Volume 1, Issue 1

The International Compendium for Crash Research

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Volume 1 Issue 1

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Collision: The International Compendium for Crash Research

ollision C Accuracy of Speed Recorded by an SDM & the Effects of Brake & Yaw Events Analysis of the GM Sensing & Diagnostic Module in 360 Degree Linear Momentum Collisions: Real Case Analysis CDR Data Presentation & Validation in Legal Proceedings

Case Study:

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Implementing Policy for CDR

Motorcycle Collinear Collisions Involving Motor Vehicles Equipped with EDRs

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Event Calendar

Organization News

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Incorporating CDR Services in an Existing Forensic Practice

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Volume 1, Issue 1 - June 2006

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A Review of Various ACM Module Types & Data Recorded

Premier Issue

Includes CD 2006 CDR User’s Conference

www.CollisionPublishing.com

Collision Safety Institute

Special Offer

The ARC Network is pleased to offer a FREE Collision Safety Institute CDR training course or a cash rebate when you purchase a new Vetronix CDR System through the ARC Network. Also included with your purchase is a FREE one-year membership to the ARC Network. at

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CDR

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CDR Technician and Data Analyst Training series

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Crush Computer not included

The Vetronix CDR System has fast become an indispensible tool of a complete crash reconstruction program. Police agencies, private reconstructionists, engineers, government agencies and other safety researchers have come to the realization that the data stored in the air bag control module and accessible using the Vetronix CDR System is an invaluable part of a complete and thorough crash reconstruction.

CDR System

“Whether for trial, research,

Computer

Air Bag Control Module

Collision Trauma Biomechanics

Pedestrian & Bicycle Reconstruction of Pedestrian or Bicyclist Involved Collisions

Human Factors Human Factors: Understanding Driver Response

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(not included)

Biomechanics

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or any other crash related safety program, the CDR System has become an integral reconstruction tool”

Damage And Energy Applications for Collision Reconstruction (CRUSH)

For complete information please contact the ARC Network Toll Free: (866) 223-4984 Email: arc@accidentreconstruction.com

www.CollisionSafety.net

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www.cdr-system.com

The Collision Safety Institute (CSI) is an independent traffic collision research, training and consulting organization. CSI’s mission is to provide state-of-the-art training and technology transfer to both public and private entities involved in the analysis and evaluation of motor vehicle collisions, provide technical support to professional associations and organizations in their training efforts and conduct testing and research on surface vehicle collision topics and related technology.

Contents june 2006

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of interest From the Editor

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Calendar of Events

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On The Cover

Organization News

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Letter From NAPARS

Photo By: Scott Baker Taken at the Bremerton Race Track in Washington at the 2002 ARCCSI Crash Conference. This was approximately a 52 MPH collision.

Trivia: This photo was used as the framework for the ARC-CSI logo.

features The Accuracy of Speed Recorded by an SDM and the Effects of Brake, YAW and other Factors

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Analysis of the GM Sensing and Diagnostic Module in 360 Degree Linear Momentum Collisions

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CDR Presentation and Validation in Legal Proceedings

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A Review of Various ACM Module Types and Data Recorded

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Rational Legislative and Organizational Policy for Automotive Event Data Recorders

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Practical Ascpects of CDR Using the Vetronix System

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Motorcycle Collinear Collisions Involving Motor Vehicles Equipped with EDRs

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Crash Data Case Study

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Case Study Solution

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case study 28

from the editor If you asked me a year ago, the last thing I thought I’d be doing is being involved in the development of a new print magazine but here we are, Volume 1, Issue 1 of Collision.

So, how do we find ourselves here?

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Well, about a year ago the Yahoo CDR User’s Group, the ARC Network, Collision Safety Institute, Vetronix and NAPARS (the National Association of Professional Accident Reconstruction Specialists) began planning and developing the “CDR User’s Group Conference” which was to be held (and was held) in Dallas in February 2006.

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Several things stood out about that conference. First, we distributed - at that conference - a CD to those who attended including all the papers and presentations made at that Conference: a standard the ARC-CSI crash test team has upheld since 2002 at conferences throughout the US and Canada.

Next, it stands out as an almost one of a kind meeting in which industry, government, and researchers from public and private agencies came together to share information about the “Crash Data Retrieval” technology in a new and exciting way.

But then came the follow up.

In the planning stages, one of the vital and important members of the Conference planning committee was and continues to be NAPARS and part of the plan developed with NAPARS was to arrange for the papers and presentations from this conference to be published in a print format journal. As things developed, that wasn’t to be. Still in all, we’d assured the Conference authors and speakers that we would make their work available outside the conference, that we would publish their work beyond the scope of the Conference. So, as a function of that original print opportunity falling apart, we decided that the best way to keep faith with the authors and presenters and distribute the information from this Conference was to develop Collision. And so, here we are.

Now, where are we going? Collision will be published twice a year. As the new, premier journal of its kind within the industry, Collision will quickly become THE resource for timely and current research and information on crash analysis and investigation on a number of levels. This is the first publication of its kind, featuring conference proceedings, articles of interest, crash test data, industry news and research. Included with every issue is a bonus CD containing all papers and presentations in electronic PDF format along with the supporting data. While we will publish the papers and research from these conferences we’re also including additional content including case studies, articles of interest, a calendar of events, messages and postings from organizations.

The next issue? After the ARC-CSI Conference in Las Vegas in June, the next issue will recount the research, papers

and presentations from that conference in addition to the normal features. After that, we go to Houston, Texas in 2007 for the second CDR User’s Conference and will offer meaningful, peer reviewed papers from that conference as well.

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Who’ll be involved? The NAPARS Board of Directors voted unanimously to approve an exclusive agreement with

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Collision Publishing to make NAPARS the Premier Industry Partner to this new publication. As a result, NAPARS is offering a complementary subscription to all of its members who are in good standing and will participate directly in the development of the content of the magazine. No other publication enjoys this type of support from NAPARS. And then there’s YOU.

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You can contribute. We want to hear from you about what you like, what you don’t like, what you want to see in (c

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Collision. Contact me directly at sbaker@crashdatagroup.com and give us feedback, good or bad. Then check back here for updates, changes and important industry announcements because this will be THE resource, the place for Collision information, research, and other information.

Scott B. Baker Managing Editor www.crashdatagroup.com Collision

Bonus DATA Your digital copy of Collision Magazine Volume 1, Issue 1 includes the hard-copy presentations from the 2006 CDR Summit.

ADVERTISING

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Collision Staff

Adverstising Rates, Subscriptions & In-

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Content Advisory Committee

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W. R. Rusty Haight Brad Muir Tom Szabo Judson Welcher John Meserve

Collision Safety Institute Biomechanical Research & Testing Biomechanical Research & Testing President, NAPARS

COLLISION is published semi-annually by Collision Publishing LLC. Copyright © 2006, Collision Publishing LLC. The opinions and conclusions expressed in this publication and attached data disk in articles attributed to specific authors are the opinions and conclusions of the authors noted and not necessarily the editorial staff or reviewers of those documents. Really, facts belong to everybody, any other are 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 118 Lake Street South Suite G, Kirkland, WA 98033. By sending an email to any or 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. (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. All “Letters to the Editor” should be emailed to Collision Publishing. All rights in letters sent to COLLISION will be treated as unconditionally assigned for publication and copyright purposes and subject to COLLISION’s unrestricted right to edit.

Advertise

on the ARC Network Advertise on the #1 web site for accident reconstruction and traffic accident investigation - The ARC Network. For complete information visit:

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DIGITAL AD REQUIREMENTS: Digital data is required for all ad submissions. Preferred format is EPS and PDF. Files should be press optimized, converted to CMYK, and have all fonts embedded. Publisher shall have no obligation or liability to Advertiser of any kind (including, without limitation, the obligation to offer Advertiser makegoods or any other form of compensation) if an as is supplied to Publisher by Advertiser in any format other than PDF. We will also accept AI, PSD, TIFF, and DOC file types.

Please be sure to include a copy of all fonts used in your art work. Publisher will not supply a faxed or soft proof for Advertiser-supplied files. Advertiser is solely responsible for preflighting and proofing all advertisements prior to submission to Publisher. If Publisher detects an error before going to press, Publisher will make a reasonable effort to contact Advertiser to give Advertiser an opportunity to correct and resubmit Advertiser’s file before publication.

All advertisement are 4-color and professionally printed using a digital press.

For complete and up-to-date information regarding advertising in Collision, please refer to our web site: www.collisionmagazine.com

SUBSCRIPTIONS Annual Subscription Rates United States: $139.00 Annual Subscription Rates International: $149.00

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Editor Advertising Account Manager

FORMAT Full Page 1/2 Page 1/3 Page Back Cover Inside Back Cover Inside Front Cover 2-Page Spread

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sbaker@crashdatagroup.com

Sean Haight Tonya Baker

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Publisher, Managing Editor

Scott Baker

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https://www.thecrashhub.com/join

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ARC-CSI Crash Conference CDs

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Crash Data Group Inc PO Box 892885 Temecula, CA 92589 Toll Free: 800-280-7940 Email: sbaker@crashdatagroup.com Web: www.collisionmagazine.com

Past ARC-CSI Crash Conference CDs are available for purchase at www.CrashDataGroup.com Collision

Calendar

conferences, training, and meetings

catair

caars

Jan/Feb 2007 CDR User’s Conference Texas

Oct 30, 06 CDR Technician Oct 31-Nov 2 CDR Analyst Edmonton, AB (with Collision Safety Inst.)

July 2006 CAARS: Restraints, Airbags, & Child Restraints Northern California

Nov 6, 06 CDR Technician Nov 7-9 CDR Analyst Calgary, AB (with Collision Safety Inst.)

August 2006 CAARS: Restraints, Airbags, & Child Restraints Southern California

Sep 9, 2006 Bloomington, IL Sep 17, 2006 Houston, TX

engineering dynamics

collision safety institute

November 6-10, 2006 EDC Reconstruction Coral Gables, Florida

November 16-18, 2006 CAARS: Fall Conference – Crash Reconstruction, Start to Finish

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June 2007 ARC-CSI Crash Conference Las Vegas, Nevada (c )

actar exam dates

CDR Technician July 11, 2006 CDR Analyst July 12-14, 2006 Overland Park, Kansas CDR Technician July 24, 2006 CDR Analyst July 25-27, 2006 Toronto, Ontario

February 26-March 2, 2007 2007 HVE Forum San Antonio, Texas

CDR Technician Sept. 11, 2006 CDR Analyst Sept.12-14, 2006 Dayton, Ohio

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CDR Technician Oct. 30, 2006 CDR Analyst Oct. 31-Nov. 2, 2006 Edmonton, AB (with CATAIR Prairie)

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CDR Technician Oct. 17, 2006 CDR Analyst Oct. 18-20, 2006 Colts Neck, New Jersey

CDR Technician Nov. 6, 2006 CDR Analyst Nov. 7-9 Calgary, AB (with CATAIR Prairie)

Collision

organizations

the cad zone

July 17-21, 2006 MapScenes System Upgrade Training Sherman, Texas

September 17-21, 2006 TAARS Expo 2006 Houston, Texas

July 17, 2006 Basic/ Advanced CrashZone & CrimeZone Canton, Ohio

July 31, 2006 Basic CrashZone/CrimeZone Diag.

Ft. Worth, Texas

sae August 2-4, 2006 Commercial Vehicle Braking System

August 3, 2006 Advanced CrashZone/CrimeZone Diagramming Ft. Worth, Texas

August 24-25, 2006 Vehicle Accident Reconstruction Methods

August 21, 2006 Basic CrashZone/CrimeZone Riverside, CA August 24, 2006 Advanced CrashZone/CrimeZone Riverside, CA

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September 11, 2006 CrashZone 2D/3D Collision Mapping Forsythe, Georgia ra

October 30, 2006 CrashZone 2D/3D Collision Mapping Forsythe, Georgia

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If you would like to list an event in future issues, please send an email with complete information to editor@collisionpublishing.com

State College, PA

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Bloomington, Illinois

July 19 2006 Basic Crash/Crime Zone Course Henderson, Nevada

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September 4-5, 2006 IATAI sponsored MapScenes 3D

September 26-28, 2006 PA State Police Reconstruction Seminar

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August 7-11, 2006 Forensic Mapping Training Kansas City, Missouri

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Organization News ra

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ARC Network - www.accidentreconstruction.com - Founded in 1998, the ARC Network is the largest Internet portal web site for the industry of accident reconstruction and traffic accident investigation. This organization provides resources and information for all areas of accident reconstruction and traffic accident investigation including research, news, expert discussion, events, products and services, expert witness directory, book store, education services directory, police department directory and a member’s only section that provide valuable online databases and tools to assist in daily accident reconstruction requirements.

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

CA2RS - www.ca2rs.com - CA2RS was created to provide accident reconstruction training and resources to its members. There is a growng need for more local resources in the accident reconstruction field. This organization has grown to over 260 paid members and are always looking for ways to strengthen and increase their membership.

CATAIR - www.catair.net - The Canadian Association of Technical Accident Investigators and Reconstructionists (CATAIR) was founded in 1984 to meet the growing demand for a professional organization that subscribed to a code of professional conduct. CATAIR membership is open to individuals involved in all aspects of road safety. Current membership is in excess of 250. presently, our membership is comprised of active and retired police officers, professional engineers, automotive engineers, engineering technologists, private consultants and representatives from the insurance industry.

FARO - FARO, officially known as Forensic Accident Reconstructionists of Oregon, was chartered in June 1994 under the laws of the State of Oregon. Officially designated as a non-profit, mutual benefit corporation, FARO exists as a voluntary professional association of individuals who practice forensic reconstruction in Oregon.

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IAARS - www.iaars.org - The International Association of Accident Reconstruction Specialists was started in 1980 as a training and networking resource for members. It is believed we are the oldest such crash reconstruction organization. Our membership consists of Law Enforcement as well as Engineers and PhD’s. We have members from 38 states as well as Canada, England, Singapore, Spain and West Australia. Our association is a little different from many others in that we have a peer review process for membership. This peer review is a specific area of judicial consideration when admitting an expert opinion in court. The annual seminars, held in different locations nationwide, not only provide instruction on specific topics by experts in the field, they provide face-to-face discussions on how other people approach reconstructing a crash. The old saying “two heads are better than one” is definitely true in accident reconstruction. The next seminar will be the Big Event in Houston, TX in September 2006.

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IATAI - www.iatai.org - The Illinois Association of Technical Accident Investigators was born after several members of the Illinois State Police completed their training in traffic crash reconstruction. They saw the need for a way to share information, experiences and grow as Accident Investigators. These founding members set four goals for the organization; 1. To provide professional standards for members investigating accidents; 2. To promote the continued expansion of members knowledge in the area of technical accident investigation.; 3. To promote Traffic Safety through accident investigations; and 4. To promote improved capability of each agency through training and idea exchange. Since 1986, IATAI has held annual training conferences throughout the State of Illinois. These conferences serve to bring valuable training from across the country into Illinois. Our membership reaches out to 26 states in both the public and private sector.

MATAI - www.mdatai.org - MATAI continues to be innovative and willing to meet the needs of its membership. Over the years, MATAI has grown into a internationally renowned organization. MATAI has sponsored or co-sponsored numerous conferences that have been attended by fellow investigators from around the world. These conferences have included relevant and at times, spectacular test collisions involving cars, trucks, motorcycles, pedestrians, bicycles, and even a Metrobus.

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MATAI - www.matai.org - Founded in 1988, the Midwest Association of Technical Accident Investigators (MATAI) was formed to provide a professional affiliation for individuals who have a primary interest in the technical aspects of motor vehicle traffic collisions. The Association is dedicated to the exchange of information and ideas to improve investigative techniques and procedures In addition, MATAI provides a communication source between other individuals and affiliations involved in this vital area of public safety. MATAl’s primary objective is to meet the needs of the people directly involved in the initial investigative process.

