionpublishing.com

Collision 55

Each of the ECUs discussed thus far (i.e.: the ACM) has, as noted, a primary control function as the reason it’s even present in the vehicle in the first place. Understandably then, much of the data stored in the different ECUs will be related to that module’s primary function(s) and then any potential additional data - what might be called “external” data - may also be recorded depending on a variety of factors or considerations. Here, by original equipment manufacturer (OEM), we will explore the basics of the various modules and examine some of the potential basic data one might expect to recover from those systems.

C

hrysler Airbag Control Modules The Chrysler designation for the airbag control module (ACM) is the “Occupant Restraints Controller” (ORC).

Of course, this largely internal designation applies to Dodge and Jeep vehicles as well. Data from Chrysler vehicles became accessible starting in December 2007 (CDR v3.0).

As is the case with Ford and GM, there are several different variants of ACMs (ORCs) used by Chrysler for different vehicle applications. For example, one variant of ORCs can be used in either a Dodge Durango or a Jeep Patriot. The difference between those two modules would be seen at the software level where the module would be calibrated (in this context, meaning how it is set up or programmed) differently for each of those applications. Outwardly, those two modules would physically look alike but, internally, they would be programmed (calibrated) for different function(s) and capabilities and, one might reasonably expect, different trigger thresholds. That means the reconstructionist might anticipate that a given module calibrated for use in a larger, heavier SUV would have - among other differences - a different “wake up” threshold than might be expected for the calibration found in a smaller, lighter SUV like the Patriot.

for occupant protection. In that instance, the event would be considered a “non-deployment event” and, for certain MY10 Chryslers, data would be recorded. For Chryslers prior to MY10, the recording threshold was tied to there having been a deployment commanded and non-deployment events would not be recorded.

At the time of the release of CDR version 3.3, there were at least 5 different variants of Chrysler ORCs accessible using the CDR system.13 Each module type may record various pre-crash and crash pulse data parameters and one module type in one vehicle platform may record nominally more data than the same type of module found in a different vehicle platform (i.e.: the Durango vs Patriot comparison previously noted). In a very general sense, however, Chrysler vehicles may record data in a continuous “first in, first out” RAM memory loop of 2 or 5 seconds which is frozen at the time the module “wakes up” to the onset of the event. After that, depending on the module, it may further record as much as 250ms (0.25s) of crash pulse data relative to the vehicle’s longitudinal (X11) axis and in some cases, the lateral (Y11) axis. Depending on the module and vehicle, there may be “pre-crash” data captured in a volatile RAM memory buffer 5 or 10 times per second leading up to the point where the module “wakes up” to the event.

Some of the”pre-crash” data parameters which may be captured in RAM and then, presuming other conditions are met, recorded to the ORC’s EEPROM include: • • • • • • • •

At the time this chapter is being written, the current Bosch CDR System version is v3.4. In that version’s Help File, one finds the oldest Chrysler vehicle which is CDR System accessible is the 2005 Durango. After that, for MY06, eight more Chrysler vehicles were added as accessible and coverage (accessibility) currently extends to MY2010 Chryslers, Dodges and Jeeps (CDR ver3.3, 2009, ver3.4, 2010).

Generally speaking, for MY05-09 Chrysler line vehicles, if the ORC experiences a “physical occurrence” of sufficient projected severity such that it commands the deployment of one or more restraint system pyrotechnics - meaning airbags and/or seat belt pretensioners - the module will have also then met the recording threshold and would record data related to the “deployment event.”

Starting with MY10, some Chrysler vehicles will record data for what are known as “non-deployment events.” As the name implies, a “non-deployment event” is where the ACM has met a “wake up” threshold and, as a function of evaluating the crash conditions and sensor inputs present, “decided” that a deployment wasn’t required

Starting with MY10, some Chrysler vehicles will record data for what are known as “nondeployment” events 56 Collision

•

•

Speed, vehicle indicated Engine speed (RPM) Throttle application as a percent of 100% WOT Brake switch closures Gear shift position indicator Steering angle (measured for the steering wheel) Yaw rate Whether or not certain warning lamps were commanded “on” at the time of the crash Low tire pressure indications (as a function of a displayed and recorded warning lamp and, on certain vehicles, an indication of the actual air pressure (PSI) by tire The acceleration, in gs recorded along the one axis (normally the X axis11) and, where available, that for the Y axis11

The foregoing list is by no means all inclusive and is offered solely as a sampling of the type of data one may see stored in the Chrysler ORC in some cases where there’s been a deployment and in others where there was either a non-deployment or a deployment event.

One should refer to the Bosch CDR program Help File, the Data Limitations section of the final CDR program generated “CDR Report” and the tables found within that end report for specifics for the module under examination in a given case.

F

ord Airbag Control Modules and Powertrain Control Modules While, at this writing, recorded Chrysler crash data is found only in the Chrysler airbag control module, for some Ford vehicles, there may be data stored in more than one module on the same vehicle. When Ford systems were first accessible using the then Vetronix CDR System, access was limited to Ford airbag control modules found in MY01-03 vehicles. At that time, the MY01 Taurus and Sable and the Crown Vic line as well as the Windstar from MY01 (later through MY04) were the only accessible Ford vehicles. Other vehicles in production at the time were not initially accessible; however, Ford coverage within the Bosch CDR System has expanded dramatically since then as has the detail of the data available as coverage for many models extends back to MY01 through MY2010.

Initially, the prevailing logic at Ford - as it related to data stored in airbag control modules - was that such data would be limited to that which was related to the deployment of some component

www.collisionpublishing.com

Figure 7: A photo of a Chrysler vehicle crash test conducted by the Collision Safety Institute to evaluate the reliability of the crash data from that vehicle. of the restraint system (specifically, seat belt pretensioners and airbags). Meaning, unlike some of the data parameters listed for Chrysler (and GM) vehicles, in early CDR accessible Ford vehicles, there was simply no “pre-crash” data. That data which was available was limited to belt buckle status (buckled or unbuckled), timing of the deployment of various devices and an often very limited snapshot of crash severity (acceleration and then a cumulative, calculated delta-V).

Where Ford ACM-based data is limited to that stored in the ACM (RCM), its application in crash analysis is often limited but not because of the parameters available and lack of “pre-crash” data but rather the quantity of data that is available, particular delta-V. For example, in the MY01-04 RCM found in that model year range Ford Crown Vic, in most cases, the crash pulse acceleration data captured was limited to about 80ms (capped at 50ms after the fist pyrotechnic device was deployed). That meant that, if the goal was to deploy a device (i.e.: a seatbelt pretensioner) in about 15-50ms after the event begins, and the RCM was programmed to capture about 50ms after that device was deployed, the sum total of the crash pulse period that would be recorded would be between 65 and 100ms. Where most car-to-car crash duration is on the order of 150 to as much as 300ms, these early CDR accessible Ford modules captured a small fraction of the crash pulse data that would be most useful to a crash reconstructionist. Even as other modules became accessible in the Ford line through model year 2006, the longest crash pulse period captured was about 116ms.

Within the reconstruction community, particularly when one compared the data from the Ford systems to what was available from Chrysler or GM systems, the question was: “why so little data?” The answer was, simply, that the data wasn’t initially intended as a tool for the crash reconstructionist, the data was recorded to give Ford and the airbag control module designer some insight into what the module “saw” in and around the time of the crash and what lead to its decision - to deploy or, in some cases, not deploy - a restraint system pyrotechnic device. To that end, the ACM designer wasn’t “as interested” in the entire crash pulse was they

would be in getting a look at higher resolution data immediately leading up to then immediately after the deployment decision. For that, 100ms (or less) was usually satisfactory.

In MY05, Ford introduced a newer ACM through the Crown Vic and like vehicles which, while still only capturing raw acceleration for around a maximum of about 80ms-100ms, had a capability to capture and report delta-V for as long as the module was “working on the crash” or, more specifically, for as long as the decision making algorithm ran. For the reconstructionist, this was a huge step forward in Ford crash data and often yields a more complete “picture” of crash severity than previously observed in this vehicle line.

Still, with this approach found in the newer module, some consideration should be given to the reported algorithm run time versus a realistic crash pulse. Inasmuch as the RCM is capturing acceleration and then cumulatively calculating and then recording delta-V for as long as the decision making algorithm runs, the end user should recognize the possibility for a recorded “algorithm runtime delta-V” which may be different than one calculated for a given event as a function of a reconstruction (i.e.: a delta-V calculated from crush or based on a momentum analysis). In situations where the algorithm runtime is reported as longer than approximately 300-400ms, depending on the crash dynamics, the reconstructionist may find a delta-V based on traditional reconstruction calculated values may differ from the reported delta-V in the CDR system report14,15. (To more fully appreciate the potential impact of the algorithm runtime based delta-V relative to its reconstruction application(s), one should attend Bosch Preferred CDR Trainer CDR Analyst training or review the presentation on the disk offered with this issue of Collision from the 2010 User’s Summit as it related to algorithm run time.)

For MY07, partially in response to end user input as well as a function of seeing the “hand writing on the wall” as it related to the future implementation of 49CFR563 and in part to support the development of a more comprehensive crash safety database, Ford introduced a new line of RCMs that would not only record Continued on Page 60

www.collisionpublishing.com

Collision 57

The exclusive distributor for the Bosch CDR product line.

g n i m o C oon S

CDR Version 3.5 Hardware & Software

New CDR Chrysler Cable Release Released early 2010, the new Chrysler CDR cable is required to perform direct ACM downloads on select 2010 and newer Chrysler, Dodge & Jeep vehicles as supported in the 3.4 CDR software release and future CDR software releases.

Chrysler ACM Cable: F00K-108-516 $135.00 US | $145.75 CAN To order this cable www.cdr-system.com or (800) 280-7940

Contact CRASH DATA GROUP for ordering and special pricing information.

800-280-7940

www.cdr-system.com

ACCIDENT RECONSTRUCTION AND FORENSIC MAPPING SOLUTIONS DESKTOP MAPPING & ANIMATION SOFTWARE | EVIDENCE COLLECTION SOFTWARE & HARDWARE | TRAINING

Three desktop mapping & animation software packages to ensure your exact needs are met:

PointCloud 2010

MapScenes Forensic CAD, MapScenes Capture and MapScenes PointCloud provide professional investigators with the tools needed to visually communicate the output via accurate and compelling diagrams and animations.

Law enforcement and accident investigators use MapScenes Forensic CAD. MapScenes Forensic CAD 2010 is the most precise desktop forensic mapping software available in the world. This powerful and feature-rich application provides law enforcement professionals and accident reconstruction specialists, like you, with confidence that the evidence they present is precise, compelling, and irrefutable.

Turn the page for more information about our powerful animation and point cloud components. and MicroSurvey are Registered in the U.S. Patent and Trademark Office ® MapScenes All other brand names, product names or trademarks are property of their respective owners.

www.mapscenes.com

1.800.668.3312

ACCIDENT RECONSTRUCTION AND FORENSIC MAPPING SOLUTIONS DESKTOP MAPPING & ANIMATION SOFTWARE | EVIDENCE COLLECTION SOFTWARE & HARDWARE | TRAINING

Capture.

Animation for the real world.

Full-featured forensic animation software for creating precise and compelling 2D and 3D animations. Includes Forensic CAD 2010.

Capture gives you incredible flexibility to accurately animate your scenes - look at your data in ways you never thought possible. Our rendering capabilities give you the tools you need to analyze, edit, and build engaging animations.

Timeline and advanced object movement, animated cameras, real surfacing, vaulting and other physics tools - you will be amazed at the possibilites! and MicroSurvey are Registered in the U.S. Patent and Trademark Office ® MapScenes All other brand names, product names or trademarks are property of their respective owners.

www.mapscenes.com

1.800.668.3312

An incredible point cloud visualization tool to assist with mapping and animation.

Imagine being able to walk through a point cloud, in real-time, in order to complete your line work or conceptualize your dramatic re-creation.

With MapScenes PointCloud 2010, you can draw lines right in the point cloud viewer, which will show up in your CAD drawing. You can also include the point cloud itself in your final animation for added realism at NO extra effort. Mapping through to animating, your efficiency will soar!

PointCloud 2010

PointCloud.

Let the scene speak for itself.

1) Choose a section:

2) Draw lines:

3) You’re done!

Right on the point cloud!

and MicroSurvey are Registered in the U.S. Patent and Trademark Office ® MapScenes All other brand names, product names or trademarks are property of their respective owners.

www.mapscenes.com

1.800.668.3312

The rest of the

MapScenes System.

Evidence Collection Software:

Evidence Collection Hardware:

Certified Training:

Reduce errors, save time, and eliminate frustration.

Try these winning combinations. MapScenes Evidence Recorder is included with all hardware configurations.

When accuracy and precision are non-negotiable – fortunately, there is MapScenes.

Evidence Recorder is the world’s best selling evidence collection software built specifically for the professional reconstructionist.

Using a Windows Mobile or CE device such as the Nautiz X7, Archer or Allegro MX, Evidence Recorder allows you to experience the power, precision and productivity gains associated with being able to visually verify your ongoing field evidence collection – on-thespot, right in the palm of your hand! Then, for maximum results, it can seamlessly integrate with the MapScenes desktop software.

Nautiz X7 by Handheld exemplifies the evolution of field computers.

Packed with innovative advancements in mobile device technology, it surpasses everything else on the market with its mix of ruggedness, power and functionality.

Packages are also available for the rugged and versatile Archer and Allegro MX Field PC by Juniper Systems.

Training is essential in all facets of law enforcement. MapScenes acknowledges its responsibility to the industry by ensuring that all trainers and educational courses are kept up to date through a base educational standard, preserving quality and integrity.

We have set an industry benchmark by developing a comprehensive framework that provides investigators with the knowledge and skills required to use the MapScenes system easily, efficiently, and above all, expertly.

The MapScenes System: Evidence Collection Software Evidence Collection Hardware Desktop Mapping Software

and MicroSurvey are Registered in the U.S. Patent and Trademark Office ® MapScenes All other brand names, product names or trademarks are property of their respective owners.

www.mapscenes.com

Training

1.800.668.3312

the information related to the deployment of the airbags but also “pre-crash” data as seen in Chrysler modules. While Ford systems prior to MY07 weren’t without their usefulness in crash analysis, this newer generation of Ford RCMs brought the reconstructionist more data both in terms of more data parameters but also in the way of single module stored crash data and pre-crash data.

While initially - and until MY07 within the CDR System - Ford crash specific data was stored solely in the RCM and that data was focused solely on that which related to the function of the restraints related systems. Introduced separately in 2003, another technological development in Ford vehicles would later overlap with CDR technology in the form of “Electronic Throttle Control” (ETC).

Electronic Throttle Control is a “drive by wire” system found in late model vehicles (here limiting the discussion of the functionality to Ford vehicles starting in MY03). Prior to the introduction of ETC, the driver’s control of throttle application was by way of the accelerator pedal physically connected by a cable to the throttle body under the hood. The ETC systems disconnected that mechanical link between the pedal and throttle and gave automobile designers the ability to integrate other systems more easily (i.e.: traction and stability control).

For ETC enabled vehicles, the powertrain control module (PCM) uses sensors and electrical signals to control powertrain functions.

For example, a sensor at the accelerator pedal captures the pedal application by the driver and then translates that as an input signal to the PCM which, on the output side, uses another signal to control throttle application at the throttle body under the hood.

Where signals like these may be used by an ECU or microcomputer like the PCM, some of those signals or the result of those signals may also be stored in one fashion or another for later review. Such is the case with some of the Ford vehicles with ETC. Starting with certain MY03 Ford vehicles, and the introduction of ETC in those vehicles, between 12 seconds to slightly more than 6 minutes and 49 seconds of powertrain operational or functional data may be stored in certain (Ford) powertrain control modules.

Like the airbag control module, the PCM is not designed as an “event data recorder.” However, unlike the ACM, the PCM has no specific “event” related functionality and cannot, independently, “recognize” that the vehicle has been exposed to an “event.” Where the ACM has accelerometers designed to respond to physical occurrences (i.e.: a crash), the PCM has no such functionality in-

"

asmuch as the PCM would have no control over a system which would relate to occupant protection in an event such as a crash.

The PCM (which may also be called the VCM or Vehicle Control Module in Ford service literature) is an ECU designed to manage drive train (engine, transmission and related component) functionality. It monitors and adjusts emission related functions as well as driveability such as when the transmission moves from one gear to another or into overdrive. The specific acronym “PCM” as used to describe the powertrain control module as an ECU is often associated with the implementation of “OBD II” or “On-Board Diagnostic II” systems found in light vehicles sold since 199616. As it relates to the crash data found in light vehicles; it’s here, specifically Ford vehicles, that we find the potential for data which may be recorded in the PCM when specific conditions are met and which would then, in many instances, be “pre-crash” data although not recorded in an ACM. In vehicles where the RCM doesn’t record “pre-crash” data in that airbag control module and where that “pre-crash data” may be found separately in the PCM, there are conditions which have to be met such that the data would actually be available to the reconstructionist later for recovery using the Bosch CDR System. In a basic sense, the PCM data which may potentially become “pre crash” data for a given event is normally present and recorded in an endless loop (“circular buffer” as defined in the glossary found later in this chapter) as the car is “on” and being driven down the road; however, there is no crash related internal PCM specific function to “freeze” or “lock” that data for recovery. In essence, that means that the Ford ETC enabled PCM may continuously record - for example, for diagnostic or maintenance related recovery later in the event of a mechanical failure - powertrain related data but that data is constantly overwritten as the PCM is powered up such that, unless something else happens that “freezes” that data, after a time the stored data would cycle through and what data would be present may not relate to a specific event.