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NAPARS - www.napars.org - The National Association of Professional Accident Reconstruction Specialists is a non-profit organization whose members have joined together to share the challenge of dealing with the complex problems of accident reconstruction and to upgrade and ultimately professionalize the accident reconstruction field. NAPARS is open to all persons who are interested in the fields of traffic accident reconstruction and highway transportation safety. Present membership exceeds 1,100 and includes police officers, engineers, consultants and government safety personnel. NAPARS is also the Premier Industry Partner for Collision Magazine.

NATARI - www.natari.org - The National Association of Traffic Accident Reconstructionists and Investigators (NATARI) was established as a non-profit Pennsylvania corporation in 1984. The goal of NATARI is to provide a source of information to be shared among accident professionals on a national basis. This goal is reflected in the NATARI logo comprised of an outline of the nation, a broken wheel signifying a traffic collision and the words “to solve for safety”.

NJAAR - www.njaar.org - The New Jersey Association of Accident Reconstructionists started in 1991 as a dream of a few New Jersey police officers who wanted to create a network of individuals with interests in the field of accident reconstruction. Its membership has grown to encompass individuals from many states in all fields of accident reconstruction. We have a large membership base that includes many professionals not only from the police community, but the private sector as well.

NYSTARS - www.accidentreconstruction.com/nystars - The mission of NYSTARS is to organize into one body, professionals in the field of ground vehicle collision reconstruction and related activities, who support and maintain a high standard of ethics, integrity, credibility and honor in the field of collision reconstruction; to encourage training programs relating to motor vehicle collision investigation and reconstruction through research and communication of matters of mutual interest; to promote traffic safety and foster a spirit of brotherhood among the organization’s members.

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SATAI - www.satai.com - Established as a non-profit corporation in 1982, the Southwestern Association of Technical Accident Investigators, Inc. goal is to encourage and promulgate the development of professional technical accident investigation and highway safety; promote research and development of programs leading to better technical accident investigations; and to promote the development and dissemination of new knowledge in the fields of traffic safety, accident investigation and reconstruction. The Association is organized and operated for scientific and educational purposes.

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SOAR - www.accidentreconstruction.com/soar - An organization of accident reconstructionists dedicated to increasing knowledge, enhancing auto engineering, improving traffic safety and the free exchange of information. Membership is open to all people in all aspects of traffic transportation. Membership is comprised of active and retired police officers, professional engineers, automotive engineers and private consultants.

We have members throughout the world.

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TAARS - www.accidentreconstruction.com/taars - TAARS was organized in 1986 as an organization dedicated to advancing Research, Knowledge, Education and Safety in the field of accident reconstruction. TAARS is a broad based organization with members from many different fields, including law enforcement, private investigators, engineers and attorneys. TAARS has a current membership of over 220 members.

WATAI - www.accidentreconstruction.com/watai - WATAI was formed in 1979 and is the oldest of the technical accident investigation organizations in the United States. Twenty-five plus years since its inception WATAI remains true to its original mission; “to promote education and research in the field of accident investigation; to encourage interdisciplinary communication between the practitioners of accident investigation; and to cooperate and participate with other organizations dedicated to the science of accident investigations”. To that end WATAI sponsors semi-annual conferences. The Spring Conference usually takes place in May and the Fall Conference generally in the onth of October.

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National Association of Professional Accident Reconstruction Specialists, Inc. P. O. Box 65 Brandywine, Maryland, USA 20613-0065 (www.napars.org)

email: president@napars.org May 1, 2006 Mr. Scott Baker, Publisher Collision Publishing, Inc. 118 Lake Street South Suite G Kirkland, WA 98033

Dear Scott: Congratulations on the launch of Collision: The International Compendium for Crash Research!!

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The 1,100-member National Association of Professional Accident Reconstruction Specialists is proud to be the Premier Industry Partner to this wonderful publication. Collision will be the leader in the growth of accident reconstruction technology and communication and is a perfect match to NAPARS’ stated goal of advancing the body of knowledge of professional accident reconstruction in the 21st century.

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We look forward to a long and fulfilling relationship with Collision Publishing.

Sincerely, John H. Meserve President Collision

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The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and Other Factors

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-Timothy J. Reust, James M. Morgan Accident Science, Inc.

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A series of well-documented tests were conducted with various types of vehicles.

The testing included 12 different vehicles which included both front and rear wheel drives. The vehicle included passenger type, SUV, pickup and minivan. Some of the vehicles were equipped with the StabiliTrak electronic stability control system. All the testing was conducted on dry and level roadway surfaces. The tires of the vehicles were the original equipment size and were inflated to their recommended pressures. More than 80 instrumented tests were conducted for this research paper.

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available electronic data. The data can make a significant contribution to the engineering reconstruction of a vehicle accident. In some cases, the SDM data can provide information that traditional methods cannot.

This paper addresses the accuracy of the SDM-reported speed and the affects of brake, acceleration and yaw events.

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to evaluate the event.To date, only a limited study of the SDM-reported Many 1999 and newer speed accuracy has been reported by General Motor vehicles Lawrence. have an event data recorder (EDR) that can record data which NTRODUCTION includes pre-event speed. The EDR Late model General Motors is incorporated into the air bag system sensing and diagnostic module vehicles incorporate an (SDM). In this study, the accuracy of event data recorder with the vehicle-reported speed was tested the sensing and diagnostic module. during acceleration, coasting, braking The SDM can record pre-event and yaw at speeds between 1 to 90 speeds at one-second intervals for miles per hour. The accuracy was approximately five seconds preceding also tested during heavy acceleration, the event. The speed is in units of when an undersized spare tire was miles per hour and is recorded in 1 mounted on the drive axle and with mile per hour increments. Other tires having new and worn tire tread information recorded by the SDM depths. The vehicle-reported speed includes, engine RPM, throttle was compared to the speed measured percent and brake application. The by a calibrated GPS speed measuring recorded event can be triggered by system. The results showed that the air bag deployment or a deceleration. vehicle-reported speed matched well The vehicles used for this study were during acceleration and coasting, manufactured by General Motors and underestimated the speed during included both front wheel drive and braking and underestimated the speed rear wheel drive. This information during a yaw event. Information can be downloaded using the Vetronix downloaded from a SDM after Crash Data Retrieval (CDR) kit. an accident event can be used in conjunction with conventional The current trend in accident methods of accident reconstruction reconstruction is to make use of the BSTRACT

Some of the testing was done by slowly accelerating the vehicle up to speed, others with maximum acceleration and Collision

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NSTRUMENTATION

Vehicle speed was measured using a Racelogic VBox III GPS system .The VBox system has a speed accuracy of 0.063 mph averaged over four samples.

Collision 10

The instrumentation signals were ESULTS recorded by the VBox system. The vehicle-reported speed and additional The low acceleration tests engine and running gear data were provided data at speeds recorded as a snapshot through the between 1 to 76 miles per vehicles’ data link connector using hour and were combined together in a the Vetronix Tech 2. common graph. Based on this testing,

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The VBox speed was used to be the actual speed of the vehicle. After the recorded data was synchronized, the VBox speed and the snapshot speed from each test were evaluated.

The maximum acceleration tests were conducted at full throttle (100%) using the 2002 Chevrolet Camaro SS (rear drive with 5.7 liter LS1 engine) and the 2005 Pontiac Bonneville (front drive with 3.8 liter engine). The results show that speed errors are generally within the ±1.5 mile per hour except during initial takeoff and gear shifts. The graphs show the maximum error at each speed.

(Figures 4 and 5)

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The throttle sensor data from both the VBox data acquisition and the Tech 2 snapshot were used as the common trace to synchronize the two data sets together.

The coasting tests were conducted at speeds between 24 to 70 miles per hour and were combined in a common graph.

Based on this testing, the speed accuracy is +0.5 to -2.0 miles per hour during coasting. (Figure 3)

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the speed accuracy is ±1.5 mile per hour during low acceleration. (Figure 2)

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Each test produced two data sets: the instrumentation data (VBox) and the snapshot data (Tech 2). The data acquisition system of the VBox records 100 samples per second. The Tech 2 recorded a snapshot with approximately 3 to 10 samples per second

The maximum effort brake with ABS tests showed the vehicle-reported speed is underreported by approximately 8 to 18 percent at vehicle-reported speeds of 30 miles per hour and higher. The exception to this upper range was the pickup which had an error of 25 % which would occur briefly at approximately 0.28 seconds after brake application. A common trend

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A. 2001 Buick Regal B. 2002 Chevrolet Venture.

C. 2002 Chevrolet Camaro SS (manual transmission) D. 2004 Pontiac Bonneville E. 2005 GMC Yukon XL (with StabiliTrak) F. 2005 Chevrolet Suburban (with StabiliTrak) G. 2005 GMC Sierra Z71 H. 2005 Pontiac Bonneville I. 2005 Pontiac Bonneville J. 2005 Chevrolet Trailblazer K. 2005 Buick Le Sabre L. 2005 Cadillac Deville

The tests of the tires with worn and new tread depth were compared and used to show the variation in speed accuracy.

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The following vehicles were used during the testing:

For the brake tests and yaw tests a percent error was calculated between the VBox speed (actual speed) and the Tech 2 (vehicle-reported speed).

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and provided a relatively smooth data line. The difference between the VBox speeds at both the beginning and end of the step was used as the vehicle-reported speed error. (Figure 1)

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The brake testing speeds ranged from 15 to 90 miles per hour. The majority of the brake tests were conducted with the ABS brake system active, however some were with the system deactivated. Most of the brake tests were conducted with maximum brake application and some tests were done within the normal range of brake application. The yaw testing was conducted with and without brake application. A few tests were conducted with heavy acceleration induced wheel slip. Testing was also conducted with an undersized spare tire which was obtained from a vehicle and mounted to its drive axle.

The Racelogic (IMU) inertial measurement unit was used during the yaw tests to measure yaw rate and lateral acceleration. The VBox also recorded brake and throttle data. The initiation of brake pedal application was recorded by placing a tape switch on the surface of the brake pedal.

Throttle sensor position information was measured by placing wire taps onto the leads of the vehicle’s throttle position sensor

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some also included coasting and was done for the purpose of checking the accuracy of the vehicle-reported speed versus an instrumented speed.

For the low acceleration, coasting and tire tread depth tests, the vehicle-reported speed provided several data points at one speed and then would “step” to the next mile per hour value. During that time the VBox speed was constantly changing

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was seen at vehicle-reported speed below 20 miles per hour where the percent error would increase to a much higher value. (Figures 6, 7, 8, and 9) The lower level brake tests did not activate the ABS system but again showed an underreporting of the vehicle-reported speed. (Figures 10 and 11)

Yaw tests involving both steering and braking showed the vehicle-reported speed underreported by approximately 3 to 18 percent at speeds of 30 miles per hour and higher.

(Figures 17 and 18)

Speed Error Coasting

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(Figure 12)

of the 2002 Venture (front wheel drive) van resulted in an over reported vehiclereported speed. The standard size tire was a P215/70R15 with a measured circumference of 83.75 inches. The spare tire was a T125/70R15 with a measured circumference of 69.125 inches. The following graph shows the relationship to the speed values. (Figure 20)

The yaw tests when only steering was used showed the vehicle-reported speed underreported by approximately 2 to 7 percent at speeds of 30 miles per hour and higher. (Figures 15 and 16)

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The authors would like to thank Brad Muir for his help and encouragement and Loretta Reust

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During maximum brake application and when the ABS system is activated, the vehicle-reported speed is underreported by approximately 8 to 18 percent at speeds of 30 miles per hour and higher.

The exception was the pickup with an error of 25% which would occur briefly at approximately 0.28 seconds after brake application.

CKNOWLEDGMENTS

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A significant finding of this paper is showing how the ABS brake system operation will cause the vehicle-reported speed to be underreported and how that value is further affected as it reaches lower speeds.

Tread wear on a tire results in only a slight difference in the vehicle-reported speed error. The results show that with worn tires the vehicle-reported speeds are still within the ±1.5 mile per hour error range.

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Lawrence JM, Wilkinson CC, Heinrichs BE and Siegmund GP. “The accuracy of preDuring normal levels of brake application crash speed captured by event data where the ABS is not activated the recorders” SAE 2003-01-0889, 2003. ra

The speed sensor used for the Tech 2 speed is the VSS. The speed sensor used for the SDM downloaded speed is also the VSS. The synchronized data from the VBox and the Tech 2 show good timing agreement with each other in that they increase and decrease in unison.

Throughout this paper, the Tech 2 speed has been used interchangeably as the vehicle-reported speed.

An undersized spare tire mounted on a drive axle of a front wheel drive vehicle will cause the vehicle-reported speed to be over reported. A method to correct a downloaded speed is given in the discussion section of this paper.

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The vehicle-reported speed is calculated by the vehicle system using the input from the vehicle speed sensor (VSS) and programmed settings for pulses per distance and time. The VSS is located on the output shaft of the transmission.

The vehicle speed that is read by the VSS is a function of the wheel speed and may differ from the ground speed.

An example of differing speed is during a hard brake application and when the ABS brake system is activated causing the wheel speed will be less than the ground speed due to wheel slip.

Heavy acceleration induced wheel slip conditions will cause the vehicle-reported speed to be over reported.

Based on the tests conducted for this paper, the accuracy of the vehicle-reported speed during low acceleration is approximately ±1.5 mile per hour at speeds ranging from 1 to 76 miles per hour. During maximum acceleration at full throttle, the accuracy is approximately ±1.5 mile per hour except during initial takeoff and gear shifts at speeds ranging from 1 to 89 miles per hour. During coasting, the accuracy is approximately +0.5 to -2.0 miles per hour.

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ISCUSSION

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When a vehicle is in a yaw the vehiclereported speed will be underreported by approximately 2 to 7 % when only steering has been used and will be underreport by approximately 3 to 18 % when both steering and braking have been used at speeds of 30 miles per hour and higher.

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(Formula 1) Testing with tires having new and worn tire tread depths resulted in only a slight difference in the speed error. Worn tires will cause a slightly higher speed to be reported. The results show that the vehicle-reported speeds are still within the ±1.5 mile per hour error range. The new and worn tires were both Yokohama AVS ES100 P275/40ZR17 98W. The new tire had a tread depth of 10/32 inch and the worn tire had a tread depth of 2/32 inch. The results are shown near the speed of 45 miles per hour because tires are calibrated at that speed (see SAE J966 Recommended Practice). (Figure 21)

vehicle-reported speed will drop to zero approximately 0.72 to 1.07 seconds after brake application.

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C=circumference Download speed x ((Cspare + Cstock)/2)/ Cstock = correct speed

Graphs were prepared by combining the data from the VBox, Tech 2 and CDR download. The graphs show that there is a good agreement between the Tech 2 and CDR in terms of speed when a slight adjustment to the one second time intervals of the CDR data is made. Based on these tests, the Tech 2 speed appears to be a good representative of the SDM download speed. (Figures 22 and 23)

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The following formula was developed to correct speed downloaded from an SDM when an undersized tire has been found on the vehicle. (Formula 1)

vehicle-reported speed is underreported.

This trend is shown in (Figure 12).

During maximum and rapid brake application with a non-ABS system, the

Reust TJ. “The Accuracy of Speed Captured by Commercial Vehicle Event Data Recorders” SAE 2004-01-1199, 2004.

Reust TJ, Morgan JM. “Commercial Vehicle Event Data Recorders and the Effect of ABS Brakes During Maximum Brake Application” SAE 2006-01-1129, 2006.

2005 Pontiac Bonneville bon16 ABS Brake, 0.828g Brake Application at 24.73

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Collision 13

Low Level Deceleration vs % Error

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Figure 23 Collision 15

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Conferences & Training

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The ARC Network and Collision Safety Institute host the annual premier crash conference, the (c )

ARC-CSI Crash Conference

This conference is designed to be topical, timely and a lasting learning experience for all involved.

Every June in Las Vegas, NV you have the opportunity to witness live crash testing first hand, attend presentations by recognized leaders in their field, and leave the conference with crash data in hand including the video, photos, copies of presentations, and related documents.

There is no better opportunity for training. Anywhere.

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The ARC Network and Collision Safety Institute along with Vetronix, CDR Tool User’s Group and other sponsors host the newest conference and training opportunity, the

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Crash Data Retrieval User’s Conference (c

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This is a comprehensive conference held in Texas each February to publish CDR System related information in the form of peer-reviewed papers, data compendium and the like. It covers legal issues, current legislation, user applications and future updates and developments.

Visit us on the Web

www.crashconferences.com

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Analysis of the GM Sensing and Diagnostic Module in 360° Linear Momentum Collisions

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Event Data Recorder technology is not new, just as airbag technology is not new. Event Data Recorders, (E.D.R.s), have been around in automobiles since the early 1970’s1 . However they have become prevalent in automobiles since the early 1990’s.

only a limited number of vehicles which included pre-crash parameters.

Most of the vehicles in that original release included only delta-v data.

This data is often ignored and placed in a case file used only for the seatbelt information, if that. However, this information can be very valuable, especially in linear momentum analysis of collisions. The delta-v data gives us information recorded at the time of the crash. This information can validate a reconstruction to an amazing degree. What could be more compelling to a jury than to have the event data recorder on the vehicle involved in the collision agree with the results of the reconstruction.

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Event Data Recorder technology is becoming an ever present part of the reconstruction culture. The deltav data can be the most valuable data collected, especially in a linear momentum reconstruction.

The purpose of this paper is to discuss how to evaluate a reconstruction and compare what the reconstruction indicates to the instruments on board the crash vehicle, with a primary focus on the delta-v data. The paper will discuss the application of this valuable data and compare it to real world crashes reconstructed utilizing linear momentum techniques.

NTRODUCTION

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BSTRACT

- Weston H. Brown Scottsdale Police Department Vehicle Crimes and Reconstruction Unit

Vetronix is the first company to enter into a contract with automakers to create software and hardware capable of downloading this information available to the general public. The first release of the Vetronix Crash Data Retrieval software in 2000 included

Collision 17

occupants from a dangerous frontal The lateral delta-v is simply the force. Thus, the system is looking post-impact lateral velocity. at how severe the collision is in the Trigonometrically speaking: longitudinal axis of the vehicle. ∆v1 y = v3 sin(q ) Perhaps Rusty Haight puts it simplest, Equation 2.2 “The airbag deploys when there is a net negative acceleration observed relative to the x-axis.” 2

These formulae utilize common conventions for calculating speeds based on a linear momentum speed calculation.

The Greek symbol θ represents the departure angle of vehicle #1, v1 represents the pre-impact speed or velocity of vehicle #1, and v3 represents the post-impact velocity of vehicle #1. The vector diagram will show that by calculating the Principle Direction of Force, (P.D.O.F.) the same vector is calculated. This is simply an alternate method of going about finding the vector of the change in velocity along the longitudinal axis of the vehicle in a linear momentum analysis.

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The solution for vehicle #2 is only slightly more convoluted.

Vehicle #2 must now be broken down into its longitudinal and lateral velocities. Figure 2.3 shows a vector diagram including vehicle #1, which is in light gray. Based on Figure 2.3 diagram the following equation is found for calculating the expected delta v in the longitudinal axis of a given collision:

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What is important for analyzing this data is understanding the basics of how it is collected. The beauty of the delta-v data is that although calculated based on integrated acceleration data, this is the only data that is actually measured right at the Sensing and Diagnostic Module. All the precrash information is collected off of the Class 2 serial bus and the SDM is among the lowest priority for that information. But as previously stated, the delta-v information is calculated directly from instrumentation on board the SDM. One issue I have seen, especially among law enforcement, is understanding how to glean that information from your reconstruction to compare it to the data collected from the SDM. The data calculated from the reconstruction must be compared directly to the data recorded Figure 2.1 by the EDR and the two should not Looking at Figure 2.1 it is assumed the be combined to be compared. impact vector, v1, is placed along the What is deltaV, in SDM terms? x-axis. To calculate the longitudinal delta-v subtract the initial velocity, To understand what needs to be (v1), from the final longitudinal Trigonometrically calculated to compare with the velocity, (v3x).

SDM measurement it must first speaking: be understood what the SDM is ∆v1x = v3 cos(q ) − v1 calculating. Frontal airbag systems are only interested in protecting Equation 2.1

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This means that the common formula for delta-v is not comparable as it gives the total change in velocity, which includes the delta-v for both the x and y-axis. As in projectile motion, the motion of a vehicle can be broken down into the longitudinal and lateral or x and y (respectively) axis. To compute a comparable deltav, the longitudinal delta-v must be isolated. Figure 2.1 breaks down the vectors of vehicle one. v1 indicates the impact velocity, v3 indicates the post-impact velocity. The postimpact velocity is then broken down The difference in the two manners into its longitudinal, (x), and lateral, of arriving at the value for the longitudinal delta-v is simply that (y), axis. when you are working a D v1x momentum collision, the v3x PDOF may not be of interest to you and it creates one v 3 D v 1y additional area of calculations v3y θ which may add one or more additional areas in which v1 mistakes can easily be made.

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This is a leap forward in technology.

Previously we could only instrument crash test cars and this was limited to those with the resources to conduct crash tests. Most police agencies don’t have the resources to purchase the instrumentation, let alone the resources to conduct crash tests.

Furthermore, crash test are under very controlled circumstances and do not always represent real world conditions. E.D.R. data does have limitations and there can be significant uncertainty in the recorded data, but the information can be very valuable.

Collision 18

Equation 2.4 Once again, the answer can be derived by examining the PDOF, and this is a good cross check practice. This allows one more check in the analysis of the collision. It is clear that the change in velocity in the longitudinal axis may be arrived at by two means.

Approach and departure angles, trigonometrically or by the PDOF, trigonometrically.

In short what we are finding is the change in velocity in the longitudinal axis as a result of the collision, from first contact to maximum engagement.

The cases discussed in this paper are all actual cases investigated by the Scottsdale Police Department. The cases have been reconstructed by the author based on the Scottsdale Police

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∆v2 Lat = v4 sin( b )

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the vehicle was actually stopped by a curb strike, however, the curb strike did not create any notable damage to the vehicle. This allowed for a post impact speed of the Cavalier of 20 MPH. The F-150 was found to be 3. Case Studies traveling at 19 MPH post-impact based on the two locked front tires 3.1 2003 Chevrolet Cavalier vs. Ford and an acceleration factor of 0.42 based on 60% braking efficiency and a F150 distance from impact to uncontrolled The first case study involves a 2003 point of rest of 28 feet.

Chevrolet Cavalier, which turned left in front of a Ford F-150. The collision Figure 3.1.3 shows the deployment occurred on a dry asphalt roadway in download as a result of this collision. the nighttime hours. The roadway at There was also a non-deployment the collision scene was a 6-lane east/ file associated with this collision west roadway intersected by a 4-lane that occurred after the collision north south roadway. The module was approximately 2 seconds. As a result downloaded via a DLC connection of the two downloads a great deal of and the scene was measured utilizing information could be obtained. a Nikon Total Station, Model DTM521. The diagram and subsequent The non-deployment download measurements were arrived at indicated a speed of 21 MPH shortly utilizing TurboCad Computer after the deployment file was written.

Aided Drafting software. The crush This event was likely caused by the measurements were completed by the curb strike, as nothing else appeared to use of tapes using a linear perimeter have been struck. The 1 MPH speed measurement. Figure 3.1.1 shows the at the –1 position may be a result of approach angles which were arrived at data buffering, or the tire approaching by diagramming the vehicle damage. lock up, but the collision occurred Figure 3.1.2 shows the 2003 Cavalier prior to the tire actually locking up or the 1 MPH reading being taken as involved in this collision. the tire was being struck by the bullet PPost collision the two front tires vehicle. There were no signs of preon the F-150 were locked due to impact braking at the scene. damage and none of the tires on the Cavalier were locked due to damage. The Cavalier was placed as vehicle The “frame” of the Cavalier was #2 in this analysis. The approach o severely bent due to the collision angle, (ψ) was measured at 97 from and the Cavalier ended up rolling in the diagram in Figure 3.1.1. The a large circular motion around the departure angle, (φ) was measured o intersection as a result of the damage. at 19 . When placed in equation 2.3 As a result of this the Cavalier’s total the following results: distance to roll to a stop was 238 feet. ∆v 2 Long = v 4 cos( b ) − v 2 A rolling resistance of 0.06 was used as a simple drag factor to the point of ∆v 2 Long = -13 −13 MPH rest. This is assumed slightly low as (c

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Department files and compared to the relevant SDM files. Any criminal cases have been previously adjudicated.

Collision 19

Model DTM-521. The diagram and subsequent measurements were arrived at utilizing TurboCad Computer Aided Drafting software.

Figure 3.2.1 shows the 2000 Cavalier involved in this collision.

An analysis of the sensitivity of the approach and departure angles yielded little change in the results. I completed an analysis of the departure angle of the cavalier. The departure angle was varied by 10 degrees, with the original departure angle placed in the middle and also the approach angle.

The maximum delta-v was found to be –14 MPH at an approach angle of 102 degrees. The minimum deltav was found to be –13 MPH at an approach angle of 93 degrees. When the departure angle of the Cavalier was adjusted, the range fell entirely within the aforementioned values.

The most sensitivity was found when the departure angle of the Ford F-150 was varied. This led to a minimum delta-v of –12 MPH at 21 degrees and a maximum of –15 MPH at 30 degrees. The reconstruction delta-v falls right in the middle of this range.

Based on the reconstruction the post impact speeds of the vehicles were found to be as follows:

the reading was taken 1 second prior to AE. In fact this reading could be taken anywhere within the 1 second prior to AE or even in some rare instances after AE. Furthermore, the Brake On status indicated is a reading taken from the brake switch on the brake pedal and does not make any measurement of the amount of braking.

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The third case involves a 2004 Hummer H2, which collided in a “tbone” collision with a 2001 Pontiac Sunfire. The bullet vehicle in this case is the Hummer H2 which was traveling perpendicular to the Sunfire.

The collision occurred on a dry asphalt roadway in the nighttime hours. The roadway at the collision scene was a 2-lane east/west roadway intersected by a 4-lane north south roadway.

The intersection was controlled by a stop sign for east and west traffic.

The Sunfire module was downloaded via a desktop download and the H2 SDM was downloaded via a DLC connection. The scene was measured utilizing a Nikon Total Station, Model DTM-521. The diagram and subsequent measurements were arrived at utilizing TurboCad

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Figure 3.2.2 shows the download, which was completed via a bench top download after the SDM was removed from the vehicle. The 3.2 highest recorded delta-v is found to 2000 Chevrolet Cavalier vs. 1994 be –32.65 MPH. Dodge Caravan Many other pieces of information The second case involves a 2000 collected from the SDM were utilized Chevrolet Cavalier which collided in a in this case to verify the reconstruction. “t-bone” collision with a 1994 Dodge For instance the last speed recorded Caravan traveling perpendicular to by the SDM at –1 second before Algorithm Enable, (AE), is 67 MPH. the Cavalier.

The reconstruction yielded an impact The collision occurred on a dry asphalt speed for the Cavalier of 65 MPH. roadway in the nighttime hours. The The throttle position is at 0 for 4 roadway at the collision scene was a seconds prior to AE and the speed 2-lane east/west roadway intersected is steadily declining from a peak of by a 2-lane north south roadway. The 71 MPH. The –1 second indicates module was downloaded via a desktop the brake switch to be in the “on” download and the scene was measured position. It should be noted that the utilizing a Nikon Total Station, –1 second does not necessarily mean

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3.3 2001 Pontiac Sunfire vs. 2004 Hummer H2

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∆v1x = v3 cos(q ) − v1

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The reconstruction yielded an impact speed for the Cavalier of 65 MPH. The Cavalier in this instance was placed as vehicle #1 in the reconstruction. The approach angle, (α), was therefore assigned as 0o. The departure angle, (θ), was measured at 28o. Placing the data in formula 2.1, yields the following results:

A sensitivity study of the departure and approach angles was also completed in this case. In this case the most sensitivity was found when ranging the approach angles. The approach angle was adjusted from 86o to 95o and the range of longitudinal deltav was found to be –29 MPH to –39 MPH, respectively. When adjusting the departure angle of the Cavalier, the only variation was found below the decimal point.

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Veh. #1 (Cavalier): 36 MPH Veh. #2 (Caravan): 37 MPH

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The maximum recorded velocity change in the longitudinal direction recorded by the Sensing and Diagnostic Module can be found in Figure 3.1.3 as -12.91MPH. This is a difference of less than one percent.

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Figure 3.1.2

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∆v 2 Long = -13 −13 MPH

This calculated value indicates the change in velocity in the longitudinal direction for the H2. Now that can be compared to the values calculated from the measurements made by the SDM. Figure 3.3.3 shows the SDM file as it was downloaded from the H2.

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speed for the H2 of 46 MPH. The Sunfire was found to be traveling 29 MPH at impact. In this instance the Sunfire was placed as vehicle #1 in the reconstruction. The approach angle Based on the reconstruction the post for the Sunfire, (α), was assigned as impact speeds of the vehicles were 0o. The departure angle, (θ), was found to be as follows: measured at 70o. The Hummer’s approach angle, (ψ), was measured Vehicle #1, (Sunfire): 31 MPH at 90o and the departure angle, Vehicle #2, (Hummer): 34 MPH (φ), was measured at 77o. Based on this information being placed The reconstruction yielded an impact into equation 2.3 the following

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Computer Aided Drafting software.

Figure 3.3.1 is a photo of the Sunfire and Figure 3.3.2 shows a photo of the H2 involved in this collision.

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Figure 3.1.3

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The Sunfire’s departure angle, (θ), was measured at 70o. The post impact speed, (v3), was calculated to be 31 MPH and it’s impact speed, (v1), was found to be 29 MPH. When these variables are placed in equation 2.1 we find the following:

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In this collision both vehicles are SDM equipped vehicles, and both with pre-crash information.

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Figure 3.3.4 indicates 455 ignition cycles at deployment and 468 ignition cycles at download. This is because this file was down loaded two – three weeks after the collision at the body shop where the H2 was being repaired.

You will also notice in Figure 3.3.4 the speed at –1 second is indicated as 45 MPH and is fairly constant.

This information all corroborated the reconstruction.

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In this case the Hummer’s sensitivity to approach and departure angles was minimal. The departure angle for the Hummer as well as the departure angle for the Sunfire and approach angle were varied by 5 degrees on either side of the measured angles. There was less than 1 MPH difference found in the longitudinal delta-v calculations, falling within the reasonable precision of a reconstruction.

reported 32 MPH at –1 second. The impact speed of the H2 was calculated ∆v1x = -18 −18 MPH at 46 MPH, the calculated and Concern arises when compared to the measured delta-v match, and the speed download from the Sunfire as seen in reported by the SDM at –1 second Figure 3.3.6. There is no maximum was recorded as 45 MPH. This was delta-v recorded. Look to the table of constant, rising only 1 MPH from 44 delta-v recordings made very 10 ms, MPH within the previous 5 seconds.

Figure 3.3.8. The maximum delta-v A sensitivity study completed on the found on the table is -7.22 MPH at angles on this vehicle also showed 60 ms. a sensitivity to the approach angle, causing longitudinal delta-v’s ranging Let us consider some possibilities from –14 to –25 MPH. However the as to why this discrepancy may be readings in excess of –21 MPH are occurring. out of range as the associated impact speed is in excess of 36 MPH, defying 1. Review the SDM Data Limitations the common sense test. found on the first page of the printed report. There is specific information Based on all of these correlating datum regarding the particular module the SDM data seems to match the associated with the vehicle related to reconstruction and the discrepancy in the Vehicle Identification Number the delta-v data from the Sunfire may entered at download. In this case it be explained by one of the possibilities is noted that the delta-v data may previously discussed. be adjusted and, “may not closely approximate what the sensing system 3.4 experienced in all types of events.” 1998 Chevrolet Silverado vs. 2001 The example given in the Data Ford F150 Limitations speaks of the system adjusting for a rough road.