Functionally the PCM is, as described, designed to control operation of the drivetrain. In that effort, it may periodically record certain parameters that may provide for a more thorough diagnostic or other analysis of powertrain function after a mechanical failure or, in the context of the CDR System, after a crash. The currently accessible Ford PCM vehicles record up to16 parameters (data elements) associated with a common memory buffer address to maintain a time-based relationship every 0.2 seconds. Some of those parameters include:

Since the PCM was not designed to respond to or recognize a crash event, for that data to actually be available for later recovery, another condition has to be met.

64 Collision

• Speed, vehicle indicated • Accelerator pedal application (as a percentage of 100%) • Brake switch “on/off” • ABS active or inactive • Engine RPM • Speed control active or inactive • and more What all this means to the reconstructionist who can access that data is that, after it is recovered using the Bosch CDR System, PCM data would ostensibly reflect between 12 seconds and about 6 minutes 49 seconds of data in 0.2 second intervals (10 samples of each parameter per second).

However, since the PCM was not designed to respond to or recognize a crash event, for that data to actually be available for later recovery, another condition has to be met.

That condition is either (a) that the power was cut to the PCM before it began to overwrite previously stored data or (b) it received, from the RCM, what is identified as the “restraint deployment signal (RDS).” In normal operation, the PCM would, 10 times a second, take a “snapshot” of the various PCM function parameters and record them internally; in the PCM. This “snapshotting” would continue, every 0.2 seconds - even if there was a crash - unless the

www.collisionpublishing.com

Figure 8: A photo of a Ford Crown Vic crash test conducted by the Collision Safety Institute and Ontario Police College to as part of a “Level 4" course and to evaluate the reliability of the crash data from that vehicle. system lost power or received the RDS from the RCM. Lacking those conditions, if a PCM remains powered after a crash, it will continue to “snapshot” the data parameters to recorded memory overwriting the oldest recorded parameters.

This concept of the “circular buffer” is one which also describes the recording of “pre-crash” data in Chrysler ACMs (and GM ACMs), but here, seen in the Ford PCM data is a condition where, anytime an “unlocked” PCM is powered up, the PCM records data following the idea of “first in, first out.” That means that if the PCM were to record a set of data parameters about 0.2 sec after the PCM is first powered up, assuming a module capable of storing, for example, 25sec of data, it would have all but one memory address filled after 24.8sec. Then, 0.2sec later, at 25sec after being powered up, the memory buffer would be full. After that, at 25.2 seconds after being powered up, the first sample recorded (0.2sec into the sequence) would be overwritten by the data parameters observed at 25.2sec. This cycle would continue where the oldest (first recorded) data is continuously replaced by newer data over time... “first in, first out.”

If power to the PCM is lost early in a crash sequence and the PCM stops functioning, then whatever is present in the PCM’s recorded memory up to that point will remain and can be recovered using the Bosch CDR System assuming that process - as later described - is done correctly. However, if the process is not followed and the PCM powered up again, the writing process will resume and data which would have been present up to the time the power was lost (in the crash) may be overwritten.

If; however, in the sequence of events the RCM deploys a pyrotechnic restraint system controlled device (“column device,” belt pretensioners or airbags) and there is sufficient power available to the RCM to send the “restraint deployment signal” as well as sufficient power available at the PCM for it to receive that signal, then the programming of the PCM is such that it responds to that signal by “locking” the data after it records 5 more seconds worth of data. For a module that may store, for example, about 25sec worth of data, that means after recovery, the reconstructionist may have about 20 seconds of data recorded before the RDS was received and about 5 seconds of data after that time.

As one might imagine, a number of conditions may exist that might prevent the sequence from being precisely as described. For example, the PCM may receive the RDS and then, 2 seconds later loose power which would mean that, for the exemplar times noted previously, the reconstructionist would recover 23 seconds of “preRDS” data and 2 seconds of data after that point.

One aspect of this discussion; however, that cannot be omitted here is the concept of the RDS as it relates to the “moment of impact” and what the reconstructionist may perceive as an “impact speed” when reviewing PCM data. It is important to recognize that the RDS is a signal from the RCM sent after the crash begins, after the RCM makes the decision to deploy a restraint pyrotechnic and which includes, as part of that signal, a voltage drop for 0.1sec.

For that reason, the receipt of the RDS at the PCM is logically not “at impact.”

Although the current version of the Bosch CDR program may label the point where the RDS is received as “time zero,” research indicates14,15,17 that the RDS may not be received by the PCM for as much as 0.4sec or more after the onset of the collision. Inasmuch as the PCM is, at the onset of the collision, “unaware” of the crash (assuming it remains powered on), it (the PCM) would continue from that point onward recording data every 0.2sec. If it were to take, for example, 50ms (0.05sec) to deploy a restraint device and the crash pulse were to last 200ms (0.2sec) by the time the PCM receives the RDS (including a related 100ms voltage drop), the PCM may have recorded significantly lower speed(s) than was recorded when the collision itself began.

By way of example15,17, assume a Ford vehicle is moving along at 39 mph (63 km/h) and is involved in a crash (in this case a crash test, in fact, the one depicted in Figure 8). The car experiences a -15 mph (-24 km/h) delta-V (along its longitudinal axis) over 300ms (0.3sec) deploying the first pyrotechnic device at 28ms.

The PCM records the vehicle speed (“speed, vehicle indicated”) based on signals from the wheel speed sensors and calculated at the PCM based on programmed tire size and transmission information sequentially as: 38.9 mph (62.6 km/h), followed chronologically by 37.6 mph (60.5 km/h), then 24.7 mph (39.7 km/h) and then 21.5 mph (34.6 km/h). The PCM receives the RDS from the

www.collisionpublishing.com

Collision 65

RCM and records the receipt of that signal in the same memory buffer address as it records the vehicle speed of 24.7 mph (39.7 km/h).

Upon review of the data recovered from the PCM in the CDR System report, the data table reflects a “time zero” associated with the recorded vehicle speed of 24.7 mph (39.7 km/h). In the referenced example15,17, again taken from crash test data, the actual speed of the subject vehicle “at impact” was 39 mph (63 km/h) where the speed recorded at PCM time “-0.4sec” was 38.9 mph (62.6 km/h) and at PCM time “-0.2sec” it was 37.6 mph (60.5 km/h). Given the longitudinal delta-V of -15mph (-24 km/h), one can easily see that the “time zero speed” (and associated data) in the PCM report reflects a speed after impact not “at” impact (39mph -15mph = 24mph).

While it is clear from this example that the reconstructionist has to closely examine the data recovered from any CDR System accessible module in the context of a situationally complete crash reconstruction, to more fully appreciate the potential impact of RDS or lack of that RDS on PCM data and its potential use in reconstruction application(s), one should attend the Bosch Preferred CDR Trainer CDR Analyst training. A complete reading of the “Data Limitations” section of a CDR System generated report will also help the analyst better understand the data as represented.

While the Ford systems began with relatively basic data collection capabilities in MY 01 (as Bosch CDR System accessible) and progressed to more advanced systems where data would be stored in both the RCM and PCM, the latest generation Ford RCM introduced and as accessible starting with certain MY06 vehicles is one which, like its Chrysler and GM counterparts) stores crash related data as well as “pre-crash” data in the RCM itself. Some, not all, of those vehicles equipped with the newer generation RCM may “still” store additional “pre-crash” data in the PCM as well.

In the latest generation Ford RCM, data elements may include, for the period leading up to the module recognizing there has been a crash event: • • • •

Five seconds of accelerator pedal application (%) Five seconds of vehicle speed (mph) Five seconds of whether or not an ABS event in progress Five seconds of whether or not the service brake pedal was depressed

Those data elements and more are recorded at half second intervals (a sample every 0.5sec). Additionally, the modules record whether or not the seat belt(s) were buckled, presence of a passenger in the right front seat, and timing of the deployment of the restraint system controlled devices (i.e.: airbags, belt pretensioners).

The detail and applicability of the data form this latest generation of Ford RCM becomes obvious as one better understands the type(s) of data stored and contemplates its use in a situationally complete crash reconstruction. For example, information from the data recovered regarding belt use and right front occupant detection together with an evaluation of the crash PDOF, injuries to the occupants, recorded data regarding the position (on the seat track) of the driver’s seat and observations made of the condition of the driver and passenger belts might be used to help evaluate “who was driving.”

The same can be said, of course for data from other manufacturers including General Motors.

G

M Airbag Control Modules and RollOver Sensors While this chapter has discussed thus far Chrysler and Ford modules - presented alphabetically here thus far the most long-standing publically accessible light vehicle crash data is actually found in General Motors vehicles. Within the context of the Vetronix and then Bosch CDR System, GM vehicle 66 Collision

coverage begins with MY1994 and, within the latest version of that system available at this writing, carries on through MY2010.

While there is some reference in the literature to “data” in GM vehicles dating back to the “Air Cushion Restraint System (ACRS)” around MY1974, inasmuch as there were no electronic accelerometers present in those systems and no PCM-based or other “precrash” data available to record, the question might be posed, “what was recorded then?” in what is identified in GM service manuals as the “sensor/recorder” of the ACRS? The answer is: what was present after a crash was an indication of whether the timing of deployment commanded by the “sensor/ recorder” was a “high level” or “low level” event as a function of whether or not certain “electrical shorts” are discovered during a post-crash diagnostic evaluation of the system18. By way of example, a “low level” event was one where the mechanical pendulum type sensors found at the “bumper impulse detector” level and the central “sensor/recorder” were closed as a result of an impact which would then be described generally as a crash which might compare to an 11mph or greater barrier equivalent event or one which would have resulted in greater than a -18 but less than a -30g exposure for the sensors/vehicle18.

While this information might be considered a form of “crash data,” one should remember that “barrier equivalent velocity” is not equal to delta-V except under special circumstances, but they can be related mathematically if sufficient data is available19 and, by definition, cannot be the same as “impact velocity” in a car-to-car crash.

While delta-V is, of course, the change in velocity experienced by the vehicle during the impact phase of a collision, it can also refer to the total change in velocity experienced in a rigid barrier impact which may include rebound.

“Barrier Equivalent Velocity (BEV) refers to the impact velocity of a vehicle into a fixed rigid barrier that would result in the same magnitude of crush as observed on a vehicle under examination for the comparison20. In Kerkhoff 19, we find a clear objective example of the difference by way of a series of barrier then car-to-car crash tests.

In the context then of light vehicle crash data, where data is something quantitative and recorded within the EDR functionality of one or more modules in those vehicles, GM began storing meaningful data in effectively the mid-1990s. In MY95, more than 24 different GM vehicles from Saturn to Cadillac had some level of CDR System recoverable data. By MY10, we find more than 45 GM line vehicles are accessible including North American sales vehicles in the Saturn through Cadillac line and one model Holden, a Saab model and certain Suzuki and Isuzu joint-venture vehicles21.

For GM systems generally, event data is found in the Sensing Diagnostic Module (SDM): the GM designation for the ACM. While, like Ford and Chrysler, GM vehicles have a PCM, those found in GM vehicles (and Chryslers) are not a type that store data for later retrieval with the CDR System. In the earliest GM vehicles, crash data in the SDM was relatively limited. There were as few as four system status parameters reported by the earliest modules including supplemental inflatable restraint (SIR) system warning lamp (on/off), driver belt buckled/unbuckled status were supplemented by a count of the number of times the module had been powered up since it was first installed in a car. That count, known as an “ignition cycle,” was associated with either the ignition cycle count from the time the module was first powered up (normally at the factory) to the event (seen as “ignition cycles at deployment,” for example) and then later to include an ignition cycle counter to the time that the data was retrieved.

A car may be involved in a crash and airbags deployed at ignition cycle 3,114, for example, indicating that SDM had been powered up 3,114 times since, most likely the car was built. In the CDR System generated report, that would be indicated as “ignition cy-

www.collisionpublishing.com

cles at deployment.” Assuming the car was powered down after the crash and the next time it was powered up again was to retrieve the crash data, the retrieval of that data would occur on cycle 3,115 and would be reflected as “ignition cycles at investigation.”

In those earliest GM SDMs, the system status information above would be associated with a representation of delta-V, normally for a period of up to 300ms. In Ford modules, except for the most recent vintage RCMs, the RCM captured acceleration in g’s and, within the CDR System software, that acceleration together with time was used to calculate a cumulative delta-V (a related exception being the delta-V “during algorithm runtime”reported by MY05-10 Crown Vics stored separately by the RCM). In Chrysler modules, we saw that the data stored has thus far been limited to acceleration and that the end user is then responsible for making the calculation for delta-V where appropriate.

For GM vehicles, until we find the modules introduced into GM vehicles in MY10, the SDM has always recorded delta-V, not acceleration. The earliest GM modules would record up to 300ms of delta-V, calculated every 1.25ms and then averaged and recorded representing 10ms intervals of the crash pulse from the time the module recognized the onset of the event: “algorithm enable.” The SDMs that fit this description, with one exception, did not capture any “pre-crash data.”

In MY99, a new module type was introduced to GM vehicles that would capture 5 to 8 seconds - in one second intervals - of “pre crash data.” The pre-crash data was limited to 5 seconds of one sample per second each of: • • •

Vehicle speed Engine speed (RPM) Percent throttle application (measured at the throttle body)

The vehicle speed and engine speed were those values calculated by the PCM and then transmitted to the SDM for capture in the SDM’s circular “pre-crash” data buffer approximately once a second. Percent throttle was similarly transmitted to the SDM about once a second and was measured at the throttle body under the hood, not at the driver’s foot (as would be indicated in later modules as percent acceleration). Another parameter monitored, captured and recorded was the status of the brake switch as an “on or off” value. In CDR System generated reports for GM modules from the time the Vetronix CDR System was first publically available in 2001 into 2007 as the Bosch CDR System, “pre-crash data” was displayed both in a tabular format and a graph showing the “pre-crash” parameters for approximately 5 seconds “pre crash” or really, pre-algorithm enable.

End user experience, trial experience and feedback received by GM and Bosch lead to the decision to reformat the CDR System generated report and remove the “pre-crash data graph” while leaving the data table intact. Having done that, they were then free to include, in the CDR System generated report, an “additional” three seconds of “pre-crash” brake switch “on/off” indications for a total of 8 seconds of what would be then represented as “pre-crash brake switch data.” The data had been present in that retrieved from GM modules basically since “pre-crash” data was first stored in the SDMs; however, as a function of the 5 second data table and graph formatting choice, the “additional” three seconds of data wasn’t initially translated by the CDR program and, therefore, wasn’t displayed in the report until the formatting change.

Given that GM’s history in this technology pre-dates both that of Ford and Chrysler, it’s reasonable to expect that GM related CDR retrieved data has evolved or morphed more over time than that of the other two manufacturers. The idea that the “pre-crash” data was, at one time displayed in both a graph and table and then, later in only the tabular format may lead to some confusion with those not familiar with the technology as to the underlying reliability of the retrieved crash data. The important point to note here is that

the data itself - the raw numbers for, for example, vehicle speed didn’t change as a function of the report formatting change. The remaining three “pre-crash” parameters noted previously and the 5 seconds of brake switch “on/off” status remained the same, the only net effect of the formatting change was that an additional three seconds of “pre-crash” brake switch status was displayed in later reports.

Given that GM has been essentially at the leading edge of this technology since the 1990s, it stands to reason that they have encountered more anomalies and what might be described anomalies than the other OEs. A review of some of the identified and well documented anomalies makes that much fairly clear.

While no one should use a Ford, Chrysler or GM based CDR System generated data report without first reading and becoming familiar with the “Data Limitations” text found at the front of each report, the information found as part of the GM reports has the benefit of longevity, evolution and examination in testing and trial the others don’t yet enjoy. Over time, anomalies such as “data buffering,” and “reversed brake switch data” have been identified, replicated in testing and documented in Bosch Preferred Trainer CDR Analyst training as well as in the “Data Limitations” text that one finds as part of every CDR System generated report.

“Data Buffering” is the common name used to describe to a condition where, for certain modules in certain crash scenarios, the module may include in what is identified as the “pre-crash” data, a data element actually captured “post-crash.” The anomaly is described in the Data Limitations text found in the CDR System generated report for those modules which may be potentially affected by that anomaly where those certain circumstances may exist.

Similarly, a condition exists where, for a certain model year vehicle line where those vehicles are equipped with a specific engine and transmission combination, the brake switch status indication is reported backwards. In the Data Limitations text for those module/ vehicle combinations where this may, potentially, be found, the Data Limitations text reads: “If the vehicle is a 2000 - 2002 Chevrolet Cavalier Z24 or a Pontiac Sunfire GT, with a manual transmission (RPO MM5) and a 2.4L engine (RPO LD9), the Brake Switch Circuit Status data will be reported in the opposite state than what actually occurred, e.g. an actual brake switch status of “ON” will be reported as “OFF”.” “RPO” means “Regular Production Option,” a GM acronym/term for build option codes for a certain vehicle characteristics or component.

"

No one should use a Ford, Chrysler or GM based CDR System generated data report without first reading and becoming familiar with the “Data Limitations” text ...

www.collisionpublishing.com

Collision 67

Like any other identified and documented potential anomaly then, there is (1) an identified impact on the crash data (the potential anomaly) and then (2) the identified condition or characteristics of a crash or the involved vehicle that may cause the data to be effected by the potential anomaly.

A core concept in this regard, and one touched on in the Data Limitations description of the “data buffering” anomaly, is that an anomaly or characteristic present for one data element doesn’t necessarily effect others. Meaning, if a data element is effected by an anomaly, other data elements - since they are usualy dependent on other in-vehicle sources - are not effected by the anomaly or condition. An example of this is seen in this entry from the Data Limitations text for the 2000 Impala: “...Some of the Pre-Crash data may be recorded after Algorithm Enable (AE). If this occurs, it may affect the reported pre crash data values, but does not affect other data such as SDM Adjusted Algorithm Longitudinal Velocity Change...” (emphasis added).