This case is an excellent example of the type of case in which the SDM 2. The maximum Delta-v value was data is dismissed as “useless” too often not reach in the Hummer until 172.5 just because the only data available is ms, much longer than the portion of the delta-v data. It is also a case in the pulse recorded by the Sunfire. which without careful analysis of the information available the data could 3.

Research has shown that as be grossly misconstrued. the PDOF becomes far off of the longitudinal axis, the SDM data This collision occurred in an asphalt becomes very sensitive to the vehicles intersection. The north/south road is attitude.2 a 4-lane roadway with center left turn lanes. The east/west roadway is also a Based on this information as well 4-lane roadway with center left turn as the availability of pre-crash lanes. The intersection is controlled information on both vehicles, further by a traffic control signal. The SDM analysis is necessary. from the 1998 Chevrolet Silverado was removed from the vehicle at the The impact speed of the Sunfire was scene and later downloaded benchtop calculated to be 29 MPH. The SDM because the electrical system in the ∆v1x = v3 cos(q ) − v1

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The SDM file indicates a maximum recorded velocity change of -12.18 MPH at 172.5 ms after AE, however, the crash pulse appears to be ending around 110ms mark. A review of the delta-v data indicates the delta-v curve flattens out at this point then much later, (172.5ms), reaches the –12.18 MPH mark. This indicates the crash pulse may have been over prior to the –12.18 MPH reading.

Possibly as early as 100 ms.

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Figure 3.2.2

Figure 3.3.1

Figure 3.3.2

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show the acceleration spike and come collision causes a rapid rotation about back to 0 to –1 g, assuming the entire the center of mass.

The Ford F150 was placed as crash pulse is captured, which in this vehicle #1 for the purposes of the case it should be as capture time is so This SDM allows deeper investigation reconstruction. Based on the crush long, 300 ms. Figure 3.4.4 shows as seen in Figure 3.4.4 with 300 ms of analysis seen in Figure 3.4.2, the this graph. crash data. The delta-v data that is approach angle of the Chevrolet, recorded around the end of the first (ψ), was established at 88o. Based A review of Figure 3.4.4 shows two event, (at 110 ms), is at -14.70 MPH. on scene evidence measured utilizing conspicuous peaks in the acceleration The calculated longitudinal deltathe Nikon Total Station, DTM 521, in this incident. The first incident v is -15 MPH. Assuming the later the Chevrolet was placed as close to appears to be over after approximately acceleration peak is from the slap or the area of impact as possible and the 110 ms. this is understandable and rotation up to the slap, the recorded departure angle, (φ), was measured is about what may reasonably be delta-v data is 98% of the calculated at 46o. The post-impact speed of the expected in this type of collision. The reconstruction value.

Chevrolet was estimated at 23 MPH g-forces then remain pretty constant; and the impact speed was calculated between 0 and 1 g’s until around 260 Adjusting the approach and departure to be 32 MPH. Based on all of ms where it appears there is another angles again makes little difference this information the delta-v in the spike in the acceleration curve. This and the calculated longitudinal deltalongitudinal axis of the Chevrolet was would indicate a secondary impact of v falls within the range. The largest calculated as follows: some sort. The photos of the vehicles range came by adjusting the departure involved in this collision show a clear angle of the F-150. By ranging the ∆v2 Long = v4 cos( b ) − v2 secondary “slap” at the rear of the departure angle 10 degrees, the range ∆v2 Long = -15 −15 MPH vehicles which could occur within of longitudinal delta-v became –13 this 300 ms time frame and could to –17 MPH. By varying both the This particular model of SDM only effect the delta-v. Figure 3.4.5 shows departure angle of the Chevrolet and offers 300 ms of post-crash delta-v, the secondary damage to the Silverado the Approach angle 10 degrees, the and no pre-crash information. Figure and Figure 3.4.6 shows the apparent ranges were within 1 MPH of the 3.4.3 shows the download. Because secondary damage to the F150. This SDM reported delta-v. this data does not give the maximum brings to the table an important recorded delta-v go to the max seen on discussion. When completing a the data table at the bottom of Figure linear momentum reconstruction, ONCLUSIONS 3.4.3. This indicates the maximum the reconstruction is based on the delta-v recorded by this SDM in idea that the two masses are point Based on the limited this collision is –20.18 MPH. This masses, and therefore no adjustment examples set forth above it is again a very large discrepancy. is made for any rotation about the is clear that the SDM brings to the Further investigation is necessary. center of mass. Clearly based on the table a new level of understanding of damage to these two vehicles there is the dynamics of real world collisions.

The total delta-v in the longitudinal rotation going on in this collision. If Information is recorded in a manner axis is recorded every 10 ms. One the vehicles in the analysis remain in which allows the investigator to item that would be of interest nearly the same orientation during develop a solid understanding of what in determining crash pulse is the crash, there acceleration.

The system records will be little error, Case Vehicle Calculated Recorded % the delta-v every 10 ms, therefore by however if there is 3.1 Cavalier -13.18 -12.91 97.95% finding the difference in the deltasignificant rotation, 3.2 Cavalier -33.82 -32.65 96.54% v, converting the value to fps, and the delta-v analysis 3.3 Hummer -12.64 -12.18 96.36% dividing by the time between each 3.3 Sunfire -18.02 -7.22 40.07% may not accurately record the resultant is the average 3.4 Silverado -14.99 -14.7 98.07% represent what acceleration over each 10 ms time the SDM records, period. When graphed this should Table 4.1 especially when the (c )

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Chevrolet was compromised.

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Figure 3.4.1

Figure 3.3.5

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Ford

Chevy

Figure 3.3.7 Figure 3.4.2 Figure 3.3.8

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not just the precrash information or Case Vehicle Calculated Recorded Maximum even as in case 3.4, 3.1 Cavalier -12 -12.91 -15 3.2 Cavalier -29 -32.65 -39 just the delta-v data 3.3 Hummer -12 -12.18 -13 on its face. To that 3.3 Sunfire -14 -7.22 -25 end the importance 3.4 Silverado -13 -14.7 -17 of understanding what the device is Table 4.2 recording in reference to the reconstruction could catch an investigator. The total is further emphasized by all 5 of these delta-v for the Silverado in case 3.4 downloads. A solid understanding of is 21MPH. The SDM recorded a the system is necessary for a proper longitudinal delta-v of 20.18 MPH. analysis. This data, if not properly On its face, it would appear that represented could create issues in these two figures match. As the basic court. Case 3.4 offers an excellent physics dictates these two figures are example of how an improper analysis not comparable, and an investigator (c

occurred in an individual collision in an unprecedented way.

The information collected can solidify the reconstruction and as demonstrated differences between the calculations and the actual data are attributable to known factors. Table 4.1 is a summary of the data listed in this paper. The recorded delta-v is shown as a percentage of the calculated, (by reconstruction), delta-v.

This table indicates the value of this device to verify the numerous pieces of a reconstruction. It also shows, as in cases 3.3 and 3.4, to look at the totality of the reconstruction and

Collision 25

first line in the collection of crash information. The crash information collected by law enforcement is often all that is available to entities such as the National Highway Transportation Safety Administration when investigating fatality collisions. Often the purpose of such investigations is to determine what, if anything, could have made a collision survivable. This technology brings to the collision investigator a new tool to validate the reconstruction in a unique way.

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ORKS CITED

2. Haight, W.R. “Rusty”: Automobile Event Data Recorder Technology – Evolution, Data, and Reliability: www.collisionsafety.net: 2002.

3. CDR Tool software Version 2.71. Help file and complete reports.

4. Daily, John; Shigumera, Nathan. Fundamentals of Applied Physics for the Traffic Accident Reconstructionist. Jacksonville Florida: University of North Florida, Institute of Police Technology and Management, 1997.

0.00 -2.00 -4.00 -6.00 -8.00 -10.00 -12.00 Tim e (s)

Figure 3.4.4 Damage from Secondary “slap”

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5. Daily, John. Fundamentals of Traffic Accident Reconstruction. Jacksonville, Florida. University of North Florida, Institute of Police Technology and Management, 1988. sh

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Figure 3.4.5

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Damage from Secondary “slap”

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6. Chidester, Augustus “Chip” B.; Roston, Thomas A. Real World Experience with Event Data Recorders. National Highway Transportation Safety Administration. Paper Number 247.

Figure 3.4.6 Collision 26

0.28

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1. Holt, Daniel J., ed. 100 Years of Vehicle Safety Developments. Warrendale, PA: Society of Automotive Engineers, 2005. 1087-1088.

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not properly trained could attempt to by the reconstructionist. However, make this improper association. the numbers in Table 4.2 speak for themselves. Approach and departure As with any reconstruction there angles indicated the most sensitivity. is a level of uncertainty. We are Ranging post-impact coefficients of unable to measure approach and friction made negligible difference in departure angles with a high level the outcome. of precision. Coefficients of friction vary dependent upon the exact It is essential for law enforcement surface, and tire type. Along that to embrace this technology and same vein, braking efficiencies vary thoroughly understand it so that depending on numerous factors that this information can better serve are uncontrolled and often unknown the public. Law enforcement is the

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Figure 3.4.3

Accident Reconstruction Calculator TM

By WeCARE Products and Education

Why do your calculations by hand?

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Energy Force Delta-V Crush Projectile Motion and more…

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

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

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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.

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CrAsh Data Case Study

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Knowing what to look for and where to find it

- Rusty Haight, Brad Muir eviewing crash data “downloaded” from an air bag control module using the Vetronix Crash Data Retrieval system can be at least confusing when one attempts to evaluate that data in the absence of an understanding of the normal components of a crash: the human, vehicle and environmental (H.V.E) components. At a minimum, a situationally complete* crash analysis needs to be done when one tries to make sense of the downloaded crash data.

both vehicles and photos of the involved vehicles. There are a series of issues offered for evaluation. These issues may or may not be the same from one instance to another but they are selected for discussion here and to give a more narrow focus to the case study at hand.

This case study is offered as an opportunity for the crash reconstructionist who is also trained as a Vetronix Crash Data Analyst to look at a set of case facts and evaluate some commonly encountered issues which often lead to confusion or misinterpretation. This case study is based on a documented crash test so there are “known quantities” involved. The issues and answers associated with this case study are appropriate for this case alone and may not be appropriate or applicable to another crash scenario given varying crash facts.

(1) There are two events recorded for the Cavalier, in what order did they occur?

n this instance, one should review the provided materials in an effort to address these points:

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(2) What is the most probably reason for the first event recorded and displayed in the Cavalier’s download? What action or impact caused the first event recorded by the Cavalier?

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(3) There is an apparent speed loss for the Cavalier over the period approximately 1 second to 2 seconds before “AE” where the reported speed appears to be 31mph then Here, the CDR system operator is given certain data ele- drop to 14 mph. There is a brake switch “on” indicaments from a 2 car crash. A 2001 Chevrolet Cavalier has tion at approximately 2 seconds before “AE” then “off” collided with a 2001 Chevrolet Lumina. One may review at about 1 second before “AE.” With those observations a scale crash scene diagram, data CDR downloads from in mind, what explanation can you give for the apparent * “Situationally complete” is used here to mean a crash analysis based on or which may be limited by (1) policy and/or procedure, (2) existing or available crash facts/evidence, (3) the existence of little or no visible roadway evidence, or (4) an individual analyst’s training and experience.

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speed loss over that second? One should explore possible explanations including: (3a) that there was “pre-crash data resampling (also know as “data buffering”)” for the “-1” samples and that speed is therefore under reported,

as “on,” the engine RPM is as high as some 3500RPM. What explanation can be offered for this apparent contradiction in the pre-crash data elements?

(5a) Identify investigative steps which might be taken to evaluate and explain the apparent contradiction in the pre-crash data seen in topic “5” above.

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(3b) that the brake switch status is reported incorrectly (reversed) for certain Cavaliers including the 2001 year model and this case we’re dealing (6) Relative to the data downloaded from the 2001 Luwith a 2001 Cavalier, mina, there are two events recorded for the Lumina, in what order did they occur?

(3c) there is actually braking pre-impact and that means the wheels on the Cavalier are locking and (7) The data downloaded from the Lumina does not discausing the speed to be under reported at the “-1” play any pre-crash data. Would this be an indication of a sample. “power interruption?”

(8) The Lumina download shows a non-deployment event. That non-deployment event shows a delta-V of -1.1mph over about 34ms. For the sake of this case study, one may assume that the actual, total delta-V for the Lumina is about -10.3mph. As it relates to this case study, assume that this value may have been calculated as part of a reconstruction. Explain the difference in the calculated delta-V of -10.3mph and -1.1mph as reported in the Lu(5) One may assume for the sake of this study, that mina data report. “redline”on the Cavalier is about 6000RPM. In the Cavalier download report, for the entire time captured for There may be other interesting components or aspects of “pre-crash data,” one sees “0” (zero) for percent throttle; this event that one may want to evaluate but to limit the however, the engine speed captured is as high as more than focus of this particular case study, these are the points se5000RPM. Even when the brake switch status is reported lected. Solutions can be found at page 97.

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(4) The delta-V for the Cavalier appears to be about 15.6mph at what is marked as the “90ms” sample on the delta-V graph and table for the deployment event. After that, in the “100ms” and then “110ms” samples, the delta-V takes an “upturn”or appears to become relatively less severe. What explanation can be given for this apparent “upturn?”

Case study scale scene map

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Case Study Scene Photos

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Case Study Vehicle Photos

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CDR File Information

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Vehicle Identification Number 1G1JC124717291759 Investigator Case Number Investigation Date Friday, July 15 2005 Crash Date Friday, July 15 2005 Filename CAVALIER FOR COLLISION.CDR Saved on Friday, July 15 2005 at 10:14:42 AM Collected with CDR version Crash Data Retrieval Tool 2.713 Collecting program verification number 7ABD298 Reported with CDR version Crash Data Retrieval Tool 2.800 Reporting program verification number 9238B95E Block number: 00 Interface version: 43 Interface used to collected data Date: 06-29-05 Checksum: 3200 Deployment Event(s) recovered Non-Deployment

SDM Data Limitations SDM Recorded Crash Events: There are two types of SDM recorded crash events. The first is the Non-Deployment Event. A Non-Deployment Event is an event severe enough to “wake up” the sensing algorithm but not severe enough to deploy the air bag(s). It contains Pre-Crash and Crash data. The SDM can store up to one Non-Deployment Event. This event may be overwritten by another Non-Deployment Event.

This event will be cleared by the SDM after the ignition has been cycled 250 times.

The second type of SDM recorded crash event is the Deployment Event. It also contains Pre-Crash and Crash data. The SDM can store up to two different Deployment Events, if they occur within five seconds of one another. Deployment Events cannot be overwritten or cleared from the SDM. Once the SDM has deployed the air bag, the SDM must be replaced.

The data in the Non-Deployment Event file will be locked after a Deployment Event, if the Non-Deployment Event occurred within 5 seconds before the Deployment Event unless a Deployment Level Event occurs within 5 seconds after the Deployment Event, and then the Deployment Level Event will overwrite the Non-Deployment Event file.

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SDM Data Limitations: -SDM Adjusted Algorithm Forward Velocity Change: Once the crash data is downloaded, the CDR tool mathematically adjusts the recorded algorithm forward velocity data to generate an adjusted algorithm forward velocity change that may more closely approximate the forward velocity change the sensing system experienced during the recorded portion of the event. The adjustment takes place within the downloading tool and does not affect the crash data, which remains stored in the SDM. The SDM Adjusted Algorithm Forward Velocity Change may not closely approximate what the sensing system experienced in all types of events. For example, if a crash is preceded by other common events, such as rough road, struck objects, or off-road travel, the SDM Adjusted Algorithm Forward Velocity Change may be less than and some times significantly less than the actual forward velocity change the sensing system experienced. This data should be examined in conjunction with other available physical evidence from the vehicle and scene when assessing occupant or vehicle forward velocity change. For Deployment Events and Deployment Level Events, the SDM will record 100 milliseconds of data after deployment criteria is met and up to 50 milliseconds before deployment criteria is met. The maximum value that can be recorded for SDM Adjusted Algorithm Forward Velocity Change is about 112 MPH. -SDM Recorded Vehicle Speed accuracy can be affected if the vehicle has had the tire size or the final drive axle ratio changed from the factory build specifications.