The discussion of anomalies in this chapter might lead the uninitiated to contemplate that the CDR System retrieved data is, in some way unreliable. That conclusion would, in fact, be would be a mistake. Numerous tests14,15,17, papers, for example22,23, and the total body of the literature and documentation on the technology suggest it’s reliability and value in virtually every aspect of traffic safety.

At this writing, where the Bosch CDR system software version 3.3 is the current release, there are more than 20 different GM modules or variants of modules which can be accessed by the CDR System to retrieve data. As previously noted, the quantity and volume of data varies depending on module type, vehicle capabilities, options and characteristics and other automotive technological advances over time. There would no way within the confines of this chapter to do all the different variants and their attributes justice. To more fully appreciate the potential types of data available in GM vehicles from the SDM to the Rollover Sensor data found on certain light trucks and SUVs and its application to reconstruction, one should attend Bosch Preferred CDR Trainer CDR Analyst training and Technician training.

H

ow is the data retrieved?

As detailed in the Help file in the Bosch CDR System software and as part of the Bosch Preferred CDR Trainer Technician training, the retrieval of crash data from an ACM, PCM or ROS is a function the proper use of the CDR System for each individual application. For example, to properly access PCM data, one should be versed in the use of the CDR hardware and software to include the proper application of the PCM Adapter (Figure 9) The use of the CDR System to retrieve event data from one of the modules described in this chapter has been made, in a larger sense, relatively simple as a function of the narrowly focused operation of the Bosch CDR System. In its simplest form, the software resides on the CDR Technician’s personal computer (whether laptop or desktop) and by way of serial communication through what is known as the “CDR Interface Module” (akin to a modem), the PC communicates with one or more of the modules in which data may be recorded and the data is then copied (“imaged” as described in the CDR System program glossary) to the PC leaving the original data in the interrogated module(s).

In the CDR program Help file, the process for imaging data from one or more modules is described as a function of either an in-vehicle retrieval through the car’s wiring or a direct-to-module retrieval using a direct-to-module cable such as those seen in Figure 3.

The method of choice for retrieving event data is to connect to the module(s) while they’re still in the car. As seen in Figure 10, the CDR System is designed to enable the Technician’s PC to communicate with the modules in which there may be data by way of the car’s wiring. Connecting through the DLC (also identified as the “OBD II port”), the technician uses the car’s wiring and (where possible) power to retrieve data form the module without disturbing it in the car.

In the alternative and where a retrieval through the car’s wiring isn’t possible, a direct-to-module retrieval - preferably while the module remains bolted down in the car - may be attempted as seen in Figure 11.

Within the Bosch CDR System Help file, there is a discussion of the preferred method of access and potential for removal of the module from the vehicle for a direct-to-module retrieval. That section reads:

R

emoving a Module from a Vehicle The recommended practice as recommended by the automobile manufacturers whose vehicles are accessible by the CDR system and Bosch is to avoid removing the module for data collection whenever reasonably possible. Below are some guidelines that may help in facilitating this practice: Always attempt data collection through the vehicle’s DLC connector first provided the condition of the vehicle’s electrical system can support this. Make all reasonable efforts to safely restore the electrical system so that data collection can be enabled through the DLC. If collection of data through the DLC connector is not possible, then the user should attempt to collect data from the module directly with the module remaining installed in the vehicle using the specified ‘direct-to-module’ cable or cable & adaptor. When connecting the ‘direct-to-module’ cable to the module, remove only the vehicle harness connector(s) from the module that is (are) necessary to plug in the specified CDR cable, leaving other harnesses connected during the data collection.

Figure 9: As a component of the Bosch CDR System , the PCM adapter is required to retrieve PCM based event related data.

68 Collision

If either of the options above is not reasonably possible or the user wishes to retain the module pending potential support in a future release of the CDR tool then the final option may be to remove the module from the vehicle for data collection by the CDR system at the user's own risk.

www.collisionpublishing.com

Figure 10: Depicts the setup for an in-car download.

Figure 11: Depicts the setup for a direct-to-module download. www.collisionpublishing.com

Collision 69

Removal of a module from a vehicle may lead to the data in that module being changed or overwritten. These instructions describe the preferred practice and may be in conflict with a local policy or direction from competent and informed legal authority. Neither Bosch nor the automobile manufacturers whose vehicles are accessible using the CDR system assume any liability or other responsibility for removal of a module. If you choose to remove the module, always refer to the appropriate service information for air bag control module removal instructions before proceeding.24” The modules are, within the limits of the condition of the subject vehicle after a collision, found in various locations within the vehicle, often as described in the CDR System Help file. The previously described position of the ROS as seen in Figure 5 or the PCM as seen in Figure 5 as well as the example locations of the airbag control modules depicted in Figures 12, 13 and 14. For a complete understanding of how data may be retrieved from a supported vehicle one should attend Bosch Preferred CDR Trainer CDR Analyst training and Technician training such as that offered by the Northwestern University Center for Public Safety.

L

itigation and Admissibility Event data found in passenger cars, light trucks and SUVs represents a huge step forward in terms of more thorough, detailed and reliable analysis of crashes toward improving traffic safety. As with any related technology, CDR technology has found its way into litigation - both civil and criminal.

Narrowly on the subject of the CDR Technology there have been several notable cases where CDR System retrieved data was challenged but ultimately admitted at trial. In many cases the chal-

Figure 12: A “center tunnel” module mounting location from a 2007 model Ford vehicle 70 Collision

lenge was made in “Daubert25” or “Frye26” type hearings. Recognizing that the “Daubert”- type admissibility is, of course, applied individually by the courts in some, but not all jurisdictions27, these typical guideline tests and may be applied by the courts before admission of the CDR System retrieved data: 1. The extent to which the theory has been or can be tested Apart from the conduct numerous crash tests where evaluation of CDR System gathered data was one of the or the specific foci of the tests, bolth individuals and organizations including government and industry throughout the US and Canada have tested the underlying in-vehicle components and systems as well as the use of and translation effectiveness of the CDR System. The references found in this chapter are clearly not all-inclusive of the body of the literature available on the topic.

2. The extent to which the technique relies upon the subjective interpretation of the expert The function of the CDR System to complete the basic translation of the data recorded in a given vehicle requires no user/expert intervention or interpretation. The output report created by the CDR System requires no direct analyst interpretation or intervention.

The analyst expert would be required to associate the output data with an event under study and to identify known anomalies where appropriate (see also item 4 below) - a specific skill set developed as a function of particular training and experience in crash analysis (reconstruction) and then training with respect to the CDR System itself.

Figure 13: A “center tunnel” module mounting location from a 2004 model GM vehicle -

www.collisionpublishing.com

Figure 13: A “center tunnel” mounting location from a 2008 model Chrysler vehicle 3. Whether the theory has been subjected to peer review and/ or publication The notion here of a “theory” needs definition. There is no “theory” involved in what may be described as “CDR technology” inasmuch as the components are long adopted, long used mechanical and/or electronic systems found in passenger cars, light trucks, and SUVs for many years. As illustrated in testimony found in, for example, “Bachman28” or “Zimmerman29” there is no new or novel “theory” rather, CDR retrieved data is simply information stored in long adopted and long used technologies found within the automotive industry and, beyond that, in other common applications.

With respect to peer review and/or publication, compiling a single “authoritative list” of publications - from whatever source - would be virtually impossible given that one would have to first define which of the many involved component(s) may be of interest as the subject of that list and then it would require the assembly of the many documents relating to those various components, their function and evolution over time as well as the related functions and components including those within the airbag control module (PCM or ROS) at various levels. Or, is the anticipated area of inquiry the function of the CDR System? Again an area with a lengthy document history. In either case, defining the component and then the specific and/or related documents, studies and papers is, at a minimum, a daunting task simply because there are so many such long standing systems.

For example, the National Highway Traffic Safety Administration (NHTSA) EDR30 web site lists a wide ranging bibliography31 of more than 150 articles and papers dating from 1953 through 2005 but even that list does not include the more recent and narrowly focused NTSB/SAE Symposia on Event Data Recorder (EDR) Technology held in 2004 and again in 2007 among many other potential references similarly excluded since little of that list relates to components external to the airbag control function or system.

4. The technique's potential rate of error If the “technique” is defined as “the means by which results (conclusions of the analysis) to be offered as evidence has been obtained,” the topic is easy to address. The basic “technique” employed by the analyst is (1) to establish that the data came from the event under study, (2) evaluate the potential for anomalies that may impact the data, then (3) compare the data to the event under study for its value and assistance in understanding the event. That methodology, that analyst-specific “technique” requires no extraordinary steps which would be beyond the scope of a trained and experienced crash analyst who has also been trained in the use of the CDR System.

If one assumes the definition of “technique” is an evaluation of the function of the various related components found in the vehicle, this test is again easy to meet. Each of the individual mechanical or electronic components related to the airbag system or CDR System have identified rates or potential for error or anomaly and are all long used and long adopted in their individual roles and applications.

For example, a potential “offender’s” car’s speed based on the visual observation of a patrol car’s speedometer during a police “pace” of that speeding driver and then orally reported by a police officer has long been recognized as admissible. That “technique” relies on the officer’s observation of a match in speed between the two vehicles, his observation of the speedometer reported speed, an estimation of duration time or distance for that “pace” and his personal integrity at trial when reporting that observed speed - all of which rely on the notion that the speedometer was able to reasonably accurately report the patrol car’s speed in the first place. Ultimately, the one independent, objective component - the source of that speed at the patrol car level - has the very same source as is found in the CDR System generated report as it relates to vehicle speed. However, instead of it being orally reported, as it relates to the CDR System

www.collisionpublishing.com

Collision 71

generated report data, it is the result of the recording of multiple, individual, independent samples, each with its own electronic validity code, which, at the end of the day, are recorded in a long accepted method for later reporting, objectively and without the need for an intervening human involvement or other “technique.”

5. Whether the underlying theory or technique has been generally accepted as valid by the relevant scientific community As it relates to this technology, one should have to first define the “relevant community.” That being said, whether that identified community is the auto manufacturers, government, crash researchers, or police agencies virtually anyone with demonstrable familiarity with the technology has not only generally, but in most cases, specifically accepted it as valid, reliable and relevant. On the one hand, government agencies in both the US and Canada rely on the data recovered using the CDR System for regulatory and general safety purposes. It is, for example, the very subject of a specific portion of Title 49, Code of Federal Regulations, Part 563 (49CFR563 5). The data has been used to support design changes and even vehicle recalls. Police agencies and private crash analysts routinely use the data in criminal and civil litigation. Crash researchers use the data to further research and advance various safety projects throughout North America and indeed in other countries.

There is a growing history of the admissibility of CDR System retrieved data being analyzed in the context of a situationally complete crash analysis and ultimately admitted at trial in courts throughout the US32 and Canada.

S

ummary The use of CDR System retrieved data since 2000 has demonstrably expanded the traffic safety knowledge base generally and has clearly become a useful and valuable tool for crash reconstructionists. With future developments such as the pending implementation of 49CFR5635, and technological advances within automotive technology, it’s clear that this evolving and expanding area of crash analysis is one a well rounded crash reconstructionist should work to stay abreast of. This chapter is offered as an overview, a snapshot of the technology limited to the state of the art at this writing and the contents are subject to changes in vehicle systems, data recording capabilities and the evolution of the CDR System generally.

R

eferences 1. Chidester, Augustus "Chip," et al, “Recording Automotive Crash Event Data,” International Symposium on Transportation Recorders, 1999

2. Vetronix Corp, “Vetronix Corp. Launches the Automotive Crash Data Retrieval System,” press release through Business Wire and Automotive Wire, March 13, 2000 3. Haight, W. R., “Automobile Event Data Recorder (EDR) Technology - Evolution, Data, and Reliability,” The Institute of traffic Accident Investigators, 5th International Conference, York, UK, 2001 4. Floyd, Don, W. R. Haight, Bruce Turner and James Kerr, “Vetronix Crash Data Retrieval (CDR) Training Seminar,” Vetronix Corp, General Motors and The Collision Safety Institute, June 2001 5. 49CFR563.3, “Part 563 - Event Data Recorders, Application” 6. “‘Black boxes’ will aid in auto collision injury analysis,” Insure. com; last updated 8/2004, last accessed September 9, 2009, http:// www.insure.com/car-insurance/event-data-recorder.html 7. Haight, W. R.; “Data Recorders - the “Black Box” and Supplemental Restraint Systems,” Texas Engineering Extension Service (TEEX), Texas A&M University System, 2000 72 Collision

8. Vetronix Corp, “Select Ford Vehicles Now Supported in Vetronix’s New Crash Data Retrieval Software,” press release through Business Wire and Automotive Wire, March 11, 2003 9. Zate, Maria; “German Auto-Parts Giant Bosch Buys Santa Barbara, Calif.-Based Vetronix,” Santa Barbara News-Press, August 27, 2003 10. 49CFR563.5, “Part 563 - Event Data Recorders, Definitions” 11. Note here that “acceleration” is used to describe the vector quantity for the rate of change of velocity. Its polarity - positive or negative - relative to a linear axis in a light vehicle is defined in SAE J211, SAE J760 and SAE J1733.

12. Chan, Ching-Yao, "Fundamentals of Crash Sensing in Automotive Air Bag Systems," The Society of Automotive Engineers, 2000 13. Robert Bosch GmbH; “Crash Data Retrieval System Help File,” as found under the heading “Collecting Data” and then the subheading “Supported Chrysler Vehicles” one may see the list of accessible vehicles by year, make and model. Each is associated with a direct-to-module cable. In this document, there are 5 different direct-to-module cables listed suggesting at least 5 different modules may be found in the various Chrysler vehicles.

The current version of the CDR System referenced is version 3.3, released September 2009.

14. Haight, W. R., Brad Muir; “Crash Conference Crash Data Review, ARC-CSI Crash Conference 2009,” ARC-CSI, Las Vegas, NV, 2009 15. Haight, W. R. , Brad Muir; “Crash Test Data Review, Level 4 Course,” Ontario Police College (Aylmer, Ontario, Canada), Collision Safety Institute and the Ontario Police College, 2009 16. 40CFR86.094; see also CCR Title 13, Section 1968, California Air Resources Board (CARB) 17. Muir, Brad; “Ford PCM Data Applications;” Proceedings of the 25th Anniversary National Conference and AGM,” The Canadian Association of Technical Accident Investigators and Reconstructionists, 2009 18. Cooley, Peter; “A Manual for Evaluating the Performance of the Electrical Circuitry of the General Motors Air Cushion restraint System;” Highway Safety Research Institute, University of Michigan, 1977 19. Kerkhoff, John F., et al; “An Investigation into Vehicle Frontal Impact Stiffness, BEV and Repeated Testing for Reconstruction;” Society of Automotive Engineers, #930899. 1993 20. Hight, Phillip V., et al, “Barrier Equivalent Velocity, Delta-V and Crash3 Stiffness in Automobile Collisions,” Society of Automotive Engineers, #850437, 1985 21. Robert Bosch GmbH; “Crash Data Retrieval System Help File,” as found under the heading “Collecting Data” and then the subheading “Supported GM Vehicles” one may see the list of accessible vehicles by year, make and model. The current version of the CDR System referenced is version 3.3, released September 2009.

22. Lawrence, Jonathan M., et al; “The Accuracy of Pre-Crash Speed Captured by Event Data Recorders,” MacInnis Engineering Associates, Society of Automotive Engineers, #2003-01-0889 23. Wilkinson, Craig C., et al; “The Accuracy of General Motors Event Data Recorders in NHTSA Crash Tests”; MEA Forensic Engineers & Scientists, Proceedings of the CDR User’s Conference, 2007

www.collisionpublishing.com

24. Robert Bosch GmbH; “Crash Data Retrieval System Help File,” as found under the heading “Collecting Data” and then the subheading “Removing a Module from a Vehicle.” The current version of the CDR System referenced is version 3.3, released September 2009.

Bachman, et al, v. General Motors Corp., Uftring ChevroletOldsmobile, Delphi Automotive Systems and Delco Electronics Systems, Illinois App. Ct., 4th Dist., No. 4-01-0237, and appealfrom Woodford County Circuit Court, Case No. 98L21 (2002)

25. Daubert v. Merrell Dow Pharmaceuticals, Inc., 43 F.3d 1311 (9th Cir. 1995).

Arizona v. O'Brien, Superior Court of Arizona, Maricopa County, Case No. Cr 2003-016197-001 DT (2004)

26. Frye v. U.S., 293 F.1013 (D.C. Cir. 1923)

California v. Sanchez, Ventura County Superior Court, Case No. 2001 9000 34 (2003)

27. Bohan, Thomas L., Joseph A. Keierleber,“Ten Years After Daubert: The Status of the States,” delivered by JAK, February 2004 at the 56th Annual Meeting of the AAFS, Dallas, TX. 28. Bachman, et al, v. General Motors Corp., Uftring ChevroletOldsmobile, Delphi Automotive Systems and Delco Electronics Systems, Illinois App. Ct., 4th Dist., No. 4-01-0237, and appealfrom Woodford County Circuit Court, Case No. 98L21 (2002) 29. Commonwealth of Massachusetts vs. Michelle M. Zimmerman, Ipswich Division of the District Court, No. 06-P-1240 30. Event Data Recorder - Here used to describe a function within a module which has the capability to save certain crash parameters after primary functions are completed. It may record a vehicle’s dynamic, time-series data during and/or just prior to a crash event intended for retrieval after the crash event 31. See http://www-nrd.nhtsa.dot.gov/edr-site/bibliography.html 32. Example cases where CDR technology has been admitted include: Commonwealth of Massachusetts vs. Michelle M. Zimmerman, Ipswich Division of the District Court, No. 06-P-1240

California v. French, 3rd Cal. App. Dist. Ct., (unpublished) (2003) Michigan v. Wood, 56th Circuit Court, Case No. 02-283-FH (2003) Michigan v. Schubert, 13th Circuit Court, Case No. 04-9625-FH (2005) New Jersey v. Shabazz, Union County Superior Court, Case No. 05-03-00372-I (2005) New York v. Hopkins, Monroe County Court, Case No. 20040338 (2004) People v. Slade (and Slocup), 233 N.Y.L.J. 11, Nassau County Superior Court (2005) Texas v. Zachary, 24th Judicial District Court, Case No. 36975 (2006) Johnson v. Hairrston, et al, 21st Judicial District, Henry County Circuit Court, Case No. CL 05-063 (2007)

Editor's note: This article is an expansion of the basic, historical information found in Chapter 19 of "Traffic Crash Reconstruction" by Lynn Fricke as published by the Center for Public Safety, Northwestern University. the author here, Rusty Haight together with co-authors Thomas Green and Mike DiTallo developed the larger treatment of this topic as seen in Chapter 19 in this, the latest edition of the manual. Go to http://nucps.northwestern.edu/cart/cart_item_detail.asp?id=302 for information on how to get this most recent comprehensive reconstruction manual.

www.collisionpublishing.com

Collision 73

Back to Table of Contents

I

ntroduction Accident reconstructionists have typically assumed that, when a vehicle rolls over, it decelerates at a constant rate. While this is not actually the case, this assumption has been adequate for the purpose of determining the speed at which a vehicle began rolling over. In the last decade, however, the drive to develop more sophisticated occupant protection systems has compelled safety researchers to a greater interest in detailed analysis of a rolling vehicle’s motion. For example, analysts have started to contemplate the severity of the particular vehicle-to-ground impacts that occur when a vehicle rolls over and to identify the specific conditions under which occupants in a rolling vehicle are ejected. When such considerations arise, the translational and angular velocity conditions of the rolling vehicle 74 Collision

along the entire roll path take on much greater significance.1 In a recent paper, Carter demonstrated that significant inaccuracies resulted when a constant deceleration rate was used to determine the mid-stream velocity conditions of a rolling vehicle.2 Carter used a constant deceleration rate to analyze two rollover crash tests and found that this approach overestimated the ve-

www.collisionpublishing.com

A Variable Deceleration Rate Approach to Nathan A. Rose Gray Beauchamp Kineticorp, LLC

www.collisionpublishing.com

Collision 75

hicles’ translational, or over-the-ground (OTG), speeds at most discrete points along the roll distances. Further, he found that using a constant deceleration rate resulted in the peak roll velocities being overestimated and the duration of the rollover being underestimated.

In Figure 1, the vehicle’s deceleration rate at the beginning of the roll phase is represented with the symbol f0 and its deceleration rate at the end of the roll phase with the symbol ff. The roll distance is given with the symbol droll and di is an arbitrary distance along the roll path.

To remedy the inadequacies of the constant deceleration rate approach Carter proposed using a variable deceleration rate approach to rollover reconstruction in which one would divide the roll phase up into a sequence of discrete contacts with the ground and assign a deceleration rate to each of these impacts. In this approach, the vehicle would maintain a constant speed during its periods of airborne motion. Carter did not, however, present any methodology for determining the deceleration rate of the vehicle during the vehicle-to-ground impacts. Rose and Beauchamp termed Carter’s approach the discrete events approach and worked to develop it using analytical modeling and simulation.3,4,5 This research by Rose and Beauchamp demonstrated that, given physical evidence sufficient to identify each of the discrete impacts, a discrete events approach could be successful. That said, this approach was time-consuming to the point of being impractical and it was fraught with potential sources of error.

Rose and Beauchamp proposed an alternative termed the discrete regions approach. In this simpler approach, one would not need to parse out and identify each discrete impact that occurred during the rollover (although one might have other reasons for doing so). Instead, in this approach, one would vary the deceleration rate in a series of regions, with the dividing lines between regions being defined by characteristics of the vehicle’s roll velocity history.

The simplest manifestation of the discrete regions approach would be to use a mathematical function to smoothly vary the deceleration rate over the course of the roll distance. Rose and Beauchamp demonstrated theoretically that the deceleration rate exhibited by a rolling vehicle will generally decrease over the course of the roll distance (when the vehicle is rolling on a single surface).6,7 Based on this trend, they also demonstrated that a using a linearly decreasing deceleration rate across the roll distance produced more accurate translational and angular velocity time histories than using a constant deceleration rate.

Figure 1 Given the linearly decreasing characteristic of the deceleration rate shown in Figure 1, the average deceleration rate of the vehicle over the roll distance, favg, is given by Equation (1). The slope of the deceleration versus distance curve, m, would be given by Equation (2).

(1)

The present article further develops this second variable deceleration rate approach to rollover crash reconstruction. It begins by developing a set of equations for applying a variable deceleration rate approach using a linearly decreasing deceleration rate. In presenting these equations, this article aims at helping the reader to envision, in a step-by-step fashion, how a variable deceleration rate approach to rollover reconstruction could be implemented.

In conjunction with developing these equations, analytical uncertainty analysis techniques are employed to explore the manner in which uncertainties will propagate to the calculated vehicle velocity histories. Next, the paper applies these equations to analyze two rollover crash tests and demonstrates again that even a simple variable deceleration rate approach yields results superior to a constant deceleration rate approach.

Equations (1) and (2) can be combined so that the slope of the deceleration rate curve is given in terms of the initial and average deceleration rates by Equation (3).

V

Thus, the instantaneous deceleration rate at any position along the roll distance, fd, is given by Equation (4).

ariable Deceleration Rate Approach During a rollover, a vehicle decelerates when it is in contact with the ground and maintains a generally constant velocity when it is airborne. However, it will most often be impractical to conduct sufficient analysis of a rolling vehicle’s motion to assign an accurate deceleration rate to each individual ground impact experienced by the vehicle. Thus, in attempting to improve upon the traditional assumption that a rolling vehicle decelerates at a constant rate, it seems best to develop an approach that captures general trends in the way the deceleration rate varies across the roll distance but does not require a detailed reconstruction of each individual ground impact. To develop such an approach, this article uses a deceleration rate that decreases linearly across the roll distance.

76 Collision

(2)

(3)

(4) The deceleration rate of the vehicle can be related to the vehicle’s OTG speed with Equation (5). In this equation, ad is the vehicle’s instantaneous deceleration rate at an arbitrary distance along the roll path, fd is this same deceleration rate expressed in gravitational units, g is the gravitational constant, vd is the vehicle’s OTG veloc-

www.collisionpublishing.com

ity at the arbitrary roll path distance, and the variable t denotes time.

(5)

U

ncertainty Analysis Equations To quantify the uncertainty associated with the equations of the previous section, begin by assuming that the total roll distance, droll, and the instantaneous position of the vehicle along the roll distance, di, are known with certainty from consideration of physical evidence. The maximum uncertainty in the instantaneous OTG speed can be then calculated with the following equation:

Equation (5) can be integrated as shown in Equation (6). The left side of this equation is integrated from an intermediate roll position, di, to the end of the roll phase, droll, and the right side is integrated from the vehicle’s OTG speed at the intermediate roll position to rest.

(12) Evaluating the partial derivatives of Equation (12) yields the following expression:

(6) This integration yields Equation (7), which relates the vehicle’s OTG speed at any point along the roll path to the initial and average deceleration rates, the vehicle’s position along the roll path, and the total roll distance. These inputs are identical to those used in the constant acceleration approach, with the exception that an initial deceleration rate must be specified.

(7) An analogous expression for a constant deceleration rate approach would be written as follows:

(13) An analogous uncertainty equation for a constant deceleration rate approach is given by Equation (14).

(14) The maximum uncertainty in the average OTG speed between two positions along the roll path is given by the following equation:

(8)

(15)

To quantify the time that elapses between any two positions on along the roll path, d1 and d2, the vehicle’s average velocity between those points needs to be calculated. For our purposes here, it will be sufficient to estimate the average velocity between two positions with Equation (9):8

Equation (16) will yield the maximum uncertainty in the time that elapses between two positions along the roll path.

(9)

(16)

The time that elapses between these positions can then be obtained with the following equation:

And finally, Equation (17) will yield the maximum uncertainty in the average roll velocity between two positions along the roll path.

(10) Once this time is obtained, the following expression will yield the vehicle’s average roll velocity between the vehicle positions at d1 and d2:

(11) In this equation, θroll,1 and θroll,2 are the vehicle roll angles at positions 1 and 2, respectively.

(17) Equations (13) and (17) were used to assess the uncertainties arising in the analysis reported later in this paper.

C

omparison with Crash Test Data To determine the degree to which using a variable deceleration rate approach would be expected to improve the accuracy of rollover reconstruction, the authors used the linearly decreasing deceleration rate approach described in the previous sections to analyze two rollover crash tests. For comparison, we also analyzed these tests with a constant deceleration rate

www.collisionpublishing.com

Collision 77

approach. These crash tests were originally reported by Luepke.9 Then, analysis of these tests with a constant deceleration rate approach was reported by Carter10 and with various variable deceleration rate profiles by Rose and Beauchamp.11 This previous analysis sought a best fit between the crash test data and the results of the various variable deceleration rate approaches. The analysis reported here extends this previous analysis of these tests by employing techniques of uncertainty analysis in conjunction with a variable deceleration rate approach to demonstrate, in practice, the degree to which the variable deceleration rate approach would improve the results of a reconstruction.

"

Rollover crash reconstruction has historically utilized an average deceleration rate for the entire roll phase and so the literature contains quite a bit of average decelerate rate data.13,14,15,16,17,18,19 Generally speaking, reported average deceleration rates have fallen in the range of 0.4 to 0.6g, though the literature contains values as low as 0.34 and as high as 0.65g. Recent literature has also begun to explore the deceleration rate at specific points along the roll distance, including early in the roll. This data is helpful for beginning to

During a rollover, a vehicle decelerates when it is in contact with the ground and maintains a generally constant velocity when it is airborne.

Both of the tests considered here were dolly rollover crash tests conducted at the Exponent Test and Engineering Center in Phoenix, Arizona in a manner similar to that specified in the Society of Automotive Engineers Recommended Practice J2114. This test procedure involves generating a lateral roll of the test vehicle by accelerating a dolly, on which the vehicle sits, up to the test speed, then decelerating that cart at a sufficient rate to initiate the rollover.

The vehicle is situated on the cart perpendicular to the initial velocity direction with an initial roll angle of 23 degrees. In the tests under consideration here, the vehicles were situated on the dolly with their driver’s sides leading. The vehicles were launched onto a 6” layer of lightlycompacted desert soil.

In the first test, which was run with a 1998 Ford Expedition, the test vehicle was launched at a speed of 43.2 mph. The vehicle rolled 4 times in approximately 120 feet, having an average deceleration rate over this distance of 0.52 g. The distance from the position at which the vehicle first touched down coming off of the dolly to the time the vehicle came to rest was approximately 113 feet, and over this distance, the vehicle had an average deceleration rate of 0.55g.

In the second test, which was run with a 2004 Volvo XC90, the test vehicle was launched at a speed of 42.9 mph. The vehicle rolled 4-¼ times in approximately 115 feet, having an average deceleration rate over this distance of approximately 0.53 g. The distance from the time the vehicle first touched down coming off of the dolly to the time the vehicle came to rest was approximately 111.5 feet, and over this distance, the vehicle had an average deceleration rate of 0.55g.

Carter conducted a frame-by-frame analysis of the video footage of these tests and correlated the vehicle positions and orientations to the physical evidence deposited on the test surface.12 Based on the spatial and temporal positions of the vehicles in these tests, Carter calculated OTG speed versus time curves for each of the tests. He also obtained roll velocity histories for these tests from sensor data. In conducting our analysis for this paper, we relied on Carter’s prior analysis, utilizing his vehicle positions and orientations and his OTG speed and roll velocity versus time plots as the actual values which any approach to rollover reconstruction would strive to match.

78 Collision

"

define a range of initial deceleration rates that could be employed in the variable deceleration rate approach described in this paper.

Gee, et al., analyzed a real-world rollover that was captured on video and found that the average deceleration rate early in the rollover was between 0.5 and 0.6.20 Since these represent averaged values, they are likely low compared to the actual initial deceleration rate.

In previous analysis of the two dolly rollovers analyzed in this article, Rose and Beauchamp found that using initial deceleration rates around 0.8 resulted in an excellent match with the OTG speed curves for the Expedition and Volvo dolly rollover tests. Considering this data, in this article, we utilized average deceleration rates between 0.4 and 0.6g for both the constant and variable deceleration rate approaches and an initial deceleration rate between 0.6 and 0.8 for the variable deceleration rate approach.

Figure 2 consists of two graphs. In each of these graphs, time is plotted on the horizontal axis and OTG speed on the vertical axis.

The graph on the left depicts OTG speed versus time plots for the Expedition test, calculated with constant deceleration rates of 0.4 and 0.6. For comparison, this graph also depicts the actual OTG speed versus time curve. The graph on the right depicts OTG speed versus time plot for the Expedition test, this time calculated with linearly decreasing deceleration rates beginning at 0.6 and 0.8, and decreasing with a slope that would yield average deceleration rates of 0.4 and 0.6. Again, this graph contains the actual OTG speed versus time plot for the test.

Comparison of these two graphs yields the following observations: (1) both the constant and variable deceleration rate approaches yield a range of initial speeds that encompass the actual initial speed; (2) the range of speed-time histories that the constant deceleration rate approach yields fail to capture the actual speed-time

www.collisionpublishing.com

Figure 2

Figure 3 history for much of the roll duration, overestimating the speed over much of the first half of the rollover and underestimating the speed during the later portions of the rollover; (3) the range of speedtime histories that the variable deceleration rate approach yields encompasses the actual speed-time history for most of the first half of the roll and underestimates the speed during the latter half of the roll to less of a degree than the constant deceleration rate approach; (4) the range of rollover durations calculated with the variable deceleration rate approach encompasses the actual event duration, whereas, the range of durations calculated with the constant deceleration rate approach underestimates the actual event duration.

Figure 4 consists of two graphs. In each of these graphs, time is plotted on the horizontal axis and OTG speed on the vertical axis.

The graph on the left depicts OTG speed versus time plots for the Volvo test, calculated with constant deceleration rates of 0.4 and 0.6. For comparison, this graph also depicts the actual OTG speed versus time curve. The graph on the right depicts OTG speed versus time plot for the Volvo test, this time calculated with linearly decreasing deceleration rates beginning at 0.6 and 0.8, and decreasing with a slope that would yield average deceleration rates of 0.4 and 0.6. Again, this graph contains the actual OTG speed versus time plot for the test.

Figure 3 consists of two similar graphs containing roll velocity versus time plots. Again, the graph on the left utilized a constant deceleration rate approach and the graph on the right utilized a linearly decreasing decelerate approach. For comparison, each of these graphs also contains the actual roll velocity time history for the test. Comparison of these two graphs yields the following observations: (1) the constant deceleration rate approach yields a range of peak roll velocities that overestimate the actual peak roll velocity; (2) the variable deceleration rate approach yields a range of peak roll velocities that encompass the actual peak roll velocity; (3) both approaches reasonably predict the timing of the peak roll velocity; (4) the range encompassed by the roll velocity curves generated with the constant deceleration rate approach rarely encompass the actual roll velocity curve; (5) the variable deceleration rate approach yields roll velocity curves that are reasonably close to the actual roll velocity-time history; (6) both approaches underestimate the roll velocities during the last second of the rollover, but the variable deceleration rate approach to a lesser degree than the constant deceleration rate approach.

Comparison of these two graphs yields the following observations, similar to those for the Expedition test: (1) both the constant and variable deceleration rate approaches yield a range of initial speeds that encompass the actual initial speed; (2) the range of speedtime histories that the constant deceleration rate approach yields fail to capture the actual speed-time history for much of the roll duration, overestimating the speed over the middle third of the rollover and underestimating the speed during the later third of the rollover; (3) the range of speed-time histories produced by the variable deceleration rate approach represent a clear improvement over those produced with the constant deceleration rate in terms of their agreement with the actual speed-time history; (4) again, the range of rollover durations calculated with the variable deceleration rate approach encompasses the actual event duration, whereas, the range of durations calculated with the constant deceleration rate approach underestimates the actual event duration.

Figure 5 consists of two similar graphs containing roll velocity versus time plots for the Volvo test. Again, the graph on the left

www.collisionpublishing.com

Collision 79

Figure 4

"

Figure 5

... using a linearly decreasing deceleration rate approach to rollover reconstruction reduces the error in the reconstructed translational and angular velocity-time histories.

80 Collision

utilized a constant deceleration rate approach and the graph on the right utilized a linearly decreasing decelerate approach. For comparison, each of these graphs also contains the actual roll velocity time history for the test. Comparison of these two graphs yields the following observations, similar to those for the Expedition test: (1) the constant deceleration rate approach yields a range of peak roll velocities that overestimate the actual peak roll velocity; (2) the variable deceleration rate approach yields a range of peak roll velocities the encompass the actual peak roll velocity; (3) both approaches reasonably predict the timing of the peak roll velocity; (4) the range encompassed by the roll velocity curves generated with the constant deceleration rate approach rarely encompass the actual roll velocity curve; (5) the variable deceleration rate approach yields roll velocity curves that are reasonably close to the actual roll velocity-time history; (6) both approaches underestimate the roll velocities during the last one to two seconds of the rollover. (7) Overall, the variable deceleration rate approach yields roll velocity curves that are closest to the actual roll velocity-time history for the test.