-Brake Switch Circuit Status indicates the status of the brake switch circuit.

-Some of the Pre-Crash data may be recorded after Algorithm Enable (AE). This may happen in situations involving relatively "soft" crash pulses or those that take place over a relatively longer period of time. If this occurs, it may affect the reported pre-crash data values, but does not affect other data such as SDM Adjusted Algorithm Forward Velocity Change.

-Pre-Crash Electronic Data Validity Check Status indicates “Data Invalid” if the SDM receive an invalid message from the module sending the pre-crash data.

-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.

-Passenger Front Air Bag Suppression Switch Circuit Status indicates the status of the suppression switch circuit.

-The Time Between Events is displayed in seconds. If the time between the two events is greater than five seconds, “N/A” is displayed in place of the time.

-If power to the SDM is lost during a crash event, all or part of the crash record may not be recorded.

-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”.

SDM Data Source: All SDM recorded data is measured, calculated, and stored internally, except for the following: 1G1JC124717291759

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-Vehicle Speed, Engine Speed, and Percent Throttle data are transmitted once a second by the Powertrain Control Module (PCM), via the vehicle’s communication network, to the SDM. -Brake Switch Circuit Status data is transmitted once a second by either the ABS module or the PCM, via the vehicle’s communication network, to the SDM. -The SDM may obtain Belt Switch Circuit Status data a number of different ways, depending on the vehicle architecture. Some switches are wired directly to the SDM, while others may obtain the data from various vehicle control modules, via the vehicle’s communication network.

-The Passenger Front Air Bag Suppression Switch Circuit is wired directly to the SDM.

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System Status At Deployment SIR Warning Lamp Status Driver's Belt Switch Circuit Status

OFF BUCKLED Air Bag Not Suppressed 8978 1

Passenger Front Air Bag Suppression Switch Circuit Status

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SDM Adjusted Algorithm Velocity Change (MPH)

1G1JC124717291759 Deployment Data 0.00

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System Status At Non-Deployment SIR Warning Lamp Status Driver's Belt Switch Circuit Status

OFF BUCKLED Air Bag Not Suppressed 8978 -0.56

Passenger Front Air Bag Suppression Switch Circuit Status

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Ignition Cycles At Non-Deployment Maximum SDM Algorithm Forward Velocity Change (MPH)

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Approximate Time Before Algorithm Enable (seconds)

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Hexadecimal Data This page displays all the data retrieved from the air bag module.

It contains data that is not converted by this program.

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93 23 00 00 95 6B 41 53 31 30 30 34 4B 37 59 56 50 32 00 22 63 22 46 89 01 89 7C 90 00 03 84 AB 80 85 84 85 C6 FF 00 FA 32 4A FA FA FA FA FA 32 4A FA FA FA FA FF 02 00 00 00 83 00 00 FF 80 FE FF BF FF FF FF FF FF FF FF FF FF FF 7C 0E 00 29 03 00 01 00 00 00 00 00 00 00 00 00 00 00 FF FF 0D 16 32 3E 44 4A 00 40 00 00 00 00 00 00 00 2F 37 42 49 4F 00 FB 9D FC FE 23 12 FF FF FF FF 00 00 00 00 28 09 03 83 00 00 FF 80 FE FF BF FF FF FF FF FF FF FF FF FF FF 7C 09 03 03 01 05 08 0D 13 18 1C 1E 1F 1D 1A FF FF FF FF 0B 45 03 FD 16 32 3E 44 4A 00 40 00 00 00 00 00 00 00 2F 37 42 49 4F 00 FB 9D FC 28 00 00 04 00 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

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$01 $02 $03 $04 $05 $06 $11 $14 $18 $1C $1D $1E $1F $20 $21 $22 $23 $24 $25 $26 $27 $28 $29 $2A $2B $2C $30 $31 $32 $33 $34 $35 $36 $37 $38 $39 $3A $3B $40 $41 $42 $43

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CDR File Information

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Vehicle Identification Number 2G1WL52J1Y1277477 Investigator Case Number Investigation Date Friday, July 15 2005 Crash Date Friday, July 15 2005 Filename LUMINA POST TEST.CDR Saved on Friday, July 15 2005 at 10:19:11 AM Collected with CDR version Crash Data Retrieval Tool 2.713 Collecting program verification number 7ABD298 Reported with CDR version Crash Data Retrieval Tool 2.800 Reporting program verification number 9238B95E Block number: 00 Interface version: 43 Interface used to collected data Date: 06-29-05 Checksum: 3200 Deployment Event(s) recovered Non-Deployment

SDM Data Limitations SDM Recorded Crash Events: There are two types of SDM recorded crash events. The first is the Non-Deployment Event. A Non-Deployment Event is an event severe enough to “wake up” the sensing algorithm but not severe enough to deploy the air bag(s). The SDM can store up to one Non-Deployment Event. This event can be overwritten by an event that has a greater SDM recorded forward velocity change. This event will be cleared by the SDM after the ignition has been cycled 250 times.

The second type of SDM recorded crash event is the Deployment Event. The SDM can store up to two different Deployment Events, if they occur within five seconds of one another. Deployment Events cannot be overwritten or cleared from the SDM. Once the SDM has deployed the air bag, the SDM must be replaced.

The data in the Non-Deployment Event file will be locked after a Deployment Event, if the Non-Deployment Event occurred within 5 seconds before the Deployment Event unless a Deployment Level Event occurs within 5 seconds after the Deployment Event, and then the Deployment Level Event will overwrite the Non-Deployment Event file.

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SDM Data Limitations: -SDM Recorded Vehicle Forward Velocity Change reflects the change in forward velocity that the sensing system experienced during the recorded portion of the event. SDM Recorded Vehicle Forward Velocity Change is the change in velocity during the recording time and is not the speed the vehicle was traveling before the event, and is also not the Barrier Equivalent Velocity. This data should be examined in conjunction with other available physical evidence from the vehicle and scene when assessing occupant or vehicle forward velocity change. The SDM records the first 300 milliseconds of Vehicle Forward Velocity Change after Algorithm Enable. The maximum value that can be recorded for Vehicle Forward Velocity Change is 56 MPH. -Driver’s Belt Switch Circuit Status indicates the status of the driver’s seat belt switch circuit.

-The Time between Non-Deployment and Deployment Events is displayed in seconds. If the time between the two events is greater than five seconds, “N/A” is displayed in place of the time.

-If power to the SDM is lost during a crash event, all or part of the crash record may not be recorded. An indication of a loss of power would be if the ignition cycles at the event is recorded as zero. Data recorded after that may not be reliable, such as Time Between Non-Deployment and Deployment Events, Driver Belt Switch Circuit Status, and Passenger SIR Suppression Switch Circuit Status.

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SDM Data Source: All SDM recorded data is measured, calculated, and stored internally, except for the following: -The Driver’s Belt Switch Circuit is wired directly to the SDM. -The Passenger Front Air Bag Suppression Switch Circuit is wired directly to the SDM.

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System Status At Deployment SIR Warning Lamp Status Driver's Belt Switch Circuit Status

OFF BUCKLED Air Bag Not Suppressed 11155 11159 10 N/A

Passenger Front Air Bag Suppression Switch Circuit Status

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Ignition Cycles At Deployment Ignition Cycles At Investigation Time From Algorithm Enable To Deployment Command (msec) Time Between Non-Deployment And Deployment Events (sec)

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2G1WL52J1Y1277477 Deployment Data

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-1.76

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System Status At Non-Deployment SIR Warning Lamp Status Driver's Belt Switch Circuit Status

ON UNBUCKLED Air Bag Not Suppressed 11158 11159 33.75 -1.10 Yes

Passenger Front Air Bag Suppression Switch Circuit Status

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Ignition Cycles At Non-Deployment Ignition Cycles At Investigation Algorithm Enable to Maximum SDM Recorded Velocity Change (msec) Maximum SDM Recorded Velocity Change (MPH) A Deployment was Commanded Prior to this Event

SDM Recorded Velocity Change (MPH)

2G1WL52J1Y1277477 Non-Deployment Data

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20 40 40 00 00 00 00 00 00 00 00 00 AA 00 00 00 00 00 00 00 AA 2C F9 F9 F9 F9 9F F9 F9 F9 FF 00 AA AA 00 00 00 00 00 7D 00 00 40 08 08 10 1A 22 2B 32 38 3E 42 46 4A 4B 4C 4C 4D 4E 4E 4F 50 50 50 50 50 51 51 52 53 54 55 56 2B 93 0B 00 00 FF 00 55 55 55 AA AA 01 AA 00 66 84 20 40 40 1B 05 00 02 04 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 2B 96 00 00 00 55 AA AA AA AA 00 00 00 00 7D FA 00 00 7D FA 00 00 7D FA 00 00 81 00 00 04 82 00 00 07 83 00 00 F7 84 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 92 6E C6 34 4E 1A 01 00 64 02 00 00 AA 00 00 00 00 01 01 BE CB B1 B4 B5 CB BE AC 69 AE B4 EF FA D0 00 00 00 00 FF FF 00 00 02 57 07 00 00 00 00 00 00 00 28 06 F0 05 50 06 10 2B 64 FF FF FF FF FF FF FF 48 4D 4F 4F 51 53 54 55 58 58 58 58 5A 6A 6D 6E 70 74 77 7A 7D 7F 84 84 8D B2 BB C1 C9 CB CD DC E8 EF F9 41 44 45 48 4A 4C 4E 50 52 55 56 58 59 5B 5D 5F 60 61 63 64 66 67 68 6A 6B 6C 6D 6E 6F 70 71 72 73 73 74 74 75 76 76 76 77 77 78 78 79 79 7A 7A 7B 7B 7B 7C 7C 7C 7C 7C 7C 7C 00 38 00 C8 0A 1C 50 24 13 14 08 14 AA 01 50 51 FF FF FF FF FF FF FF 45 4B 4D 4D 4E 50 51 52 55 55 55 55 57 5C 5E 5F 61 66 68 6A 6D 6D 6E 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 00 00 00 00 00 B2 DA 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

2G1WL52J1Y1277477

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B600: B608: B610: B618: B620: B628: B630: B638: B640: B648: B650: B658: B660: B668: B670: B678: B680: B688: B690: B698: B6A0: B6A8: B6B0: B6B8: B6C0: B6C8: B6D0: B6D8: B6E0: B6E8: B6F0: B6F8: B700: B708: B710: B718: B720: B728: B730: B738: B740: B748: B750: B758: B760: B768: B770: B778: B780: B788: B790: B798: B7A0: B7A8: B7B0: B7B8: B7C0: B7C8: B7D0: B7D8: B7E0: B7E8:

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00 00 00 00 00 00 00 00 00 00 A5 A5 A5 A5 75 FD

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MOTOR VEHICLE EVENT DATA RECORDERS Validation and Use of Data for Admission to the Court

NTRODUCTION

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Data collected from vehicle Event Data Recorders (EDRs) has been accepted by courts as evidence to be presented at trial. The validity of the data has been established by testing which has been documented

in scientific, peer-reviewed literature.

Technical literature and case studies are presented to demonstrate the accuracy and validity of the data, along with examples to describe the presentation of some critical information to respond to challenges.

Since 1994 data has been available to the accident reconstruction community from Event Data Recorders (EDRs) in certain General Motors automobiles.

Since 2000 to 2001, data has also been available from some Isuzu and

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BSTRACT

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Guy J. Barbera Olof H. Jacobson Bastiaan E. Cornelissen Christopher A. Thomas and Donald J. Anderson

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The EDR information discussed here focuses on data downloaded from GM and Ford vehicles using the Vetronix Corporation Crash Data Retrieval Tool. Data is also available Collision 44

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General Motors vehicles are equipped with EDRs that record data for non-deployment and deployment events. The data consists of velocity change during the event and, depending on model and year, the data may include precrash vehicle dynamic data and other important data such as seat belt use status.

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Daubert v.

Merrell Dow Pharmaceuticals (1993) set forth four specific factors which the court may apply to assist in determining the reliability of scientific testimony.

The trial judge acts as a “gatekeeper” to determine whether or not scientific testimony is reliable and relevant.

The judge may consider testing, peer review, error rates and “acceptability” in the relevant scientific community.

ENERAL MOTORS EDR DATA

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- A review of current legal standards; - An overview of GM and Ford EDR data; - A summary of “Pre-Crash Data” validations and limitations; - A summary of “Change in Speed (ΔV) During Impact” validations (including crash tests, real-world collisions, low-speed impacts, and a comparison of EDR and WinSmash data); and - A summary of “Change in Speed (ΔV) During Impact” limitations and anomalies associated with EDR data.

Frye’s “general acceptance” test was superseded by the adoption of the Federal Rules of Evidence which provided the standard for admitting expert scientific testimony in a federal trial. The Rules, especially Rule 702, assign the trial judge the task of ensuring an expert’s testimony both rests on a reliable scientific foundation and is relevant to the case. The Rules require that the testimony “assist the trier of fact to understand the evidence or to determine a fact in issue.” The judge must determine whether or not the testimony’s underlying methodology is scientifically valid and can be applied to the facts at hand.

The authors suggest that all of the factors listed in Daubert can and should be addressed with regard to EDR data. This paper summarizes references to show that EDR data, when properly interpreted, has been tested, has been verified by peer review, has a measurable error rate, and is widely accepted as reliable in the engineering and accident reconstruction communities. When using EDR data, the accident reconstructionist should verify factors relevant to the specific vehicle model and year involved because unique factors apply to some vehicles.

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Topics presented include:

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Historically, the courts used a standard set forth in Frye v. United States (1923). The Frye case established that scientific testimony must be based on methods which have general acceptance in the relevant field.

Kumho Tire v. Carmichael (1999) confirmed that the Daubert standards apply to other experts outside of the medical and pharmaceutical fields, including engineers.

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By providing a summary of technical literature and testing related to EDRs this paper will assist the accident reconstructionist in presenting the scientific basis for verifying the accuracy of EDR data, should the data’s validity be challenged in court.

EGAL STANDARDS

The court may consider one or all of the factors listed, however the judge is allowed flexibility and the entire list of specific factors does not necessarily or exclusively apply to all experts or to all cases.

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through other sources from heavy truck and bus data recorders, as well as other automobiles, however this data is not generally available without proprietary equipment from the vehicle manufacturer. While the principles are the same, these systems will not be discussed here.

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Ford vehicles. Over time the number of models with stored crash data has grown. EDRs store the data used to make the decision to deploy the airbag as well as additional data useful in accident reconstruction. The data is downloaded from the EDR with the Vetronix Corporation Crash Data Retrieval Tool. EDRs provide a source of information which can supplement traditional accident reconstruction techniques, however EDR data does not replace proper vehicle accident reconstruction.

For EDRs that store pre-crash data, the information can be associated with either a deployment or a nondeployment event. This data includes four pieces of vehicle dynamics

- Engine speed is typically sensed with a Hall Effect sensor on the crankshaft or camshaft. The signal is converted to a digital signal in the PCM and is sampled by the

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Lawrence (2003): Three 2002 model year GM vehicles had their SDM artificially triggered at vehicle speeds between 0.6 and 93 mph. Graphs of the pre-event speed captured by the SDM showed excellent correlation to the actual vehicle speed. The SDM generally over reported the vehicle speed by 1 mph at low speeds and underreported by 2.3 mph at high speeds.

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Fugger (2004): There was very good agreement between the preimpact speed recorded by the SDMs and the speed measured by the test instrumentation. Errors were generally less than 1 mph. sh

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Like GM EDRs, Ford records longitudinal change in speed (ΔV) and driver seat belt status. Ford also records longitudinal acceleration for all covered vehicles and the lateral component of acceleration and ΔV for the 2001 Sable and Taurus.