D

iscussion The data and analysis presented in the previous section confirm that using a linearly decreasing deceleration rate approach to rollover reconstruction reduces the error in the reconstructed translational and angular velocity-time

www.collisionpublishing.com

histories. Thus, implementing such an approach would also reduce the errors that could arise, first, when analyzing the severity of a particular vehicle-to-ground impact or, second, when analyzing occupant ejection scenarios.21,22 A number of topics remain to be explored within this approach.

First, the literature could benefit from more examination of how exactly the deceleration rate of the vehicle varies over the course of a rollover. It may be that there would be a better functional shape than a line to model the variability of the deceleration rate across the roll path. The high-speed rollover tests that Asay and Woolley have recently added to the literature – tests in which the rollovers were initiated under very realistic conditions – hold considerable promise for illuminating this and many other issues.23,24,25 Second, it remains unclear the degree to which the rollover surface (e.g., asphalt, dirt, grass, gravel, etc.) affects the deceleration rate.

Our previous publications have shown theoretically that there may be such dependence and some empirical data seems consistent with this conclusion. Still, there are confounding factors (vehicle shape and speed, for instance) and separating the effects of surface from the effects of these other variables seems a daunting task with the currently available data. If a rolling vehicle’s deceleration rate is dependent on the surface type, then the procedure outlined in this article may need revised when a vehicle rolls across multiple surfaces. This is an issue that deserves further research as new rollover test data is added to the literature.

Finally, a variable deceleration rate approach like the one detailed in this article could benefit from more extensive validation. Again, the data being generated by Asay may provide the means to accomplish this additional validation.

The need for further research acknowledged, the variable deceleration rate approach to rollover reconstruction is a more physically realistic approach than a constant deceleration rate approach.

Multiple articles have demonstrated the improvements that it can accomplish. Because of these improvements, these authors have adopted this approach in their day-to-day accident reconstruction practice. In the spirit of helping others adopt this same approach, we offer the following step-by-step methodology for implementing this approach. These steps will focus primarily on the implementation of the equations reported in this article and they will presuppose that the analysts has already brought standard and accepted techniques and available test data to bear on analyzing the physical evidence from the rollover and spatially analyzing the vehicle motion.

1. Produce a scaled scene diagram containing the physical evidence from the rollover and vehicle positions along the roll path that are determined from this physical evidence.

Measure the total roll distance and the distances between each of the intermediate positions determined from the physical evidence.

2. Select values, or ranges of values, for the average and initial deceleration rates.

3. Calculate the velocity-distance history for the vehicle using the following equation:

In this equation, f0 is the initial deceleration rate, favg is the average deceleration rate, droll is the total roll distance and di is any discrete position along the roll path.

4. Calculate the average velocity between each set of reconstructed vehicle positions.

5. Calculate the time that elapsed between each set of reconstructed positions with the following equation:

The term d2– d1 is the distance separating two consecutive reconstructed roll positions vavg,1-2 is the average velocity between those positions. Summation of the individual segment times yields the elapsed time for the entire roll event. These times also enable plotting of the translational velocity-time history for the vehicle.

6. At each reconstructed vehicle position along the roll path, measure the roll angle in degrees. The roll angle should be measured additively, meaning that at the completion of one roll, the roll angle would be 360 degrees, at the completion of two rolls, the roll angle would be 720 degrees, and so on. Also calculate the number of rolls accumulated at each position, which would be the roll angle divided by 360.

7. Calculate the average roll velocity between each set of reconstructed roll positions with the following formula:

In this equation, θroll,1 and θroll,2 are the roll angles at two consecutive reconstructed vehicle positions. Plotting the calculated roll velocities from this step yields the roll velocity-time history for the vehicle.

8. Plot the translational and roll velocity histories developed in the previous steps. Care should be taken when tabulating the data since translational velocities are calculated at vehicle positions while roll velocities are calculated as averages between positions. To plot the roll velocities, the times corresponding to midpoint locations between positions must first be approximated, or alternatively, the roll velocities at vehicle positions can be approximated. Both these techniques involve averaging between subsequent calculated values.

R

eferences 1. In this article, “rolling vehicle” will refer to a vehicle involved in a rollover crash, not a vehicle that is rolling on its wheels. "Deceleration" will be used in the common form rather than the more accurate term "negative acceleration". The reference is to the general center of mass not a vehicle fixed observation.

2. Carter, Jarrod, et al., “Rollover Dynamics: An Exploration of the Fundamentals,” Society of Automotive Engineers (SAE) Paper Number 2008-01-0172.

3. Rose, Nathan, Gray Beauchamp, “Development of a Variable Deceleration Rate Approach to Rollover Crash Reconstruction,” SAE Paper Number 2009-01-0093.

4. Rose, Nathan, Gray Beauchamp, “Analysis of a Dolly Rollover with PC-Crash,” SAE Paper Number 2009-01-0822.

5. Rose, Nathan, Fenton, Stephen J., Beauchamp, Gray, “Analysis of Vehicle-to-Ground Impacts during a Rollover with an ImpulseMomentum Impact Model,” SAE Int. J. Passeng. Cars – Mech.

Sys. 1(1):105-123 (SAE Paper Number 2008-01-0178), 2008.

6. Rose, Nathan A., et al., “The Influence of Vehicle-to-Ground Impact Conditions on Rollover Dynamics and Severity,” SAE Paper Number 2008-01-0194.

7. Rose, Nathan, Gray Beauchamp, “Development of a Variable Deceleration Rate Approach to Rollover Crash Reconstruction,” SAE Paper Number 2009-01-0093.

www.collisionpublishing.com

Collision 81

8. The greater the distance between Positions 1 and 2, the greater the error introduced by this approximation.

9. Luepke, Peter, et al., “An Evaluation of Laminated Side Window Glass Performance during Rollover,” SAE Paper Number 2007-01-0367.

10. Carter, Jarrod, et al., “Rollover Dynamics: An Exploration of the Fundamentals,” SAE Paper Number 2008-01-0172.

11. Rose, Nathan, Gray Beauchamp, “Development of a Variable Deceleration Rate Approach to Rollover Crash Reconstruction,” SAE Paper Number 2009-01-0093.

12. Carter, Jarrod, et al., “Rollover Dynamics: An Exploration of the Fundamentals,” SAE Paper Number 2008-01-0172.

13. Brach, Raymond M., Brach, R. Matthew, Vehicle Accident Analysis and Reconstruction Methods, SAE International, 2005.

14. Cooperrider, Neil K., et al., “Testing and Analysis of Vehicle Rollover Behavior,” SAE Paper Number 900366.

15. Hughes, Raymond J., et al., “A Dynamic Test Procedure for Evaluation of Tripped Rollover Crashes,” SAE Paper Number 2002-01-0693.

16. Keifer, Orion, et al., “Vehicle Linear and Rotational Acceleration, Velocity and Displacement during Staged Rollover Collisions,” SAE Paper Number 2007-01-0732.

17. Luepke, Peter, et al., “An Evaluation of Laminated Side Window Glass Performance during Rollover,” SAE Paper Number 2007-01-0367.

18. Luepke, Peter A., et al., “Rollover Crash Tests on Dirt: An Examination of Rollover Dynamics,” SAE Paper Number 2008-01-0156.

19. Orlowski, K. F., et al., “Reconstruction of Rollover Collisions,” SAE Paper Number 890857.

20. Gee, R. Shane, et al., “Analysis of a Real-World High-Speed Rollover from a Video Record and Physical Evidence,” 2008-01-1486.

21. Funk, James R., Luepke, Peter A., “Trajectory Model of Occupants Ejected in Rollover Crashes,” SAE Paper Number 2007-01-0742.

22. Funk, James R., et al., “Occupant Ejection Trajectories in Rollover Crashes: Full-Scale Testing and Real World Cases,” SAE Paper Number 200801-0166.

23. Asay, Alan F., Woolley, Ronald L., “Rollover Testing on an Actual Highway,” SAE Paper Number 2009-01-1544.

24. Asay, Alan F., Woolley, Ronald L., “Rollover Testing of Sport Utility Vehicles (SUVs) on an Actual Highway,” SAE Paper Number 2010-01-0521.

25. The photograph of a rolling vehicle that accompanies the first pages of this article was taken by Gray Beauchamp during the SUV Rollover Testing Program hosted by Woolley Engineering in August 2009, the results of which are reported by Asay in SAE Paper 2010-01-0521.

82 Collision

www.collisionpublishing.com

with

Right-Now Results™ Total Math Reporting™ Step-by-Step Math Equations S.M.A.R.T.™ Smart Math Accident Reconstruction Technology

Key Features • • • • • • • • • • • • • •

New S.M.A.R.T. equations, enter what you know, Calc Zone will do the rest Easy to understand interface Total Math Reporting You see ALL calculation steps, No Hidden Math You see ALL equations used A legitimate source for each & every equation References, tables and much more Write your entire report within Calc Zone Pro Copy/Paste Diagrams & Images to Your Reports Create Custom Designed Reconstruction Reports Complete Control of Printed Report Formatting Unique Reconstruction Project Management Create Your Own Personalized Header/Footer with Our Free Logo Maker Group Equations and Sections

• •

• • • • • • • • • • •

Vehicle Specifications, AutoStats™ Lite Included Research Center Includes NHTSA: Recalls, Complaints, Technical Service Bulletins & Investigations.

Built-in Calculator Automatic Hassle Free Licensing System No Annual Fees Copy/Paste, Equations, Results, Notes and More to or from Word Processors, Spreadsheets etc…

One Click Imperial to Metric Easy One Click Sensitivity Analysis Speed Analysis Rotation Analysis Momentum Crush Total Distance to Stop

Competitive Upgrades Available

30 Day Money Back Guarantee

www.collisionpublishing.com

15 Day Free Trial

Collision 83

Back to Table of Contents

Retrieving and Interpreting Data from Ford Powertrain Control Modules using the

l o o T l a v e i r t e ta R

a D h s a r C h c s o B

84 Collision

www.collisionpublishing.com

B

ackground In the fourth quarter of 2007, Bosch released its Version 3.0 software update and made new hardware available to its Crash Data Retrieval Tool users.

This particular update included the new ability for the CDR Tool user to retrieve data from certain Ford powertrain control modules (PCM). The added ability to download crashrelated data from PCM’s was significant, as previous data from Ford’s restraint control modules (RCM) did not include pre-collision data, such as that found in many General Motors airbag control modules.1 With the addition of the Ford PCM data, CDR data analysts are now able to evaluate the pre-impact conditions of many newer Ford vehicles. The currently accessible Ford PCM’s record sixteen (16) data fields, including vehicle speed, brake switch status, ABS status, and engine speed.

The data is recorded at a sample rate of 5 Hz, or one sample every .2 seconds. The majority of the supported modules record about 25 seconds of data, but some record more than 6 minutes of data.

This paper will present methods to use in order to safely retrieve the data contained in the currently supported Ford PCM’s and methodologies used to interpret the retrieved data.

F

ord Powertrain Control Module Information In 2003, the first Ford vehicle models equipped with Electronic Throttle Control (ETC) were introduced to the market – the Ford Thunderbird and the Lincoln LS. Because of the necessity to integrate ETC within the powertrain control module, a newly designed PCM was warranted. In the process of developing the new PCM for the Thunderbird and the LS, Ford decided to include a data recording capability. As more Ford vehicles were introduced to the market equipped with ETC, more Ford models included the capability to record crash-related data. By 2007, approximately 70 percent of Ford models contained a PCM capable of recording crash-related data.

Bruce F. McNally McNally & Associates Accident Reconstruction Services, LLC www.collisionpublishing.com

Collision 85

In general, all Ford PCM’s record data at a rate of 5 Hz, or one sample every .2 seconds. All of the currently supported PCM’s record sixteen (16) different data parameters, some of which are particularly helpful in the reconstruction of collisions (for specific data found in the various supported Ford PCM’s, see Appendix A.) During normal operation of the vehicle, the PCM continuously records data from various components and sensors related to the vehicle’s powertrain. This recording begins when the vehicle’s ignition switch is turned to the “on” position and continues until the ignition switch is turned “off” or there is a power failure on the vehicle. The data is recorded in a circular buffer of either 2K or 32K, depending upon the model PCM. In a circular buffer, data is recorded sequentially until the buffer is full, whereupon the first information is overwritten and the process repeats.2

to severe collision that the Ford PCM is likely to function as an event data recorder. In a collision of sufficient severity to produce a deployment of the vehicle’s airbag system or seatbelt pretensioners, the vehicle’s Restraint Control Module (RCM) is designed to send a Restraint Deployment Signal (RDS) to the PCM. Once the PCM receives the Restraint Deployment Signal via the vehicle’s communication network, the PCM is designed to record five about (5) additional seconds of data and then stop recording new data.

For instance, in vehicles equipped with a PCM capable of recording 25 seconds of data, once the Restraint Deployment Signal is received by the PCM, the data buffer will contain about 20 seconds of pre-deployment data and about 5 seconds of post-deployment data. In those PCM’s that record more than six minutes of data, much more pre-deployment data is stored, while the device still only stores about 5 seconds of post-deployment data.

" "

Unlike some airbag control modules, where crash-related data can be stored in non-deployment events, it is not until a moderate

The primary methodology recommended by Bosch to retrieve data from a PCM is to connect to the module through the DLC.

F

ord PCM Interface Kit Prior to any attempt at retrieving data from a Ford vehicle equipped with a supported PCM, one must ensure that the necessary hardware is available to safely perform the data retrieval. Failure to follow the correct procedure will likely result in a failure to retrieve the data or, more importantly, result in the spoliation of the crash-related data contained on the PCM. The Ford PCM Interface Kit currently in use with Bosch software includes three direct-tomodule interface cables and the Ford PCM Adapter. The Ford PCM Adapter must be used in both Diagnostic Link Connector (DLC) and direct-to-module connections. The Ford PCM Adapter serves two primary functions in the data retrieval process – it provides sufficient power to the PCM for data retrieval and it sends a signal to the PCM, placing the PCM in a “diagnostic communication” mode. Attempting to use the PCM Interface Cables or the OBD II Vehicle Interface Cable without the PCM Adapter will result in the PCM being powered in the “run”

Figure 1: An example of a locked PCM data file that has been properly sorted by the CDR software.

86 Collision

www.collisionpublishing.com

mode, which may result in an overwrite of the data contained on the PCM if the data is not locked by recipt of the RDS.3 Use of the new CDR Power Supply Kit will help ensure that sufficient power is supplied to the PCM during the download process.

The new OBD II Vehicle Interface Cable includes additional connections within the cable that will allow the Ford PCM Adapter to communicate properly with the PCM. Use of the original issue OBD II Vehicle Interface Cable (Part Number 02002837) with the Ford PCM Adapter will result in failed communications with the PCM, and may result in spoliation of the PCM data. It is recommended that the old OBD II Vehicle Interface Cable be removed from the CDR Tool Kit and replaced with the new OBD II Vehicle Interface Cable so that inadvertent use of the old cable is averted.4

R

etrieving PCM Data The primary methodology recommended by Bosch to retrieve data from a PCM is to connect to the module through the DLC. Prior to attempting to retrieve data from a Ford vehicle, one should first check the CDR Tool Help File in order to determine which module(s) (RCM/PCM) are currently supported by the latest software version. If it is determined that the vehicle has a currently supported PCM, or has both RCM and PCM data, one should use the methodology described in the CDR Help Files to properly retrieve that data.

PCM. In cases where the electrical or communication system of the vehicle is compromised, and in cases where the vehicle damage otherwise prevents a DLC connection, a direct-to-module, or “bench download,” is possible. The direct-to-module connection can be performed either while the PCM is still mounted in the vehicle, or after the module has been removed from the vehicle.

There are three general types of powertrain control modules that can be currently queried using the CDR Tool – each requiring a different cable if a direct-to-module query is attempted. The CDR Help File will indicate which cable must be used for the given module type, and which of the three available wiring harness receptacles on the given module is used with that interface cable.

" " Once the Bosch CDR Tool is used to retrieve data from the PCM, the data must be interpreted by the reconstructionist in order to determine if it is related to the collision.

Prior to attempting to perform a retrieval of the PCM data, check the vehicle’s power system in order to determine if there is sufficient battery power to perform the download. The PCM download requires at least 9 volts of power in order for the PCM to power-up in the diagnostic mode. A voltage drop below 9 volts will result in the PCM resetting, and a potential loss of crash-related data. It is recommended that the download be performed with a full 12-volt battery charge, since it is possible to quickly drain down a battery on a damaged vehicle during the download process.

While checking the vehicle’s electrical system, do not turn the ignition key to the “on” position. Turning the ignition key to the on position may result in an overwrite of the data contained on the PCM if the data on the PCM is not “locked” by the Restraint Deployment Signal and the Ford PCM Adapter is not yet plugged into the DLC or the adapter signal isn't reading the PCM.

It is important to understand that it is possible that the vehicle may have sustained damage to its electrical or communication system during the collision. If the communication wiring between the vehicle’s DLC and the PCM is compromised, it is possible for the Ford PCM Adapter to emit a green ready light, but not be communicating the diagnostic mode signal to the PCM. In cases where there is unlocked data on the PCM, the data will begin to be overwritten as soon as the ignition key is turned to the run position. If there is any question about the integrity of the vehicle’s electrical or communication system, one should not attempt data retrieval through the DLC, and instead connect directly to the PCM for the download.

While the Bosch Help Files indicate that the preferred manner in which to retrieve PCM data is via the Diagnostic Link Connector, the data may also be safely retrieved by connecting directly to the

I

nterpretation of “Locked” PCM Data Once the Bosch CDR Tool is used to retrieve data from the PCM, the data must be interpreted by the reconstructionist in order to determine if it is related to the collision. In cases where the PCM received a Restraint Deployment Signal (RDS) from the RCM after deployment, the CDR software will alert the user that the PCM data is locked, and will automatically sort the data file so that the pre-RDS data is listed prior to the post-RDS data. This data sorting occurs in both the tabular and graphical output formats in the CDR software.

While the CDR Tool can display the data retrieved from the PCM in both tabular and graphical format, it is often helpful to use a spreadsheet program (ie. Excel) to display the data for interpretation purposes. In the spreadsheet, the analyst can look for unusual data readings in all of the available fields and make notations within the data for later reference. The use of the spreadsheet also allows the analyst to add additional fields to the data, such as calculating elapsed distance over a specific time frame. This type of analysis is helpful in correlating the PCM data to the physical evidence collected at the crash scene.

I

nterpretation of “Unlocked” PCM Data Shortly after Bosch introduced PCM data retrieval commercially to accident reconstructionists, it became apparent that the system of locking data was susceptible to power interruption problems and the potential overwrite of crash related data. In reviews of cases where a RDS was not received by the PCM, but a deployment did occur, it was found that a large number of the

www.collisionpublishing.com

Collision 87

Figure 2: An example of an unlocked PCM data file created during a hard braking incident. In order to sort this data into its proper order, the data contained on the left portion of the graph must be placed to the right of the data seen on the right edge of the graph.

Figure 3: An example of an overwrite of data caused by turning on the ignition switch without attaching the PCM Adapter. Note that the overwrite has occurred at the beginning of the memory buffer and continues for several seconds before the ignition was turned off. power interruptions likely occurred when the hood of the vehicle was displaced into the top of the battery, causing a short circuit at the battery. In other cases, the battery was destroyed early on in the collision, and while the RCM had reserve power to deploy the airbags, the PCM does not have a built-in power reserve and attempted communication of the RDS from the PCM simply was not received by the PCM. If proper steps are taken immediately after the collision, useful data may still be retrieved from the PCM in cases where a RDS was not received by the PCM. Even with proper steps being taken after a collision, it is not unusual to see an overwrite of some of the 88 Collision

crash related data when a power interruption has occurred. Careful evaluation of the crash data is imperative in unlocked PCM data files, as the manner in which the data is overwritten can sometimes make it difficult to identify where a collision occurred within the data set.

In most cases where the analyst is reviewing an unlocked PCM data file, the data is sorted by identifying the point where the vehicle experienced a larger change in speed than can be justified by simply applying the brakes. This sudden change in speed is assumed to be the reading where impact occurred, and the data is sorted accordingly. When sorting an unlocked PCM data file, one should

www.collisionpublishing.com

Figure 4: A review of the data tables for indicates that the PCM reset and overwrote 6.5 sec of data at the top of the memory buffer. remember that a power failure may result in no “post-impact” data being written and in cases where the PCM simply did not receive an RDS, more than 5 seconds of post-impact data may be written.

P

ower Interruption Issues If a loss of power to the PCM occurs prior to a Restraint Deployment Signal being received by the PCM, in most cases an “unlocked” PCM data file will likely be retrieved from the module. When evaluating power interruption issues on a PCM data file, it is helpful to first understand the manner in which the data is stored within the module's memory buffer.

During a power-up of the PCM, data is continually stored in the circular buffer of the PCM. The first memory address used in the circular buffer is identified in the PCM data file as EA000010.

In a 25-second PCM data file, the memory addresses range from EA000010 to EA0007F0, for 127 lines of data. Each line of data within that range represents the information recorded by the PCM every .2 seconds (5 Hz).

As previously pointed out, in an unlocked PCM data file, an application of power to the PCM for more than about 25 seconds will result in a complete overwrite of collision-related data. While this statement is correct, the uninformed investigator might conclude that as long as the overwrite was some time period less than 25 seconds, the data at or near the time of the collision will still be stored on the module. This is simply not the case.

One should understand that when the PCM loses power, it does not simply begin to record data where it previously left off in the circular buffer. Each time the PCM reboots, it begins to record at memory address EA000010. In an unlocked PCM, losing power will likely result in the data file being split, causing a loss of contiguous data. For instance, if the collision happened to have occurred at EA000050, a single reboot of the module and one second

of power application will result in an overwrite of the last second of pre-crash data.

Fortunately, it is relatively easy to identify when an overwrite of data has occurred due to a reboot of the module. By reviewing the "Key-On Timer" data value, one can determine if the module has rebooted, as the timer will also reset during a reboot. If there is discontinuity in the "Key-On Timer" data, it is probable that an overwrite of the data has occurred and the file must be sorted with that in mind. How much data has been overwritten can be determined by the amount of contiguous data contained after memory address EA00010, the starting memory address in the buffer.

U

nusual Power Interruption Issues An unusual “locked” PCM data file can be stored on the PCM in cases where a short-duration power fluctuation - causing a reboot of the PCM - occurs near the time of deployment of the restraint system. The occurrence of this type of event can cause difficulty during the analysis of the PCM data, as the Bosch CDR Tool Software is not designed to analyze the data contained in the file to identify that a power fluctuation has occurred.

In a “Locked-Reboot” data file, power to the PCM has dropped below 9 volts for a short time period, causing the PCM to reboot.

This reboot is almost immediately followed by a RDS being received from the RCM, which is not as susceptible to power fluctuations due to its onboard capacitors. Since the PCM has rebooted before receiving the RDS from the RCM, when power is restored to the PCM, it begins to overwrite the data, starting at memory address EA000010. Meanwhile, the RCM continues to send the RDS to the PCM for as much as .6 or .8 seconds after deployment occurs. Once the RDS is received by the PCM, five additional seconds of data is recorded by the PCM before it stops compiling data in the memory buffer.5

www.collisionpublishing.com

Collision 89

Figure 5: Example of a “Locked-Reboot” PCM data file. The actual impact can be seen on the left portion of the graph, and has been incorrectly sorted by the CDR software. Manual sorting of this type of file is necessary.

Figure 6: Hex Data information included near the back of a CDR Report. The top three blocks of data include the VIN, the PCM Part Number and the PCM Calibration Level. The first and last lines of recorded data are EA000010 and EA0007F0, respectively.

90 Collision

www.collisionpublishing.com

Figure 7: Data from the example “Locked-Reboot” data file sorted so that it is in its proper memory buffer address order.

The CDR Tool Software has an automatic sorting feature - recognizing when a retrieved PCM file contains a RDS – placing the PCM in its “proper” chronological order with the post-RDS data at the end of the list. In most situations, this feature of the software streamlines the analysis of the data file, as the reconstructionist does not have to initially sort the data manually. Although a “Locked-Reboot” data file will be sorted so that the post-RDS data is at the end of the file, it is almost certain that the data is incorrectly sorted. The automatic sorting function of the software may result in the uninformed analyst misinterpreting the data file.

There are three data fields that must be examined in order to properly identify a “Locked Reboot” data file; the "Key-On Timer", the "RDS Signal", and "Buffer Address" parameters. If the RDS Signal was initially received by the PCM in Buffer Addresses EA000010 to EA000030, and the "Key-On Timer" starts counting upward from .25 seconds at Memory Address EA000010, you most-likely have identified a “Locked-Reboot” data file. Once the data file has been properly identified, the process of sorting the data into its proper time-line can be accomplished.

written after the PCM reset and, therefore, how much data was overwritten during the reboot. The proper order of the memory buffer can be found by reviewing the HEX data table found at the end of the CDR Tool report, an example of which is shown in Figure 6.

" " The CDR Tool Software has an automatic sorting feature - recognizing when a retrieved PCM file contains a RDS

The PCM data depicted in Figure 5 has been identified as a “Locked-Reboot” data file. A simple review of the graph provided by the CDR Tool Software clearly shows that the vehicle experienced a significant impact that has been sorted so that it appears relatively early on in the pre-impact data. While the graph indicates that the collision event is clearly included in the PCM data file, the data file must be manually sorted so that it appears in the appropriate chronological order.

When analyzing a Locked-Reboot data file, it is recommended that the analyst use a spreadsheet program to place the data into its appropriate memory-buffer-order to evaluate how much data was

After sorting the data into its proper Hex Address order, one can better understand what data in the PCM file was overwritten during the reboot of the module and its relationship to the remaining data. In the example file, it can be seen that the remaining collision data contains approximately 3.4 seconds of data, with about .8 seconds of data occurring after impact and approximately 2.4 seconds occurring prior to impact.

www.collisionpublishing.com

Collision 91

Figure 8: During the second sort, the post-RDS data and the impact data is placed to the right of the oldest pre-impact data.

Figure 9: During the final sort of the data, the post-RDS data is placed at the end of the graph, leaving a blank space between the impact data and the oldest pre-impact data to account for the overwritten pre-impact data.

In this example, because of the reboot of the PCM just prior to it receiving the RDS, there is approximately 5.2 seconds of preimpact data that was overwritten. The overwritten data includes that which would have told us what was occurring on the vehicle in the time frame between 2.6 and 7.8 seconds prior to impact.

Because of the gap in pre-impact data that must be included in the analysis, the final sorting of data will include more than the “normal” 20 seconds of pre-RDS data. In this case, there is 25.4 92 Collision

seconds of pre-RDS data, with about 5.2 seconds of that data being unknown because of overwrite. The process of sorting the data can be seen in Figures 7 through 9

S

ummary The process of retrieving data from a supported Ford PCM is a relatively straightforward and simple process, but there is a very real potential for evidence spoliation if the pro-

www.collisionpublishing.com

cedures outlined in the Bosch CDR Help Files are not followed.

Although retrieval of the data contained on the PCM is almost always easily accomplished, interpretation and appropriate timerelative sorting of that data is sometimes complicated by power interruptions that occur as a result of the collision, or communication interruptions between the RCM and the PCM that results in the PCM not receiving a Restraint Deployment Signal.

Understanding how the PCM records data – particularly as it relates to the issues that arise when a power interruption occurs – will assist the analyst in understanding what data was likely overwritten in an unlocked data file. This process can be as simple as a single cut-and-paste when using a spreadsheet, but can become much more complicated if the actual collision data is overwritten, or in the case of the relatively uncommon occurrence of a “LockedReboot” data file.

R

eferences 1. Wheelock, Robert J. (Bob), Presentation: "Current Ford Event Data Recorders," SAE Government/Industry Meeting, May 15, 2007.

2. Espanol, et al. v. Ford Motor Company, et al., Case No. BC345611, County of San Mateo, California, Deposition of James J. Engle, January 24, 2007.

3. Robert Bosch, LLC U.S.A., CDR Version 3.3 Software CD, 2009.

4. Ibid.

5. Ruth, Richard R., Personal correspondence with Bruce McNally, July 23, 2008.

A

cknowledgements I would like to thank Mr. Richard Ruth, of Ruth Consulting, for his assistance in explaining the issues regarding a “Locked-Reboot” PCM data file. I would also like to thank Wade Bartlett, of Mechanical Forensic Engineering Services, for his assistance during testing of unlocked PCM data files.

Appendix A Buffer Address

The hex address of the PCM circular buffer where a group of data is stored.

Restraint Deployment Signal

A signal sent by the Restraint Control Module to the PCM if the RCM commands a deployment of the airbags or seatbelt pretensioners. The PCM monitors this signal status and records if an RDS has been received from the RCM.

Accelerator Pedal %Full

Accelerator pedal position in percent of full.

Engine Throttle %Full

Throttle valve percent open (on engine).

Brake Switch

On/Off status of brake pedal switch used to control brake lights.

Brake SC De-ac

On/Off status of brake pedal switch used to deactivate the cruise control. Off means the pedal is not sufficiently depressed to deactivate the speed control system, while On means that the brake pedal has been sufficiently depressed to deactivate the speed control system.

ABS

Status of antilock brake system. Active means that sufficient brake pedal application has occurred to activate the ABS system, while inactive means that the ABS system is not actively functioning.

Transmission-Neutral

Neutral transmission gear status. A 'Neutral' value means the transmission indicator was in the neutral position, and a ‘Not Neutral’ value means the indicator switch was in any position other than neutral.

Transmission–Reverse

Transmission in reverse gear indicator. A ‘Reverse’ value means the transmission indicator was in the Reverse gear position, and a ‘Not Reverse’ value means the indicator switch was in any position other than Reverse.

Speed Control

Status of the speed control On/Off.

Engine RPM

Engine Revolutions Per Minute.

Engine Revolutions Per Minute.

Commanded torque at wheels (calculated).

Wheel Torque Actual (calculated)

Actual torque at wheels (calculated).

Traction Control

The status of the traction control system is reported as Active or Inactive.

Stability Control

The status of the Integrated Vehicle Dynamics system is reported as Active or Inactive.

Key on Timer – 63.75 Max (sec)

Key on Timer starts when power of more than 9 volts is applied to the PCM. The timer begins with an initial count of .25 seconds and counts upward to 63.75 seconds, after which it remains at 63.75 seconds until the ignition switch is cycled off and then on again.

Vehicle Identification Number

This number is stored in the PCM, and is independent of the information input by the technician at the time of data retrieval.

PCM File Name (calibration level)

The calibration file name is stored in the PCM and is included in the retrieved data.

PCM Part Number

This data is stored on the PCM and retrieved during download of data.

Relative Time

This data element is only calculated by the CDR Software in data files where a Restraint Deployment Signal has been received by the PCM. Adapted from Bosch CDR Help File www.collisionpublishing.com

Collision 93

Accident Reconstruction Calculator TM

By WeCARE Products and Education

Why do your calculations by hand?

The Accident Reconstruction Calculator™ provides you with a complete suite of equations.

Momentum Time-Distance Basic Motion Low-Speed Auto-Pedestrian

Energy Force Delta-V Crush Projectile Motion and more…

The equations you grew up with. Take the guesswork out of your work with this user-friendly program that has benefited over 500 police agencies and accident reconstruction firms throughout the United States. Visit our website for current price and order form. While browsing our website, take a look at other collision reconstruction products and our training classes as well.

WeCARE Products 4804 Granite Dr., Suite F3-113, Rocklin, CA 95677 Bus. (877) 944-5903 Fax (530) 836-1673 WeCARE@rudydegger.com http://www.rudydegger.com/wecare-products

Providing affordable lab grade triaxial accelerometers for professional, reliable testing Instrumented Sensor Technology 4704 Moore Street Okemos, MI 48864 USA info@isthq.com Phone: (517) 349-8487 Fax: (517) 349-8469 Web: www.isthq.com

The provider of choice for accelerometers used by the Collision Safety Institute and the ARC-CSI Crash Conference

Common

Back to Table of Contents

Post-Impact

Speed Analysis

Greg Russell Accident Analysis & Reconstruction Inc

96 Collision

www.collisionpublishing.com

C

rash reconstructionists often encounter situations where vehicles may, at least initially, remain engaged post impact. In some cases, they may travel as a single unit until they reach their final rest positions, while in other cases some post impact event my cause them to separate before reaching their respective final rest positions. In either case, for all practical purposes, the vehicles will have the same or a “common” post-impact velocity (admittedly, if the vehicles are rotating their centers of mass may be traveling at slightly different post-impact velocities, but again for all practical purposes, any differences in the linear center of mass postimpact velocities will be insignificant.) In these situations, if just one velocity for one of the involved vehicles can be quantified along with their respective weights (masses) and approach and departure headings, the remaining velocities may be calculated using only the conservation of linear momentum. No additional information regarding their post impact movement, such as a coefficient of friction while moving to rest, vehicle braking efficiencies, or post impact distances needs to be separately quantified. The case example in this narrative will better illustrate this analytical technique.

Assume that Vehicle #1 was stopped along the westbound shoulder of the roadway when it attempted to complete a U-turn. In the process of making the U-turn, it moved in

front of Vehicle #2, which had been traveling westbound.

On impact, Vehicle #1 was struck in the side between the wheels by Vehicle #2. Post impact, both vehicles initially traveled together as one unit until the rim of one of Vehicle #1’s wheels began to dig into the roadway, causing Vehicle #1 to rotate off the front of Vehicle #2 in a counterclockwise direction. Vehicle #1 then moved around the collision scene, eventually coming to rest on the westbound shoulder, just west of where it had originally started out from.

Vehicle #2 came to rest in the middle of the roadway leaving little to no post-impact movement information.

There was little definitive post-impact evidence that could be used to quantify an accurate post-impact velocity for either vehicle. However, there was sufficient evidence to reliably identify the approach and departure headings of both vehicles, and as already stated, it was known that Vehicle #1 had attempted a U-turn from a stopped position on the shoulder.

Through a series of acceleration tests, attempting to complete the same U-turn that Vehicle #1 was negotiating when it was struck, it was established that Vehicle #1 would have been traveling approximately 12 miles per hour at impact having moved from its original stopped position to the area of impact.

www.collisionpublishing.com

Collision 97

Figure 1: Vehicle 1

Figure 2: Vehicle 2 98 Collision

www.collisionpublishing.com

Figure 3: Diagram With this impact speed information for one vehicle – together with vehicle weights and approach and departure headings - there is sufficient information to estimate the impact velocity of Vehicle #2 along with the post-impact velocity of both vehicles.