Additional data recorded by some Ford models includes passenger seat belt status, position of the driver’s seat (fully forward or not), and

Vehicle Speed:

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ORD EDR DATA

Specific tests which have been reported in the technical literature are summarized below.

The data should be corroborated by examining physical evidence where possible.

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- Driver’s seat belt status indicates the status of the driver’s seat belt switch circuit. If the vehicle’s electrical system was compromised during a crash, the belt may be reported as unbuckled even if it was buckled.

Analysis of the seat belt using standard accident reconstruction evaluation techniques should form the basis of determination of belt use.

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- Vehicle speed, measured by the vehicle speed sensor, is commonly sensed with a toothed ring gear on the transmission output shaft. The signal is normally converted to a digital signal in the Power Control Module (PCM) and transmitted via the Class 2 data link to the airbag module. The accuracy of the vehicle speed signal is reportedly ± 4% (Chidester 1999).

- The brake switch status is commonly read by a mechanical switch on the brake pedal and is transmitted by either the Anti-Lock Brake System (ABS) module or the PCM to the airbag module.

RE-CRASH DATA VALIDATIONS & LIMITATIONS

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In general, the vehicle dynamics information is as reliable and accurate as the device sending the particular signal. The “Sensing and Diagnostic Module (SDM) Data Limitations” section of the Vetronix download report should be reviewed carefully to identify any unique limitations specific to a given model. Following are overviews of each system (as well as the driver’s seat belt status) including a summary of relevant issues pertaining to each.

- The throttle position is commonly sensed by a potentiometer on the throttle shaft. It typically consists of a zero- to five-volt signal with a wiper that measures percent travel of the throttle plate. The signal is sent to the PCM, digitized and sampled by the airbag module.

The throttle position signal is used in the engine control system. The accuracy of the throttle position sensor is ± 5% (Chidester 1999).

time from algorithm enable to both airbag deployment attempt and pretensioner deployment attempt.

Ford EDRs do not provide pre-crash data. At this time the Ford data has not been tested as extensively as the GM EDR systems, however, the test data available suggests that the Ford ΔV data is as reliable as the GM recorded ΔV.

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Depending on the model, additional information may include driver’s seat belt status, number of ignition cycles at the event, number of ignition cycles at the time the data was retrieved, Supplemental Inflatable Restraint (SIR) warning lamp status and passenger-side airbag suppression switch position.

airbag module. The engine speed signal accuracy is reportedly ± 1 rpm (Chidester 1999).

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information recorded for five seconds prior to the event: vehicle speed, engine speed, throttle position and brake switch circuit status. Data is stored once per second, effectively giving five discreet readings at onesecond intervals before the event.

Niehoff (2005): In 28 crash tests with speeds ranging from 24 to 40 mph, the average error in pre-impact speed was 1.1%. The maximum error was 3.7% (1.3 mph).

Collision 45

Correia (2001): Seat belt status may Collision 46

Impact:

“A series of 48 vehicle-to-vehicle crash tests were performed involving 1996-2001 GM vehicles with closing speeds from 1 to 50 mph.”

Both GM and Ford EDRs record the longitudinal component of ΔV. Ford also records longitudinal acceleration

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EDR ΔV data is accurate and reliable but should be corroborated with traditional accident reconstruction techniques.

Note that errors occur when the entire crash pulse is not recorded.

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HANGE IN SPEED (ΔV) DURING IMPACT

the reconstruction of real-world collisions. EDR data has also been studied in low speed collisions.

While errors reported are in the range of 25% to 80% at low speed, the magnitude of these errors may be only a few miles per hour.

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Correia (2001): Brake status may not be synchronized with other precrash data and the pre-crash data may be skewed from the crash data by up to one second.

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Gabler (2003): GM EDRs continuously monitor the seat belt switch before and during a crash. If power is lost during the crash or the connection to the seat belt sensor is severed, the EDR may incorrectly record the belt as not buckled. GM reports this problem was corrected in newer EDR designs installed beginning in some 2002 model year vehicles.

During

The ΔV data has been verified in crash tests, including barrier tests and vehicle to vehicle tests, and in

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Gabler (2004) & VCU (2003): Seat belt use and seat belt status may not be synonymous – the belt may be buckled but not actually worn or worn improperly such as behind the back or with the shoulder webbing under the arm.

Fay (2002): Pre-crash data for individual elements could be out of phase with one another in time.

EDR ΔV Validations:

Chidester (1999): EDR data was verified in crash tests run by GM with vehicles propelled by a tow system and with the vehicle traveling under its own power to impact with a fixed barrier. The pre-impact and crash pulse data were all noted to be within defined limits, however, C

Chidester (2001): GM SDM (model “G”) units used in 1999 and some 2000 model year vehicles may incorrectly report the driver’s seat belt as unbuckled when it was actually buckled. Failure of the vehicle’s electrical system during the crash is the source of the problem.

Chidester (1999): There may be up to one second of time skew between the pre-crash and crash data.

For GM data the ΔV is reportedly accurate to ± 10% (Chidester 1999).

Based on the limited test data available, Ford EDR ΔV accuracy appears to be similar to that of GM.

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Seat Belt Status:

Asynchronous Pre-Crash Data:

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Virginia Commonwealth University (VCU) Crash Investigation Team (2003): For 2000-2002 Cavaliers the Brake Switch Circuit Status is reported opposite the actual status.

This problem is noted within the SDM Data Limitations section available in later versions of the Vetronix download software.

Niehoff (2005): Seat belt status was correctly recorded in all cases (n=34).

and the lateral components of acceleration and ΔV for the 2001 Sable and Taurus. Use of this data must take into consideration the orientation and heading of the vehicle at impact.

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Correia (2004): Note that brake status data indicates whether the brake pedal was depressed but does not indicate the degree of braking.

be incorrectly reported on some vehicles if the electrical system is compromised during the crash.

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Brake Status:

Comeau (2004): A series of eight crash tests was conducted on GM model year 1998-2002 vehicles.

Crash test configurations included

German (2001): Several case studies of accident investigations are presented involving GM vehicles.

The author’s analysis demonstrates the uncertainty associated with preimpact speed and the possibility of time skew between the pre-crash data and the initiation of the crash pulse.

Correia (2001): Two case studies of real-world crashes highlight the application of EDR data in conjunction with other reconstruction methods.

Uncertainties associated with EDR data (such as only reporting the longitudinal component of ΔV) can be resolved by analyzing physical evidence from the scene and vehicles.

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VCU (2003): This study compiled by the Crash Investigation Team of the Transportation Safety Training Center compares physical evidence with EDR output from eight realworld crashes occurring in 20022003. There is a high degree of reliability between EDR data and physical evidence, and EDR technology is a valuable tool when used in conjunction with accepted methods of crash investigation and reconstruction.

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Niehoff (2005): EDR output was compared with crash test instrumentation data for 37 crash tests conducted by NHTSA and IIHS. The tests involved mostly frontal impacts at speeds ranging from 25 to 40 mph. The 2002-2005 model year test vehicles were from GM, Ford and Toyota. Time shifting of the EDR data was required to align it with the test instrumentation data since the EDR only begins recording at algorithm enable, after

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German (2001): A series of 13 crash tests were performed by Transport Canada involving 1998 to 2000 GM vehicles and 2000 Ford Taurus vehicles. The test impact configurations included full frontal rigid barrier, offset deformable barrier and a fixed underride guard barrier (to simulate collision with the rear of a semi trailer). EDR ΔVs were compared to the vehicle impact speeds. Generally, there was good agreement with the EDR ΔV slightly higher than the impact speed owing to the rebound velocity associated with restitution.

EDR ΔV Validation in Real-World Collisions:

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Chidester (2001): EDR information was downloaded from 21 1998 model year GM vehicles that were subjected to FMVSS 208 or NCAP crash tests. The ΔV from the EDR generally corresponded well with, but was typically lower than the ΔV computed from the crash test instrumentation. Also, some of the EDRs failed to capture the entire crash pulse.

the EDR experiences an acceleration of 1-2 g’s. Plots of the ΔV curves show good agreement between the EDR and the test instrumentation, and when the EDR recorded the full crash pulse the average ΔV error was about 6% (15% max). The EDR ΔV was less than the actual ΔV in nearly all cases.

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Haight (2001): A series of 48 vehicle-to-vehicle crash tests were performed involving 1996-2001 GM vehicles with closing speeds from 1 to 50 mph. ΔV ranged from 0.2 to 25 mph. Twelve deployment events were recorded, with the remainder being non-deployment events. The SDM reported ΔV was, on average, 1.1 mph lower than the ΔV calculated from the crash test instrumentation.

full frontal impacts into a rigid barrier, 40% offset frontal impacts with a deformable barrier and full frontal impacts into a fixed underride guard barrier. Test speeds ranged from 25 to 40 mph. The GM SDM always reported a lower ΔV, 6% lower on average, than that calculated from the crash test accelerometers. This could be explained by the SDM missing the initial phase of the crash pulse due to the algorithm enable threshold of 1 to 2 g’s. Also, the sampling and averaging of the vehicle acceleration employed by the SDM may not capture all details of the crash pulse (i.e. peak accelerations might be clipped). The ΔV curves generated by the SDM were very similar to those generated from the test instrumentation for several of the tests. A time shift between the curves was noted and was attributed to the delay in reaching the algorithm enable threshold acceleration. Conclusions: GM EDRs generally report ΔV values within the stated +/-10% accuracy range (Chidester 1999); the SDM’s typically underreported ΔV so the values are considered accurate or, at worst, conservative; and converting the EDR ΔV values to average acceleration can be useful in interpreting and evaluating the results.

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no data is presented to support the conclusions.

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McClafferty (2004): Data from 52 real-world crashes involving GM vehicles compares the EDR reported ΔV with the ΔV calculated using damage analysis. When considering only central frontal impacts the agreement between the EDR and WinSmash ΔV was quite good (R2=.94, n=25). However, poor correlation was seen for cases with off-central frontal impacts (R2=.53, n=27). The lack of agreement in these cases was attributed to changes in vehicle rotational velocity and shifting of the vehicle front end.

Several case studies are presented to

EDR Data in Pedestrian Impacts: Fugger (2004): A series of tests were documented involving a pedestrian dummy being struck by various 1997-2002 GM vehicles with impact speeds ranging from 5 to 39 mph. Sixteen of the tests resulted

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Lawrence (2002): A total of 260 staged frontal collisions were performed with ΔV below 6.8 mph using 1997 and 1998 Chevrolet Cavaliers. In all tests the SDM reported ΔV was less than the actual ΔV. The maximum error at actual ΔVs of 3-4 mph was 2.5 mph. This error decreased to a maximum of 1.6 mph at a ΔV of 6 mph. SDMs always reported a near deployment event if the ΔV was

EDR Reported vs. WinSmash Calculated ΔV: Several studies compared EDR-reported ΔV with that calculated using the WinSmash computer algorithm. For centralaligned collisions there is good agreement between the two, and when collisions are beyond the capabilities of WinSmash, EDR data provides a superior measure of longitudinal ΔV. However, significant error in the EDR-reported ΔV was noted in cases involving vehicle rotation during a collision.

VALIDATIONS (continued) Chidester (1999): This case study shows the utility of EDR data to provide ΔV values when the collision is clearly beyond the capabilities of WinSmash such as in cases of severe underride.

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Wilkinson (2005): Three 2004 GM vehicles underwent 136 low speed impacts with ΔVs ranging up to 5 mph. For all tests the SDM reported ΔV was lower than the actual ΔV. Underestimates range from 0.1 to 1.8 mph. The SDM ΔV error increased with longer duration events and lower peak accelerations but was most sensitive to the duration. The ΔV threshold to generate an event ranged from 1.9 to 2.7 mph. Linear motion sled testing indicated the threshold accelerations to generate a near deployment event ranged from 1.1 to 2.7 g’s and that SDM accuracy did not change significantly over the range of ΔV up to 10 mph.

Wilkinson (2004) & Lawrence (2005): The study consisted of a 2003 Ford Crown Victoria and a 2003 Ford Windstar subjected to total of 84 low speed barrier collisions with ΔVs ranging up to 8.4 mph. The ΔV error reported by the Restraint Control Module (RCM) ranged from a 1.1 mph underestimate to a 0.2 mph overestimate. The RCMs tended to underestimate the actual ΔV due to incomplete recording of the crash pulse. This was noted in the acceleration curve as a nonzero initial or final acceleration, or an abrupt drop to zero acceleration before the end of the data file. There was also a problem with eight data points duplicated at the end of the acceleration curve determined to be a Vetronix CDR software version 2.1 problem. Lawrence (2005) reanalyzed the data with v2.4 software and the problem was resolved.

Some other minor differences in the interpretation of the data were noted when the v2.4 software was used.

in a near deployment event being recorded by the SDM. The SDMreported ΔV did not correlate well with the ΔV integrated from crash test accelerometer data, the SDM ΔV typically being higher. For ΔVs ranging from 0.3 to 1.3 mph the EDRs reported values from 0.4 mph below to 1.5 mph higher than the actual speed.

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Correia (2001): Twelve low speed crash tests were performed with a 1997 Chevrolet Cavalier and a 2000 Chevrolet Malibu. The Cavalier SDM reported ΔVs 0.8 to 1.4 mph below the actual for collisions in which the ΔV ranged from 3 to 4 mph. The Cavalier SDM had a near-deployment event ΔV threshold between 2.2 mph and 3.1 mph. The Malibu near-deployment event ΔV threshold was between 1.1 mph and 1.6 mph. The Malibu SDM underreported the pre-impact speed by a maximum of 0.7 mph.

greater than 3.8 mph. The speed change reported by the SDM likely defines the lower limit for a vehicle’s actual ΔV. Linear motion sled testing of SDMs showed that ΔV error increased with longer duration acceleration pulses and lower peak accelerations. Therefore, caution should be exercised when analyzing SDM data associated with underride and override collisions which often exhibit these characteristics.

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EDR ΔV Validation in Low Speed Impacts:

Missing Velocity Data in GM EDRs:

Niehoff (2005): Offset or angled impacts may have rotation such that the crash test accelerometers and the EDR may experience different accelerations.

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2004 Chevrolet Malibu: Niehoff (2005): In two Malibu tests the EDR recorded zero ΔV for the first 40ms. GM indicated this is a problem with the Vetronix software and is being corrected. ro up

Gabler (2004): When a vehicle experiences multiple crash events it may be difficult to identify which event was recorded by the EDR. For some later GM EDR designs, a deployment level event, which occurs after an air bag deployment, can record over a non-deployment event.

McClafferty (2004): EDRs are often mounted under the front seat away from the vehicle’s longitudinal axis.

In off-center impacts the vehicle’s change in rotational velocity will affect the longitudinal acceleration experienced by the EDR. Case studies presented demonstrate that for vehicles with substantial front end lateral deformation indicative of hard rotations, the EDR ΔV was not representative of the actual ΔV along the longitudinal axis.

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Multiple Events:

Vehicle Rotation:

Data Recording Duration:

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Gabler (2003): Non-zero velocity data could only be recovered from 37% of the near-deployment events analyzed. GM reports this problem is characteristic of their first EDR design capable of recoding precrash information. The problem was roughly confined to GM model

2003-04 Cavalier Reports Zero Speed Change:

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Chidester (2001): Failure of the 2000 Taurus/Sable electrical system during a crash results in an incomplete file saved by the EDR. Data is lost when this occurs.

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German (2001): This study attributed an incorrect air bag suppression switch indication to an electrical system failure.

Niehoff (2005): For the majority of the crash tests analyzed the EDRs had insufficient recording duration to capture the entire event.

German (2001): GM recalled 199697 Cavalier and Sunfire models for reprogramming of the SDM since certain calibrations resulted in an increased risk of air bag deployment in a low speed crash, or when an object strikes the floor pan.

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German (2001), Comeau (2004) & Gabler(2003): When the electrical system is compromised the GM SDM dataset may be incomplete. This can be seen as an abrupt discontinuity in the ΔV curve or other anomalous readings such as “Ignition Cycles at Deployment” at zero. This situation often results in final ΔV errors.

Comeau (2004): Even the 300ms recording window of the GM EDR was not sufficient to completely record the long duration underride impacts.

Inadvertent Air Bag Deployment:

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There are a variety of limitations and anomalies associated with EDR output. Interpretation of EDR data should consider the potential effects of such factors. The Data Limitations section of the Vetronix download report should also be reviewed for vehicle-specific limitations and anomalies.

Vehicle Electrical System Disruptions:

Gabler (2004) & Comeau (2004): One model of SDM records 100ms after the deployment criteria are met and up to 50ms prior (15 data points at 10ms increments). Examples are shown where less than 150ms was recorded resulting in incomplete crash pulse data and an incorrect final ΔV determination.

years 2000 and 2001.

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Gabler (2004): By comparing EDR-generated ΔV values with those generated by WinSmash for 65 single-event deployment cases from the NASS/CDS database, the authors concluded WinSmash underestimated ΔV 77% of the time.

On average the underestimate was 20%. (Study of GM vehicles only.)

EDR ΔV During Impact: Limitations

German (2001): The data in some Ford vehicles may be clipped at 78 milliseconds (ms) and the reported ΔV will be less than the actual.

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Wilkinson (2005): During low speed collision testing the Cavalier SDMs generated multiple zero ΔV events which overwrote higher severity Collision 49

events and in turn were able to be overwritten by lower severity events.

Some non-zero ΔVs with large errors were also recorded. Users should be aware that very low ΔV events (less than 0.6 mph) are potentially incorrect. up

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ONCLUSIONS

GM pre-crash data has an accuracy of ±4% for vehicle speed, ±1 rpm for engine speed, and ±5% for throttle position. ΔV has an accuracy of ±10%.

EDR data does not replace proper accident reconstruction which is performed according to the fundamental principles of physics.

Data recovered from EDRs must be interpreted in the context of the entire body of physical evidence involving the collision. EDR data must also be evaluated in the context

of available testing and information regarding unique issues involving the specific vehicle models involved because specific, unique factors apply to some vehicles.

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CKNOWLEDGEMENTS

The authors gratefully acknowledge Mr. James H. Chalat of the Chalat Hatten Law Offices in Denver, Colorado for his advice and input to the legal standards portion of this paper.

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Data from vehicle EDRs is reliable and accurate. The data has been extensively verified by testing and the results have been verified and published in peer reviewed technical literature.

Potential error rates have been quantified and published and the data is widely accepted as

accurate and valid in the fields of engineering analysis and accident reconstruction.

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REFERENCES Chidester, A., Hinch, J., Mercer, T., and Schultz, K. Recording Automotive Crash Event Data. Proceedings of the International Symposium on Transportation Recorders. Arlington, Virginia. May 1999.

2.

Chidester, A., Hinch, J. and Roston, T. Real World Experience With Event Data Recorders. Proceedings of the Seventeenth International Technical Conference on the Enhanced Safety of Vehicles. Amsterdam, Netherlands. June 2001.

3.

Comeau J.L., German, A. and Floyd, D. Comparison of Crash Pulse Data from Motor Vehicle Event Data Recorders and Laboratory Instrumentation. Proceedings of the Canadian Multidisciplinary Road Safety Conference XIV. Ottawa, Ontario. June 26-30.

4.

Daubert v. Merrell Dow Pharmaceuticals (92-102), 509 U.S. 579 (1993)

5.

Correia, J.T., Iliadis, K.A., McCarron, E.S. and Smole, M.A. Utilizing Data From Automotive Event Data Recorders. Proceedings of the Canadian Multidisciplinary Road Safety Conference XII. June 10-13, 2001. London, Ontario.

6.

Fay, R., Robinette, R., Deering, D. and Scott, J. Using event data recorders in collision reconstruction. Society of Automotive Engineers, 2002-010535. Warrendale, PA. 2002.

7.

Frye v. United States, 293 F. 1013, 1014 (D.C. Cir.1923)

8.

Fugger, T., Randles, B. and Eubanks, J. The Efficacy of Event Data Recorders in Pedestrian-Related Accidents (2004-01-1195). Accident Reconstruction (SP-1873). Warrendale, PA. Society of Automotive Engineers, 2004.

9.

Gabler, H., Hampton, C. and Hinch, J. Crash Severity: A Comparison of Event Data Recorder Measurements with Accident Reconstruction Estimates. SAE Paper No. 2004-01-1194. March 2004.

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10. Gabler, H.C., Hampton, C. and Roston, T. Estimating Crash Severity: Can Event Data Recorders Replace Crash Reconstruction? Proceedings of the Eighteenth International Conference on Enhanced Safety of Vehicles. Paper No. 490. Nagoya, Japan. May 2003.

11. German, A., Comeau, J.L., Monk, B., McClafferty, K., Tiessen, P. and Chan, J. The Use of Event Data Recorders in the Analysis of Real-World Crashes. Proceedings of the Canadian Multidisciplinary Road Safety Conference XII. June 10-13, 2001. London, Ontario.

12. Haight, W. Automobile Event Data Recorder (EDR) technology - Evolution, data, and reliability. <www.collisionsafety.net>. 2001.

13. Haight, W. Crash Data Retrieval (CDR) Data Analyst Certification Course. Lecture notes. Collision Safety, Inc. San Diego, CA. 2006.

14. IEEE Standard for Motor Vehicle Event Data Recorders (MVEDRs). IEEE Standard 1616-2004. Institute of Electrical and Electronics Engineers, Inc. 2004. <www.ieee.org>.

15. Kumho Tire Co. v. Carmichael (97-1709) 526 U.S. 137 (1999) 16. Lawrence, J. and Wilkinson, C. The Accuracy of Crash Data from Ford Restraint Control Modules interpreted with Revised Vetronix Software (2005-01-1206). Accident Reconstruction (SP-1930). Society of Automotive Engineers. 2005.

17. Lawrence, J., Wilkinson, C., Heinrichs, B. and Siegmund, G. The accuracy of pre-crash speed captured by event data recorders. Society of Automotive Engineers Paper No. 2003-01-0889. 2003.

18. Lawrence, J., Wilkinson, C., King, D., Heinrichs, B. and Siegmund, G. The Accuracy and Sensitivity of Event Data Recorders in Low-Speed Collisions. Society of Automotive Engineers Paper No. 2002-01-0679. 2002.

19. McClafferty, K., Tiessen, P. and German, A. Real World Comparisons of Calculated and EDR-Recorded Delta-V. Proceedings of the Canadian Multidisciplinary Road Safety Conference XIV. Ottawa, Ontario. June 26-30.

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20. McClafferty, K., Tiessen, P., Shkrum, M., German, A., White, J., Glazduri, V., Chan, J. and Deyell, P. A Study of Pre-Crash Events Using Information Retrieved from Event Data Recorders. Proceedings of the Canadian Multidisciplinary Road Safety Conference XIII. June 2003.

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21. NHTSA EDR Working Group; Event Data Recorder, Summary of Findings, Final Report; August 2001 [NHTSA Docket 99-5218-9 at http://dms. dot.gov].

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22. Niehoff, P., Gabler, H., Brophy, J., Chidester, A., Hinch, J. and Ragland, C. Evaluation of Event Data Recorders in Full System Crash Tests.

Proceedings of the 19th International Technical Conference on the Enhanced Safety of Vehicles. Washington D.C. June 6-9, 2005.

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23. Rosenbluth, W. Investigation and interpretation of black box data in automobiles: A guide to the concepts and formats of computer data in vehicle safety and control systems. West Conshohocken, PA: American Society of Testing and Materials, 2001.

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24. United States. House of Representatives. Committee on the Judiciary. Federal Rules of Evidence. Washington, D.C. U.S. GPO. 2004.

25. Vehicle Event Data Interface -Vehicular Output Data Definition (J1698). Society of Automotive Engineers. 2005. <www.sae.org> 26. Virginia Commonwealth University. Transportation Research Center. Crash Investigation Team. Special Report Number 16, Rev. 2/03. August 2003.

27. Wilkinson, C., Lawrence, J., Heinrichs, B. and King, D. The Accuracy and Sensitivity of 2003 and 2004 General Motors Event Data Recorders in Low-speed Barrier and Vehicle Collisions (2005-01-1190). Accident Reconstruction (SP-1930). Society of Automotive Engineers. 2005.

28. Wilkinson, C., Lawrence, J., Heinrichs, B. and Siegmund, G. The Accuracy of Crash Data Saved by Ford Restraint Control Modules in Low-speed Collisions (2004-01-1214). Accident Reconstruction (SP-1873). Society of Automotive Engineers. 2004.

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- Sgt Chuck Veppert Ohio State Police

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- The historical progression from data recorded by the early SDMA and SDMB through the current SDMGF and SDMDW modules including a discussion of multiple deployment files in early modules, relatively low maximum deltas-V captured, where 300ms of delta-V vs 150ms may be captured and the apparent uniformity in relatively “early” modules.

- Differences in data recorded in Deployment vs NonDeployment events - Cautions related to reviewing or storing events saved as pdf - An explanation of maximum delta-V recorded comparing actual maximum vs data limitations approximation - A discussion of the changing data points recorded over the different models - Data differences in the same module/different car line

The data for this research was collected from CDR downloads performed by the OSHP, from the CDR Yahoo Group website files, and by numerous other CDR users who responded to a request on the CDR Group forum.

Each was opened and documented as to the Year/Make/ Model (using the vin if not identified). The data for each file was sorted by module type, with any interesting identifying numbers also noted. The event files submitted by private users for this project will be destroyed after final completion of the spreadsheet. The spreadsheets found on the data CD that comes with this issue of Collision should be considered a “work in progress” and are current to the research as of February 2006. Additional data is still being added to the spreadsheets as they’re found on the CDR User’s Group Yahoo site.

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- Discussion on the variances observed in what data is recorded on the SDMGF (used in may 2002-2005 models) - Data on FORD RCMs is included, but limited due to the small supply of event files at the time this research was compiled.

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s part of the CDR Conference, Ohio State Police Sgt Chuck Veppert presented his research relating to which specific air bag control modules are found in which vehicles currently accessible by the Vetronix CDR System. Sgt Veppert’s presentation was a review of a spreadsheet of the data contained in events files from 16 models of GM and 3 models of Ford ACMs including:

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A Review of Various ACM Module Types and Data Recorded

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From the document: “Veppert ACM by vehicle.pdf ” one can view a list of CDR accessible vehicles and find the direct connect (“umbilical”) access cable number, location of the module and designation of the airbag control module itself.

On the Collision Data CD, there are folders for each author from the 2006 CDR User’s Conference. Each folder bears the name of the relevant author. In the case of Chuck Veppert, there are two reference documents in Adobe Acrobat “PDF” format: “Veppert - ACM by vehicle.pdf ” and “Veppert – data by ACM.pdf.” An example of a screen from the document “Veppert - ACM by vehicle.pdf ” is shown above. One can look through the list of Vetronix CDR supported vehicles by year, make and model and find not only which cable would be used for an umbilical download and where the airbag control module would be found in the car but also find out, for many of those vehicles, which model air bag control module is installed. The document “Veppert – data by ACM.pdf ” shows what data elements might be expected in the report generated by the CDR software after a successful download categorized by the module designation found in the previous list by vehicle make and model. Adobe Acrobat reader is also found on the Collision Data CD.

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From the document: “Veppert – Data

by ACM.pdf ” one can view a list of modules for CDR accessible vehicles and find a list by deployment (“D”) and non-deployment (“ND”) events of what data elements one might expect to recover after a download.

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- William Messerschmidt

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Rational Legislative and Organizational Policy for Automotive Event Data Recorders

EFINITIONS

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Event Data Recorder (EDR): Manufacturer installed electronic components such as airbag control modules, electronic throttle control modules, or heavy truck electronic control modules (ECMs) capable of recording data as a result of a sudden change in the physical properties of a vehicle’s motion (i.e., and “event”). The captured data may include information concerning the motion of the vehicle, performance of a vehicle, vehicle system status, or diagnostic fault codes. This recording function is specifically triggered by the physical attributes of the event, and data are written to memory only within the EDR.

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One means of protecting Event Data Recorder (EDR) technology from legislation based on popular misconceptions is the development of standardized and equitable organizational policy by those who employ EDR technology.

This thesis is advanced by first defining legislative and organizational policy.

After defining policy, an overview of the public reaction to EDRs is offered. Based on this reaction, future EDR policy is described as a High Ambiguity – High Conflict scenario, as defined by Richard Matland’s It is proposed that following such Ambiguity-Conflict Model.

The application of this model shows the need for consensus building among the various interest groups involved in transportation safety. It is further argued that creation of consistent and fair organizational policy is a key first step in protecting EDR technology and facilitating consensus among the various interest groups. recommendations will help protect After showing the need for the technology from restrictive written policy guidance, specific legislation, because it is a crucial recommendations are made to assist element of consensus building and

public acceptance.

Furthermore, good organizational policy will also help protect agencies that employ EDR technology from negative publicity, legal liability, and adverse evidentiary decisions.

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administrators in the creation of workable policy and procedure for EDR use. These recommendations emphasize the importance of: • training for EDR users • compliance with state and federal rules of evidence • consistency with existing policy • clarity in defining parameters of EDR use in employee discipline • preventing top-down micromanagement of EDR users and technology

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BSTRACT

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Legislative Policy: Whatever a government chooses to do or not do.

Organizational Policy: The actions

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EDR policy has not been addressed, especially for law enforcement agencies, by their usual sources of guidance, such as the International Association of Chiefs of Police (IACP), the Commission for the Accreditation of Law Enforcement Agencies (CALEA), and the Progressive Policy Institute (PPI).

Presently, none of these organizations have offered specific guidance or advice on the use of EDR technology. ra

The goal of this paper is to present a more specific approach to influencing public policy than simply to advise launching an educational campaign, (though that is clearly one desirable step in the process). In order to influence public policy with regard to EDRs, the consensus in the scientific community that the EDR is valuable and reliable technology must be broadened to the enforcement and education communities, as well as to the mass media. Departments of public safety, school educators, and

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In the court of public opinion, Event Data Recorder (EDR) technology is new and controversial.

However, the reality of the situation is much different. EDR technology is not new or novel science, and many of the public concerns are based on misunderstandings about EDR technology. For the purpose of this research, the EDR has been defined according to its relevant parameters in contemporary collision reconstruction and does not include

A key aspect of building such a consensus is the implementation of simple, but fair and well-defined, organizational policy for the use of the Crash Data Retrieval Tool and other EDR-reading systems. Almost any tool can be used improperly, and the EDR is no exception.

Straightforward examples of improper EDR use would be decision-making based on an EDR analysis performed by an unqualified person, or the use of EDR data as a “selective enforcement tool” or disciplinary tool targeted at a group of citizens or employees.

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NTRODUCTION

The full report recommends that: “To alleviate public concerns about EDRs, those organizations or agencies wanting to use EDR data should promote education about what EDRs can actually do. The automotive manufacturers, USDOT, and state transportation agencies are encouraged to conduct a more thorough public education campaign to inform the public about the presence of EDRs in passenger vehicles and about the safety and research benefits for the motoring public.”

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Word on “Policy” This paper contains a discussion of two separate types of policy: legislative and organizational. In both cases, Thomas Dye’s definition of public policy is used. Therefore, if various governments allow the collection and use of EDR data by writing no new restrictive legislation and simply holding EDR data to the same rules that apply to other accident-related evidence (i.e., bulb filaments, tires, or safety belts) then there exists a permissive legislative policy with regard to EDR data use. With regard to an organization, it is the thesis of this paper that there should be a written organizational policy to govern the use of EDR data. In the absence of such a written policy, the pattern and practice of the organization will be viewed as its “policy.”