Working from the standard conservation of linear momentum equation, the sine of the approach and departure headings are taken in order to convert the angular relationship of the collision to a linear one as seen in equations 1 and 2. ( Eq 1) (Eq 2) Inasmuch as we know, in this situation, that both vehicles have a common post-impact velocity, the post-impact subscript may be dropped from the post-impact equation variables, leaving equation 3:

(Eq 5)

(Eq 6) Since the impact velocity of Vehicle #1 is known and the impact velocity of Vehicle #2 along with the post impact velocities are unknown, Vehicle #1’s impact velocity needs to remain in the equation and one of the other terms has to be removed. Since there are two angles associated with the common post- impact velocity, the term that has to be canceled from the equation are those values associated with the impact velocity of Vehicle #2. Therefore, 65 degrees, the approach heading of Vehicle #2, has to be subtracted from all the angles as seen in equation group 7.

(Eq 3) The common post impact velocity may now be factored out on the right side of the equation yielding equation 4.

(Eq 4) At this point, the momentum equation only has three velocity variables instead of the mo commonly observed four. Because one of the velocity variables may be canceled from the equation by adjusting the related angle to 0 degrees, an equation may be written where there is only 1 known velocity variable and 1 unknown variable as seen in equation 5. Then, when we replace the variables with the identified (known) quantities we find equation 6.

(Eq 7) Solving for the left side of the equation and the items inside the parenthesis on the right side of the equation leaves us with: Dividing both sides by -1664 to solve for the common post-impact velocity leaves us with:

www.collisionpublishing.com

Collision 99

Figure 3: Tire mark and rim gouge

Table 1: CDR Report Data from Vehicle #2 100 Collision

www.collisionpublishing.com

Having now solved the post-impact velocity for both vehicles the same equation may be used to solve for the impact velocity of Vehicle #2 as seen in equation 8.

(Eq 8) By adding the calculated post-impact velocity to the equation we find equation 9.

When the change in velocity is calculated for Vehicle #2 from the data obtained in the “traditional” linear momentum analysis detailed previously in this narrative, the calculated change in velocity for Vehicle #2 was 16.8 miles per hour as seen in equation group 11. Clearly, that’s generally consistent with the downloaded data particularly given the CDR report data is limited to the longitudinal axis whereas the calculated delta-V would be for the center of mass of the vehicle to include redirection and the lateral component.

(Eq 9) Since the impact velocity of Vehicle #1 is already known and its approach heading is already assumed to be 0 degrees, no adjustments have to be made to the angles in order to solve for the impact velocity of Vehicle #2 as seen in equation group 10.

(Eq 10) In this particular collision, Vehicle #2 was equipped with a Bosch CDR System supported (accessible) airbag control module that recorded a maximum change of velocity (delta-V) of 16.25 miles per hour at 111 milliseconds as seen in Table 1 from the “CDR report”. The CDR report delta-V depicts acceleration data and a cumulative delta-V for 111ms and, near the “end” of that data as graphed (Table 1) the acceleration hasn’t “returned to (around) zero;” however, the wave shape appears to have largely flattened out and, given the dynamics of this crash, would be consistent with an “end of event” as suggested by the module stored data around 111ms along the longitudinal axis.

(Eq 11) As an aside, the posted speed limit on the roadway where this collision occurred was 40 miles per hour, and the driver of Vehicle #2 stated that he was traveling approximately 40 miles per hour when Vehicle #1 suddenly turned out in front of him.

S

ummary With this approach, the post-impact velocities of both vehicles as well as the impact velocity of Vehicle #2 were calculated using only the Conservation of Linear Momentum.

Yet, other than the departure headings of the vehicles, there was no post-collision data used in the calculations. There was no need to be concerned with the coefficient of friction of the roadway, or the braking efficiency of the either of the vehicles, which would be very problematic to otherwise establish in this case.

While reconstructionists often approach a crash with the idea that, to use a linear momentum analysis, one needs to know post impact speeds, this technique illustrates that not to be the case and the analysis can be completed with “less” information and still yield an acceptable result.

Accident Reconstruction Calculator TM

By WeCARE Products and Education

Why do your calculations by hand?

The Accident Reconstruction Calculator™ provides you with a complete suite of equations.

Momentum Time-Distance Basic Motion Low-Speed Auto-Pedestrian

Energy Force Delta-V Crush Projectile Motion and more…

The equations you grew up with. Take the guesswork out of your work with this user-friendly program that has benefited over 500 police agencies and accident reconstruction firms throughout the United States. Visit our website for current price and order form. While browsing our website, take a look at other collision reconstruction products and our training classes as well.

WeCARE Products 4804 Granite Dr., Suite F3-113, Rocklin, CA 95677 Bus. (877) 944-5903 Fax (530) 836-1673 WeCARE@rudydegger.com http://www.rudydegger.com/wecare-products

Vericom VC4000DAQ Performance Computer Y

Z

New tri axis 2G to 6G accelerometer up to 1000 Hz sample rate. Infinite storage time.

X

2G to 100G 1 to 1000 Hz

External accelerometers 10G to 100G.

Super easy to install and completely portable, single suction with ram mount, auto digital leveling (self leveling).

Compatible 5 Hz

♦ OBDII & CAN input. ♦ Up to 16 sensors input.. ♦ Firmware & software updates from internet. ♦ Simple calibration check.

Vehicle Rotation begins

GPS Speed

Vericom Speed

0.00

60

Angular Rate Gyro

GPS Speed

-0.10

50

-0.20

Lateral G

Vericom Distance

-0.30

Compass Heading

40 Gyro (Deg/Sec)

Acceleration (G)

(compass) built-in.

PC Communication by • USB port.

• Bluetooth up to 100 meters.

• SD Card.

• 3 RS232 ports.

• Streaming data.

GPS

0.10

N 360° magnetometer

Built-in angular rate gyro (yaw or pitch)

-0.40 -0.50

Deceleration

-0.60

Braking

-0.70 -0.80

30

CSY

20

10

-0.90 -1.00 0

1

Time (Sec.)

0

2

9

10

11

Display Average Table 2/18/2008 Date & Time 9/24/2002 09:18 AM 9/24/2002 09:19 AM 9/24/2002 09:21 AM 9/24/2002 09:22 AM 9/24/2002 09:23 AM 9/24/2002 09:25 AM 9/24/2002 09:27 AM Average of Runs

Run No. 4 5 6 7 8 9 10

Time Sec 1.95 1.95 1.95 3.46 3.41 3.35 4.13

Acceleration Average G -0.891 -0.887 -0.882 -0.897 -0.897 -0.895 -0.892

Speed MPH 38.10 37.95 37.74 68.07 67.06 65.74 80.80

Distance Feet 56.6 55.8 56.2 178.5 172.4 168.4 253.4

2.89

-0.891

56.50

134.5

12

13

14 15 Time (Sec.)

16

17

18

19

Range Table f Speed Result 0.80 57.88 0.81 0.81 0.83

58.24 58.60 58.96

0.84 0.85 0.86 0.87 0.88

59.31 59.66 60.01 60.36 60.71

Phone 763-428-1381 USA or Canada 800-533-5547 fax 763-428-1381 info@vericomcomputers.com www.vericomcomputers.com 14320James Road - Suite 200 - Rogers, MN 55374

Back to Table of Contents

EDR Module Types and Collision Data Available in CDR Supported Vehicles 104 Collision

www.collisionpublishing.com

A

bstract Numerous electronic modules in motor vehicles store collision-related information.

This information can be accessed with the Bosch Crash Data Retrieval (CDR) System.

However, different vehicles are capable of storing different information. The type of information stored is specific to the type of module with which the vehicle is equipped rather than the vehicle itself and, in some circumstances, to the options on the vehicle.

In some cases, the information stored in a vehicle may be of little value to the person reconstructing the collision. Under such circumstances, the need to obtain the information may be outweighed by the cost associated with accessing the module. Alternatively, if it is known that there is considerable useful information available, the parties involved may take extra steps to preserve the vehicle until the module(s) can be accessed.

Because of this need, a database was established that links each vehicle covered by the CDR System with its module type and the data that the module may contain.

Chuck Veppert

Valley Technical Services www.collisionpublishing.com

David Little,

Baker Materials Engineering Ltd Collision 105

I

ntroduction Following a motor vehicle collision, an investigator can readily establish if the vehicle has an accessible event data recorder (as found in an ACM, PCM or ROS1) by searching the Help files in the latest version of the Bosch CDR program. However, just knowing that a vehicle is supported does not tell the investigator what type of information may be stored in that particular vehicle's module. The data may range from nothing more than driver’s seatbelt switch circuit status, such as in a 1998-1999 Pontiac TransSport, to something far more revealing such as 25 seconds of all the pre-impact and impact information that an investigator could ask for as can be found in many mid to late 2000 model years Fords with PCM and ACM coverage.

G

eneral Motors General Motors was the first manufacturer to allow access to their modules with the CDR System and, understandably, currently have the most module types accessible, at 32. These include 30 ACMs and two ROSs. Table 1 of the GM modules currently supported.

ACM

ROS

SDM A

SDM DG2002

ROS B

SDM B

SDM D2002

ROS C

SDM CL2 1997

SDM GT2001

In many cases, a considerable amount of time and money must be expended to access the ACM, PCM and/or ROS. These expenses may include airfare and extended travel time, or possibly special cutting tools that may be only available through a local fire department. Deciding how much effort to expend to access an event data recorder can be made significantly easier if the investigator can establish what specific information may potentially be retrieved from that vehicle.

SDM CL2 1999

SDM GF2002

SDM E

SDM GT2002

SDM I

SDM GS

SDM R

SDM DW2003

SDM S

SDM EPSILON

SDM RSDD

SDM EPSILON 2005

This need led to the formation of a database where the collision data in each module type has been identified and the module types for most vehicles covered by the Bosch CDR system have been categorized. Knowing the make, model and year of the collision vehicle, an investigator can now better identify what type of data will likely be stored in the vehicle of interest before heading to the vehicle.

SDM U

SDM EPSILON 2006

SDM G1999

SDM DS2005

SDM G2000

SDM C

SDM G2000S

SDM DC2007

SDM G2001

SDM AB9

SMD DG2001

SDM CGDELPHI Table 1

D

atabase This database was originally compiled by the same authors for the 2006 CDR User’s Conference2. At that time there were only 21 modules identified as supported by the CDR System.

Currently there are over 50 module types that have been identified as supported and more will certainly be added to this list as newer modules are identified and as more vehicles become supported in coming years.

Module types can be identified by accessing the electronic version of the .cdr file with a program such as Word or Notepad. By rightclicking on the file, the program can be opened in a text file. The second line of the file identifies the module type, as shown in figure 1. However, it is important to ensure that the file is never altered or saved when viewed by this method, as doing so would prevent the CDR program from being able to open the file again.

An electronic spreadsheet was generated for each of the three manufacturers (GM, Ford and Chrysler) that have vehicles currently supported by the CDR System. Each spreadsheet consists of a main worksheet that lists the make, model and year of vehicle, with the module type listed. The module type is hyperlinked to a worksheet that details the information available in that type of module.

The earliest model year GM that can be accessed is 1994. These early modules typically included only data captured at the time of the collision, including longitudinal speed change (delta-V), driver’s seatbelt switch circuit status and number of ignition cycles. GM modules did not start phasing in pre-impact information until 19993. Typical pre-impact information for early 2000 GM vehicles included five samples of vehicle speed, throttle position and engine rpm, plus eight samples of brake switch circuit status, all sampled at 1 Hertz. This data expanded with the introduction of the CAN bus4 vehicles around 2005. Other data captured with these modules included outside air temperature, transmission selector position, cruise control state, accelerator pedal position, ABS state, yaw rate, steering wheel angle and so on.

F

ord Ford vehicles were first supported by the CDR program starting with model year 2001. Currently there are 10 Ford modules that can be downloaded. These include seven ACMs and three PCMs, as outlined in table 2.

Figure 1 106 Collision

www.collisionpublishing.com

ACM

PCM

ARM 100

PCM-1a

RCM1

PCM-1b

Takata

PCM-2

Takata 2 RC5 RC6 AB9 Table 2 Early modules, such as the RCM1, captured a limited amount of useful collision information. There were no ignition cycles, no seatbelt use status, and no pre-impact information. Only the collision acceleration pulse and the calculated delta-V were potentially of any significance, from a reconstruction perspective, and the short duration of 116 ms limits this value.

Access to pre-impact information was introduced with two MY03 Fords. This information was available in the PCM, although this module did not capture any impact data (seatbelt use, delta-V, etc.). The PCM provided a much higher sampling frequency (five samples per second) than the GM modules, and extended over a longer time (12.4, 25.2 or 409.2 seconds, depending on the module). With some vehicles, both the crash data in the ACM and the pre-crash data in the PCM could be accessed.

The pre-impact information in some Fords was finally combined with the impact data in the ACM starting with model year 2006.

Pre-impact information is available for 5 seconds at 1 or 2 Hz in the RC5, RC6 and AB9 modules. The AB9 module is the first module that is used by more than one automobile manufacturer: both GM and Ford use the AB9. Although the AB9 modules used by both automobile manufacturers are made by Bosch, they are configured to record different data sets.

In several model vehicles, where both ACM and PCM modules had been accessible but now only the ACM is accessible using the CDR System (in some 2008 – 2010 vehicles), pre-impact data has been found to still be present in the PCM. This data has been obtained using earlier, supported VINs from the same model of vehicle. However, whenever information is accessed by this method, adequate testing should be conducted on the same year of vehicle as the unsupported vehicle in order to validate the data.

C

hrysler Coverage of Chrysler vehicles began with one model in 2004– the Dodge Durango. This model was subsequently removed from the coverage list. Currently, the first model year that can be accessed is 2005. There are 10 Chrysler modules that can be accessed, eight of which are listed in table 3.

ACM Bosch CHRY0152

TRW CHRY0152

Bosch CHRY0154

TRW CHRY0154

Bosch CHRY0156

TRW CHRY0204

Bosch CHRY0303

TRW CHRY 0401

Table 3 All of these modules contain pre-impact data. As indicated previously, some of the modules can not be accessed with the CDR System. It appears that these modules were only made by Bosch.

However, relevant crash data may still be stored in these modules and may be accessed by Chrysler in concert with Bosch.

Some modules (CHRY0152 and CHRY0156) captured two sec-

onds of pre-impact information at 10 samples per second – the highest resolution so far. This information includes vehicle speed, engine rpm, throttle percent, pedal percent, brake switch status, electronic stability program status, electronic throttle control status and cruise control system status. However, there is no collision information included, such as crash acceleration, delta-V or seatbelt buckle status.

Other modules capture five seconds of pre-impact information and the longitudinal acceleration experienced during the collision.

However, these modules must be downloaded with CDR Version 3.1 or later in order to get all five seconds of pre-impact data and the crash pulse. Downloading with an earlier software version will only provide two seconds of pre-impact data in these modules, and no crash pulse.

It was also noted that modules saved prior to CDR Version 3.1 were named DCX0152, DXC0154 and DCX0156. However, if the same module is downloaded with Version 3.1 or later, or if the file is saved without the sequence numbers (last six digits of the VIN) using software version 3.1 or later, then the letters ‘DCX’ are replaced by ‘CHRY’. Simply opening the file with a later software version and saving the file with changes to the Comments section will not change the original module type name.

More pre-impact information was added to some of the later modules (CHRY0303 and CHRY0303C) including panic brake assist status, steering angle, yaw rate, individual wheel speeds, shift gear position and individual tire pressures. Collision data was expanded beyond the longitudinal crash pulse to record the lateral acceleration and the angular roll rate. Currently, however, none of the Chrysler modules that have been examined record seatbelt buckled status.

The capability for Chrysler vehicles to store non deployment events started in 2009 with one model - the Dodge Ram 1500. This coverage expanded in 2010 to include 14 models. These modules store non deployment events in compliance with NHTSA 49 CFR Part 563, meaning that a trigger threshold of 8 km/h in 150 msec must be met or exceeded in order for the event to be recorded.

C

onclusion The number of airbag control modules, powertrain control modules and rollover sensors that have currently been identified as accessible with the Bosch CDR System is in excess of 50. While there are similarities, Each module type stores different information. Earlier modules recorded limited useful collision information, while more recent modules contain a plethora of data.

In order to provide an investigator with the ability to determine what data may be contained in his or her vehicle of interest, a database was created. By simply knowing the make, model and year of the subject vehicle, the investigator can establish the module type with which the vehicle was equipped and the data that that particular module is capable of storing. This allows the investigator to decide if access to the data is warranted based on the associated cost (in time, effort and money) to obtain the module.

R

eferences 1 ACM = Airbag Control Module, PCM = Powertrain Control Module, and ROS = Rollover Sensor

Veppert, Charles and Little, David, “A Review of Various ACM Types and Data Comparison.” Proceedings of the Crash Data Retrieval User’s Conference, February 2006.

2

Reportedly, a limited number of 1998 fleet/rental vehicles were equipped with pre-impact information, although none of these have been seen to date.

3

4

Controller Area Network

www.collisionpublishing.com

Collision 107

Index of Articles

Collision Vol.1, Issue 1 through Vol. 4 Issue 2 www.collisionpublishing.com Accelerometers Effects of Sample Rates on Accelerometer Based Skid Testing and Unit Comparison: Volume 2, Issue 2, Pg 66 Quantifying the Aerodynamic Forces Acting on Objects during a fall: Volume 3, Issue 1, Page 14 Basic Integral Calculus For Crash Reconstruction: Volume 3, Issue 2, Page 56

ACM (Airbag Control Module)

Bus Braking Tests: With and Without ABS: Volume 3, Issue 2, Page 70 Hydroplaning: The Effect of Water on the Roadway: Volume 3, Issue 2, Page 78 Using Ford PCM Data to Evaluate Deceleration Rates, Brake Time and Impact Speeds: Volume 4, Issue 1, Page 74 Honda Gold Wing Motorcycle: Linked Brakes and Their Performance: Volume 4, Issue 2, Page 46

A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53 Two-Dimensional Analyses of EDR In-Formation: Volume 2, Issue 1, Page 12

Braking Efficiencies of Motorcycles by Experienced Riders in Hard Breaking Situations: Volume 4, Issue 2, Page 54

Busses (and school busses)

Cable options for the “CDR System Handyman”: Volume 3, Issue 1, Page 82

Compartmentalization Compromised: The Issue of School Bus Passenger Safety: Volume 2, Issue 1, Page 28

ACM Reprogramming: Volume 4, Issue 1, Page 18

Aerodynamics Quantifying the Aerodynamic Forces Acting on a Vehicle and Projectile: Volume 2, Issue 2, Page 120

Book reviews

School Bus Rollovers and Passenger Compartment Ejection: Solving the Puzzle Using Videoanlytics: Volume 3, Issue 2, Page 66 Bus Braking Tests: With and Without ABS: Volume 3, Issue 2, Page 70

Case Problems

Book Reviews: Volume 2, Issue 1, Page 82

Crash Data Case Study: Volume 1, Issue 1, Page 28 (Solution on page 97) Crash Data Case Study (Follow-up from Issue 1): Volume 1, Issue 2, page 40

Book Reviews: Volume 3, Issue 1, Page 60

Braking The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and other Factors: Volume 1, Issue 1, page 9 Deceleration Rates of Modern Passenger Vehicles During Straight Line Braking and Yaw Events: Volume 1, Issue 2, Page 20 Identification of Unusual Tire Marks at the Scene of a Motor Vehicle Collision: Volume 1, Issue 2, Page 30

2 in 3 out Case Study: Volume 1, Issue 2, Page 90 (Solution on page 102) Two Crash Data Case Problems: Volume 2, Issue 1, Page 24 (Solution on page 61) Secondary Contact Case Problem: Volume 2, Issue 2, Page 58 (Solution on page 150)

Commercial vehicles Contribution of a Laterally Displaced Vehicle to the Post-Impact Deceleration of a Heavy Truck: Volume 1, Issue 2, Page 96

Application of Drag Coefficients to ABS Related Sideslip: Volume 2, Issue 2, Page 46 Effects of Sample Rates on Accelerometer Based Skid Testing and Unit Comparison: Volume 2, Issue 2, Pg 66 108 Collision

www.collisionpublishing.com

Signal Processing Applied to Vehicle Speed Measurement and Recording: Volume 4, Issue 1, Page 26 Testing the Last Stop Record in the Mercedes MBE 4000: Volume 4, Issue 2, Page 74

EEPROMs Between Modules: Volume 3, Issue 1, Page 28

Ford A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53

Commercial Vehicle Dynamics For Collision Reconstruction: Volume 4, Issue 2, Page 106

Dynamic Accuracy of Powertrain Control Module (PCM) Event Data Recorders During ABS Braking: Volume 3, Issue 1, Page 44

Crash Testing Carrying out a High Speed Crash Test for the Dutch Police: Volume 2, Issue 1, Page 52

The Accuracy of Speed Recorded by a Ford PCM and the Effects of Brake, Yaw and other Factors: Volume 3, Issue 1, Page 48

The Accuracy of General Motors Event Data Recorders in NHTSA Crash Tests: Volume 2, Issue 1, Page 70

Comparing Different Sources of CDR Data to “Real World” Crashes: Volume 3, Issue 1, Page 88

ARC-CSI Crash Conference – Crash Test Data Summary: Volume 2, Issue 2, Page 6 Effects of Sample Rates on Accelerometer Based Skid Testing and Unit Comparison: Volume 2, Issue 2, Pg 66

Using Ford PCM Data to Evaluate Deceleration Rates, Brake Time and Impact Speeds: Volume 4, Issue 1, Page 74

Getting Published

Validating Speed Analysis Calculations with Crash Test Data: Volume 2, Issue 2, Page 70 European Accident Reconstruction by the Visual Comparison with Crash Tests: Volume 2, Issue 2, Pg 92

Getting Into Print as an Accident Reconstructionist: Volume 1, Issue 2, Page 56

GM Analysis of the GM Sensing and Diagnostic Module in 260 Degree Linear Momentum Collisions: Volume 1, Issue 1, Page 17

Implications of Symmetric Sine-Based Collision Pulse Models on Force-Deflection Characteristics: Volume 2, Issue 2, Page 104

A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53

An Alternative Formulation for Symmetric Sine Based Collision Pulse Models: Volume 3, Issue 1, Page 34

The Accuracy of General Motors Event Data Recorders in NHTSA Crash Tests: Volume 2, Issue 1, Page 70

Crush Damage-Based Collision Severity Reconstruction Technique: Volume 2, Issue 1, Page 34

General Motors Data Recording: A Visual Approach to the Logic Functions: Volume 2, Issue 2, Page 18

When Measuring Vehicle Crush… Find the Method that Works Best for You: Volume 2, Issue 2, Page 78

Average Daily Ignition Cycles in SDM Equipped, GM Vehicle: Volume 2, Issue 2, Page 42

Vehicle Crush Measurement: Helpful for extracting Key Details of Crash Scenes: Volume 2, Issue 2, Page 98 Implications of Symmetric Sine-Based Collision Pulse Models on Force-Deflection Characteristics: Volume 2, Issue 2, Page 104

Comparing Different Sources of CDR Data to “Real World” Crashes: Volume 3, Issue 1, Page 88

An Alternative Formulation for Symmetric Sine Based Collision Pulse Models: Volume 3, Issue 1, Page 34 Single Point Crush Variation: Volume 3, Issue 1, Page 94

Extrication Automobile Extrication for the Reconstructionist: Volume 4, Issue 2, Page 82

EDR Durability EDR Durability: Volume 2, Issue 1, Page 64 Vehicle Fires and Airbag Modules: Volume 3, Issue 1, Page 18 Getting Data from Destroyed SDMs: Transferring

The Latest CDR System Data From GM Vehicles: Volume 4, Issue 2, Page 38

GPS The Future of Accident Reconstruction: Volume 2, Issue 1, Page 62 Using GPS Based Data Acquisition in Forensic Accident Reconstruction: Volume 2, Issue 2, Page 114

Human Factors Alcohol and Vehicle Collisions - Correlation or Cause?: Volume 4, Issue 1, Page 80 Death Investigations and Their Psychological Effect on Police Officers: Volume 4, Issue 2, Page 64 Perception-Reaction Time: Is Olson (& Sivak) All You Need to Know?: Volume 4, Issue 2, Page 88

Ignition Cycles

www.collisionpublishing.com

Collision 109

Average Daily Ignition Cycles in SDM Equipped, GM Vehicle: Volume 2, Issue 2, Page 42

Legal Issues CDR Presentation and Validation in Legal Proceedings: Volume 1, Issue 1, Page 43 Rational Legislative and Organizational Policy for Automotive Event Data Recorders: Volume 1, Issue 1, Page 56 CDR Evidence: Frequently Asked Questions: Volume 4, Issue 1, Page 62

Brake Time and Impact Speeds: Volume 4, Issue 1, Page 74

PDOF PDOF: Principal Direction of Force: Volume 1, Issue 2, Page 12

Pedestrians ight Time Pedestrian Collision Reconstruction Factors: Volume 2, Issue 2, Page 82

Photography Pictometry in Crash Investigation: Volume 1, Issue 2, Page 44

Measurement

Making History: PhotoModeler Software Helps Knott Laboratory Reverse-Engineer the Past: Volume 1, Issue 2, Page 50

Comparison of Vehicle Measurement Techniques: Volume 4, Issue 2, Page 96

Momentum

Close Range Photogrammetry: Volume 2, Issue 1, Page 20

Analysis of the GM Sensing and Diagnostic Module in 260 Degree Linear Momentum Collisions: Volume 1, Issue 1, Page 17

Close Range Photogrammetry as a Routine Crash Reconstruction Tool Within the Florida Highway Patrol: Volume 3, Issue 2, Page 16

2 in 3 out Case Study: Volume 1, Issue 2, Page 90 (Solution on page 102) Analysis of Collisions: Point Mass Mechanics and Planar Impact Mechanics: Volume 2, Issue 1, Page 38

Forensic Photography and Crash Reconstruction, Part I: The Professional Amateur Expert Witness Photographer: Volume 3, Issue 2, Page 62

Use of the Combined Velocity Equation in Cases Involving Post-Collision Movement: Volume 2, Issue 2, Page 52

Photo Rectification Plays an Important Role for Determining Fault in a Two Vechile Crash Volume 4, Issue 1, Page 14

Centrifugal Force: Is It Real?: Volume 3, Issue 2, Page 48

Forensic Photography and Crash Reconstruction Part II: Solutions to Common Problems: Volume 4, Issue 1, Page 88

Momentum - Vectoring a New Approach: Volume 4, Issue 2, Page 30

Motorcycles Motorcycle Crash Investigation: Volume 1, Issue 2, Page 32 Ranges of Safety Provided by Safety Technologies Used for Reducing Motorcycle Crashes, Fatalities, Injury, and Loss: Volume 4, Issue 1, Page 44 Honda Gold Wing Motorcycle: Linked Brakes and Their Performance: Volume 4, Issue 2, Page 46 Braking Efficiencies of Motorcycles by Experienced Riders in Hard Breaking Situations: Volume 4, Issue 2, Page 54

Estimation of Vehicle Speed and Trajectory Based on Video From A Vehicle-Mounted Camera: Volume 4, Issue 2 Page 18

RCM A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53 ACM Reprogramming: Volume 4, Issue 1, Page 18

Rollovers Vehicle Dynamic Characteristics of SUVs in On-Road, Un-tripped Rollover Accidents: Volume 1, Issue 2, Page 62

PCM

Reconstruction & Analysis of Steering-Induced, OnRoad, Un-tripped SUV Rollovers (Part 1): Volume 2, Issue 1, Page 88

Dynamic Accuracy of Power train Control Module (PCM) Event Data Recorders during ABS Braking: Volume 3, Issue 1, Page 44

Reconstruction & Analysis of Steering-Induced, OnRoad, Un-tripped SUV Rollovers (Part 2): Volume 2, Issue 2, Page 124

The Accuracy of Speed Recorded by a Ford PCM and the Effects of Brake, Yaw and other Factors: Volume 3, Issue 1, Page 48

Using Ford PCM Data to Evaluate Deceleration Rates, 110 Collision

SDM

www.collisionpublishing.com

Reconstruction: Volume 4, Issue 2, Page 106 The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and other Factors: Volume 1, Issue 1, Page 9 Two-Dimensional Analyses of EDR In-Formation: Volume 2, Issue 1, Page 12 Detailed Comparison of Vehicle Speed and the Speed Recorded by an SDM, Volume 2, Issue 2, Page 32 Average Daily Ignition Cycles in SDM Equipped, GM Vehicle: Volume 2, Issue 2, Page 42 Getting Data from Destroyed SDMs: Transferring EEPROMs Between Modules: Volume 3, Issue 1, Page 28

Visibility Night Time Pedestrian Collision Reconstruction Factors: Volume 2, Issue 2, Page 82

Yaw The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and other Factors: Volume 1, Issue 1, Page 9 Deceleration Rates of Modern Passenger Vehicles During Straight Line Braking and Yaw Events: Volume 1, Issue 2, Page 20

Cable options for the “CDR System Handyman”: Volume 3, Issue 1, Page 82 ACM Reprogramming: Volume 4, Issue 1, Page 18 The Latest CDR System Data From GM Vehicles: Volume 4, Issue 2, Page 38

Simulations Simulations 101: Anatomy of a Simulation: Volume 1, Issue 2, Page 36 Making History: PhotoModeler Software Helps Knott Laboratory Reverse-Engineer the Past: Volume 1, Issue 2, Page 50

Snowmobiles Snowmobile Data: Volume 2, Issue 2, Page 74

Speed Vehicle Speed Sensor Calibration: Volume 3, Issue 2, Page 22 Calculating Speed from Skidmarks: Volume 4, Issue 1, Page 40 Using Ford PCM Data to Evaluate Deceleration Rates, Brake Time and Impact Speeds: Volume 4, Issue 1, Page 74 Estimation of Vehicle Speed and Trajectory Based on Video From A Vehicle-Mounted Camera: Volume 4, Issue 2 Page 18 "What is 30?": Volume 4, Issue 2, Page 26

Tire marks Identification of Unusual Tire Marks at the Scene of a Motor Vehicle Collision: Volume 1, Issue 2, Page 30 Calculating Speed from Skidmarks: Volume 4, Issue 1, Page 40

Vechile Dynamics The Mathematics of Turns, Evasive Maneuvers, Lane Changes, and Passing: Volume 4, Issue 1, Page 66 Commercial Vehicle Dynamics For Collision www.collisionpublishing.com

Collision 111

The most comprehensive training summit for crash data retrieval. This Summit features industry experts speaking on various technical topics as they relate to CDR. The annual CDR Summit is the perfect time to broaden and refine your knowledge of CDR and network with other CDR experts.

3-D Simulation & ViSualization Since 1993

Expert AutoStats® Expert AutoStats® is a computer program containing over 40,000 vehicles cars, vans, utility vehicles, and light pickups. 1945-2010 model years are represented.

This program can be used alone or with our Expert Qwic Calcs® and Expert VIN DeCoder® programs. Also accessible from within REC-TEC.

4N6XPRT StifCalcs® 4N6XPRT StifCalcs puts the NHTSA Crash Test database on YOUR 32 bit MS-Windows computer PLUS calculates A-B-G values and Test Specific Crush Factors based on the NHTSA test data, with no need for you to get on the internet, all for the price of only $570.00*! Can you do this yourself “for free”?? Only if you value YOUR time at $0.00!!

(Laptop & Desktop IBM Compatible)

Enter:

Manufacturer and Year

Select:

Model from pop-up window

Output:

Wheelbase Overall Length Height Wt. Distrib

Curb Weight Width Drive Wheels Front/Rear Track

Mid-60's to present output also includes (when available): Front Overhang Rear Overhang Bumper Heights Hood Height Turning circle Wheel radius Bumper-to-Hood Bumper-to-Window

HVE Technology Timeline – Key DaTes 1996

EDC introduces HVE Version 1.0 and several integrated simulation modules (e.g., EDSMAC, EDVSM, EDSVS) to perform real-time 3-D vehicle crash simulation and visualization for the first time.

1998

EDC introduces EDSMAC4, an extended version of EDSMAC that simulates in a single run an entire crash sequence involving any number and any type of vehicles.

1999

EDC introduces SIMON ®, the first fully 3-D HVE-compatible simulation that visualizes in a single run any number and any type of vehicles with suspensions, steering systems, braking systems and drivetrains.

2004

EDC introduces DyMESH ®, the first fully 3-D collision simulation and visualization model integrated within HVE.

2011

EDC introduces HVE DamageStudio®, the first tool to allow users to correlate 3-D collision damage directly with the kinetics (force magnitude and direction), delta-V, acceleration and other important collision parameters.

Expert AutoStats® is currently owned by over 660 private individuals and 270 Law Enforcement agencies in the U.S.A., Canada, and South America. Additional information, brochure, and order from can be downloaded from:

Search for vehicles by entering Year, Make, and Model, or by any combination of: Length, Wheelbase, Weight, Body Style, Make, Model, and Impact location Print out data and stiffness for single tests, or a Test Summary Stiffness Report when more than one test meets your search criteria For more information, program order form, and sample printouts please visit our web site at http://www.4n6xprt.com. You may also call us at (619) 464-3478 M-F, 9a-5p (PST), if you have specific questions.

www.4n6xprt.com/4n6sc.htm

www.4n6xprt.com/4n6as.htm

PROGRAM ORDER FORM (Please Print) Contact Name: ________________________________________________ Company: ____________________________________________________ Street: ______________________________________________________ City:____________________ State:____ Zip:__ __ Country: __________ Phone: (_____) _______________ Fax: (_____) ___________________ E-Mail: ______________________________________________________ Expert AutoStats® 4N6XPRT BioMeknx™ Expert Qwic Calcs® 4N6XPRT Ped & Bike Calcs® 4N6XPRT StifCalcs® Expert VIN DeCoder® (pkg) Expert TireStuf® Order Processing

- C heck = $5.00 / C redit C ard = $10.00 / G ovt. P .O . = $15.00 N otarized Affidavit R equirement $25.00 per required N otarized Signature

www.edccorp.com/HVEtechnology

= ________ = ________ = ________ = ________ = ________ = ________ = ________

= _______ = _______

Q Deliver via electronic download (Email address Required) = 0.00 Q Ship on USB - $35.00 per disk per program = ______ California Sales Tax Enclosed is:

For the complete HVE Technology Timeline visit:

- $ 595.00 ea.

- $ 495.00 ea.

- $ 275.00 ea.

- $ 375.00 ea.

- $ 570.00 ea.

- $ 525.00 ea.

- $ 85.00 ea.

- 9.50%

TOTAL (U.S. Dollars)

= ________

= ________

V isa ___ M asterC ard ___ Am. Ex. ___ E xp ____/____ - C heck ___ - G vt PO ___

Card Number: _______________________________________________ Name on Card: _______________________________________________ Signature: ________________________________________________ Please Make Checks*/Purchase Orders Payable to:

4N6XPRT Systems®

8387 University Ave - La Mesa, CA 91941-3842 - U.S.A. FAX: (619) 464-2206 Phone: (619) 464-3478 Web: http://www.4n6xprt.com

Engineering Dynamics Corporation 8625 SW Cascade Ave., Suite 200 Beaverton, OR 97008 USA (503) 644-4500 • www.edccorp.com COL-SP11

Knowledge = Power

Checks *MUST* be drawn on a U.S. bank. Orders are shipped within 10 working days of receipt.

Prices subject to change without notice.

Multiple orders and Package discounts available. Please call for details.