When properly evaluated, EDRs are an invaluable tool for crash investigators, whether their motivation for reading EDR data is vehicle safety, highway safety, or criminal or civil litigation.

As summarized by the Transportation Research Board in Research Results Digest 298, “EDRs offer a remarkable new data source for improvements in highway crash data analysis and research.”5 As the Digest goes on to state, however, “the issue here is not so much of legal authority to use EDR data in court, but instead, what the public will accept.”

representatives of non-government organizations (NGOs) must be convinced that the EDR is a fair and accurate tool to be employed in accident investigations, and they must be willing to publicly express these views. The experience of the European Union must be considered and communicated: as reported by Schmidt-Cotta, “fleets throughout Europe have reduced accident and damage costs by approximately twenty-five percent or more” when they have installed accident data recorders in their fleet vehicles.

Furthermore, the a fore mentioned groups must work in concert with auto manufacturers, state, and federal transportation agencies to promote acceptance of EDR data.

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Satellite Tracking System (STS): Any monitoring device that tracks a person or vehicle, typically with the use of a global positioning system, such as Qualcomm, Lo-Jack, or OnStar.

satellite-enhanced tracking systems or security systems such as Qualcomm, Lo-Jack, or On-Star.

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that an organization chooses to do or not do.

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This is a significant lapse. As pointed out by Haight, “since criminal cases generally find their way to court sooner than civil cases, crash data extracted using the CDR [Crash Data Retrieval] System started finding its way into criminal courts in late 2000, and they continue in 2004.”

“Event Data Recorder,” “CDR,” “Crash Data Retrieval,” and “Black Box & Car” were searched in this database of 200 local and 30 national newspapers. Figure 1 indicates the results of this brief search. 53% of the articles focused on privacy concerns for the individual motor vehicle operator, while 35% focused on the utility of EDR data in helping advance research or police investigations.

The remaining 12% of the articles focused on the debate between safety and privacy.

Other, more formal and detailed research yielded similar results.

Thomas Kowalick analyzed the responses of 80 other safety, enforcement, or business college age adults for the research professional, these data—when presented in Real World Perceptions properly evaluated and understood— of Emerging Event Data Recorder provide an invaluable tool for fair and Technologies. Kowalick’s respondents accurate decision-making. were presented with an informational news piece and asked to identify Current legislation dealing with potential positive and negative aspects EDR technology seems to indicate of EDR technology. Of the negative that the public perception of this technology may be quite different from that of researchers and accident investigators. As of 20 January 2006, 6 states had enacted laws which restrict access to EDR data and an additional ten states have legislation pending that would restrict access to the data. A search of newspaper archives contained in the EBSCO database was conducted as a preliminary test of this hypothesis. Articles containing the words “EDR,”

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Crash investigators and safety researchers are well aware of the data provided by EDRs of all types. From Electronic Control Modules (ECMs) available on heavy trucks to the Airbag Control Modules (ACMs) accessible by the Vetronix CDR Tool, the data that are gathered

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ACKGROUND

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This paper first explains why written policy on the part of organizations using EDR technology can be a beneficial step in protecting EDRs from those who oppose their constructive use; next it presents a guideline for developing a written organizational policy that is effective and equitable. By application of the Ambiguity-Conflict Model of policy implementation, it is hypothesized that the creation of such organizational policies at the local level will support and encourage the development of rational legislative policy.

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“The danger to the traffic safety community of failing to respond to this erroneous recasting of the EDR debate is that “rights” and “privacy” are powerful and easy to communicate ideas”

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This situation clearly places law enforcement agencies on the forefront of EDR acceptance, not only in the legal system, but also in the media, which has often reported the involvement of EDR data in otherwise typical traffic accident-related prosecutions.

can be compelling and accurate when interpreted by a competent analyst & . Whether the EDR’s enduser is a research scientist; corporate risk manager; police accident reconstructionist; private engineer; or

responses, 63% of these concerns were not applicable to EDRs, as defined by collision reconstructionists and in existence today, but were applicable primarily to STS that include a data archive. Twenty-three percent of the concerns related to the EDR data being misused either by police, insurance agencies, or other corporations. Nine percent of the concerns were related to the fact that the EDR may not be “infallible,” and 5% of the concerns related to public ignorance of the technology.

dampened by human emotions. As James Q. Wilson, Collins Professor of Management at the University of California, Los Angeles, stated in an address on the 50th anniversary of the RAND Corporation,

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In their 1997 publication, Road Safety Principles and Models, the Organisation for Economic Co-Operation and Development (OECD) concluded:

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The implementation phase of road safety work is overlooked in the road safety research area. This also means that theories and models concerning ignorant of what data are captured by the implementation process are not EDRs, how such data are retrieved, developed in the same way as they are how and why EDRs function. Second, in road safety research of the more this misunderstanding gives rise to a conventional character. re-casting of the debate surrounding EDRs into a debate over privacy An attempt is made to address this rights and government intrusion. deficiency, specifically with regard This is not an atypical situation. to EDR technology. To determine L.W. Sumner describes the general the appropriate response to the volatile misunderstandings of EDR situation in Western democracies: Like the arms race the escalation of technology, the Ambiguity-Conflict rights rhetoric is out of control… Model of policy implementation there is virtually no area of public that was proposed by Dr. Richard controversy in which rights are not to Matland was employed. This model be found on at least one side of the divides a potential policy (here, legislative response to EDR data) into question – and generally on both. two aspects: the level of disagreement The danger to the traffic safety it engenders (intensity of conflict) community of failing to respond and the level of knowledge that the to this erroneous recasting of the constituencies have regarding the EDR debate is that “rights” and policy (ambiguity). It is important to point out that the ambiguity is not )2

This paper assumes somewhat of a modernist approach to public policy, by supposing that public policy should be rational and based upon the best available scientific evidence.

Nutley, et. al wrote, “There is nothing new about the idea that policy and practice should be informed by the best available evidence.” Such sentiments are particularly strong in the scientific community, where the scientific method is used to generate knowledge. Nutley et. al describe the foundations of rational theory as being grounded in the Enlightenment. This corresponds with the historical superseding of science over superstition. Though rational beliefs are not restricted to the scientific community, the principle of rational policy creation is often

ETHODOLOGY

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Everyone wishes public policy to be rational. We prefer knowledge to ignorance and insight to superstition.

To argue otherwise would seem to make us less than human. Of course, much of life is ruled as much by emotion and ambition as by inquiry and thought. We are humans, shaped From 2001 to 2004, theTransportation by passions and interests as well as by Research Board (TRB) conducted reason and detachment. We cannot an extensive series of surveys to help be otherwise. determine public opinion about EDR Wilson’s quote summarizes the technology. This research consisted of current state of EDR legislative policy. approximately 10,000 mailed surveys Rational scientific reasoning has come followed up by focus group meetings. into conflict with an emotional desire The TRB concluded: “Finally, it is for “privacy” on the public roads. abundantly apparent that our survey After reviewing the public opinions on and focus group opinions reflect the EDR technology, the problems facing general population’s opinions, some of organizations which seek to use EDR which are based in misconceptions.” data become clear. First, the public is

“privacy” are powerful and easy to communicate ideas. As Alan Schmid writes in Property, Power, and Public Choice, “Ideas for reform must be condensed into a slogan to fit a headline.” The common phrases such as “Big Brother,” and “black box” certainly can and do fit the headlines and solicit an emotional response. Echoing Schmid, Sumner writes, “Clearly, interest groups which converge on little else agree that their rights are indispensable weapons in political debate.”

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To show the application of the Conflict - Ambiguity Model to traffic safety generally, and EDR technology specifically, Figure 2 shows an example of each scenario.

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Encouraging Rational Legislative Policy for EDR Use Matland hypothesizes that the policy outcome will be dependant upon the coalition strength of those who seek to create legislative policy. Matland states, “The central principle is that at the local level, coalitional strength determines the outcome.” This is consistent with Nutley, who writes “Partnership models, which encourage ongoing interaction between evidence providers and evidence users, may be the way forward.” In the case of EDRs, the outcome desired by the scientific community is that legislative policy (in the US, specifically state laws) will be created in a rational manner, based upon the scientific evidence that EDR technology will improve highway traffic safety and assist civil and criminal investigators in making correct determinations in accident investigations.

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the TRB report on EDR technology states that the use of EDR data does not in itself constitute a violation of anyone’s rights under the US Constitution. However, individual states are free to pass their own, more restrictive legislation. This is exactly what has happened in six US states, and what is proposed in 10 others.

This circumstance was predicted in

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One traditional approach to dealing with ambiguity has been to attempt to eliminate it. In the case of EDR technology, this would involve the comprehensive education of potential voters.

While education efforts will certainly be necessary, Matland points out that “at times, ambiguity is more appropriately seen as a fixed parameter” that cannot simply be eliminated. This may stem from “a poor understanding of the problem.”

Data such as those collected by Kowalick and the TRB are certainly indicative of a poor understanding Furthermore, the elimination of of the issues surrounding EDR ambiguity through education would not necessarily lead to “automatic” technology. or “easy” acceptance of rational There are two specific reasons why EDR policy. As demonstrated by ambiguity with regard to EDRs the Ambiguity-Conflict Model, the might be accurately seen as a “fixed policy outcome of a Low Ambiguityparameter.” The first is that EDR High Conflict policy is determined by issues deal with a mixture of legal the political strength of the opposing and engineering issues. Both of parties. Using the Ambiguity model, these fields are poorly understood by a matrix can be built where a policy the general public (they are highly falls into one of the following four specialized fields requiring several areas: years of specific education, after which additional requirements are 1) low conflict, low ambiguity imposed for licensure). Unlike the 2) low conflict, high ambiguity case of safety belts (whose acceptance 3) high conflict, low ambiguity also relies on engineering and legal 4) high conflict, high ambiguity knowledge), there is no direct causal relationship between a person having Given the level of misunderstanding an accessible EDR and that specific in association with the passionate person being safer, as is the case with nature of the privacy debates safety belts. With EDR technology, surrounding EDRs, EDR legislative the benefits, such as those reported policy clearly falls into the high

by Schmidt-Cotta are more diffuse, conflict, high ambiguity category. and the safety enhancements available This categorization is consistent with

the scenario predicted by Matland, who wrote, “Policies that invoke salient symbols [privacy, in this case] often produce high levels of conflict even when the policy is vague” [poorly understood by the public, in this case].

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through data analysis are long term.

The second reason why EDR acceptance may not be facilitated by education alone can be seen in the data gathered by the TRB, which reported that “survey and focus group opinions mirrored what GM found in a recent survey, that self-labeled safer drivers are more accepting of CDRs than those who admitted to some minor traffic ‘transgressions’.” This indicates that without a widespread change in driver behavior, some drivers will oppose the use of EDR technology, and it would seem that these opponents will be those who are most likely to be the subject of accident investigations. Because of this potential opposition, an approach to policy implementation must be designed that will anticipate conflict in spite of education.

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factual disagreement in the relevant scientific community (although the model could be applied to such a hypothetical case). With regard to legislative policy outcomes surrounding EDRs, ambiguity refers only to the level of constituent understanding.

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As demonstrated by the AmbiguityConflict Model, local coalition strength will be the determining factor in what legislative policy is implemented. This scenario has been borne out in past experiences in the traffic safety community, particularly in the application of per se limits for driving under the influence of alcohol, mandatory seatbelt usage, and the acceptance of police radar as a tool for traffic enforcement. In all of these instances, the scientific community, law enforcement, government, and NGOs have worked in concert to affect rational policy creation, increase public awareness of the problems, educate the public to steps that can be taken, and provide both positive and negative incentives for complying with the enacted legislative policy. Furthermore, in these cases, the actions of all parties,

Effective and Equitable EDR Organizational Policy The creation of an effective but fair written organizational policy for EDR use is an important first step in coalition-building. If the users cannot supply potential allies, such as legislators, government administrators, non-profit safety and education groups, with proof of a clear, equitable, and well reasoned approach to obtaining EDR data, these potential allies will find it difficult to support the use of a technology that they themselves may find ambiguous or controversial.

Worse still, any perceived improper use of EDR technology is likely to generate substantial attention in the media, which will continue to cast the political debate as one of liberty versus government intrusion.

Low Conflict

High Conflict Political Implementation

Dependant Upon: Resources

Dependant Upon: Political Power

Example: use of a Total Station for creating site diagrams

Example: standardized training/education requirement (PE license or ACTAR accreditation) to testify in accident cases

Experimental Implementation

Symbolic Implementation

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Dependant Upon: Contextual Conditions

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Administrative Implementation

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As previously noted, 63% of Kowalick’s respondents indicated concerns with EDRs that are unrelated to the technology accessible through the Vetronix CDR Tool or various truck manufacturers’ ECMs. Reiterating Wilson’s comment, “We prefer knowledge to ignorance and insight to superstition.” Fears as stated by these respondents, such as, “EDR Technology may make it possible to place private vehicles under continuous surveillance,” clearly fall

especially law enforcement, were most often transparent and supported by formal written policy governing how the legislation would be enforced.

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The importance of coalition-building among the various interest groups in the traffic safety community has shown its utility in the past, and its potential to create change in public opinion should not be underemphasized.

Drinking and driving has become less acceptable and more severely punished through such coalitional strength. In the case of legislation dealing with intoxicated drivers, citizen action groups, who had no legislative or judicial power alone were dramatic elements in effecting change in US driving habits.

Leonard Evans, president of Science Serving Society, states, “Citizen activist groups deserve major credit for a portion of the 15,000 traffic deaths per year reduction from the early 1980s to 2002.”

into the categories of ignorance and superstition and cannot be the driving forces of a rational EDR legislative policy.

High Ambiguity

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2004 by Schmidt-Cotta, who wrote: “As such devices occupy an everincreasing number of vehicles, it is likely that governments (including the other forty-nine states) will need to take legislative action to clarify the various issues arising from the use of this technology.” It is precisely this clarification that must be based on the rational interests of society and the Constitutionally plain notion that the public roads are, in fact, a public place.

Example: Formation of a DUI Task Force

Dependant Upon: Coalition Strength Example: Use of EDR Technology

Figure 2: An Application of the Ambiguity – Conflict Model to Traffic Safety Collision 61

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When an agency drafts a policy addressing the use of EDR technology, the authors must include individuals who have been trained and certified in the use of EDR technology. Furthermore, law enforcement agencies need to careful not to simply rubber stamp existing polices for searches of motor vehicles and apply them to an EDR policy.

Most current polices and criminal

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Figure 3: Reactive policy creates a cycle.

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A Proactive Policy Too often, agencies of all types engage in creation of reactive policy. This policy is often made as a reaction to a perceived mistake or error.

The cycle shown in Figure 3 begins when an employee takes initiative and performs some act that is later perceived to have a negative outcome by the agency leaders. The negative outcome leads to a prohibition of the activity, even if the employee’s action has been uncontroversial or even beneficial in the past. Following the creation of this restrictive and reactive policy, organization members learn to avoid initiative and believe that policy itself strips them of the ability to use creativity or perform their normal duties without direct supervision.

Elements of an Effective and Equitable EDR (Organizational) Policy

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Chief Orrick’s sentiments are not only true for police agencies. They are correct in any context. In the absence of clear instructions, confusion and failure are likely outcomes. To facilitate the creation of EDR policy that will abet confusion and failure, the following advice is suggested for those who use EDR technology.

part of the agency to its constituent groups and coalition members seeking to retain the use of EDR technology as a tool for investigation and research.

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When properly developed and implemented, a policy-procedure manual provides staff with the information to act decisively, consistently, and legally. It also promotes confidence and professional conduct among staff.

With this perspective, agency members can be slow to create or support policies governing new technology or programs. But by not crafting proactive written directives, the leadership’s expectations or requirements are often not communicated clearly, understood precisely, or remembered appropriately. When this is the case, the chance that any employee initiative will be found unfavorable and eventually forbidden by a new, reactive policy increases. The theory presented here is that if sound policy (policy that is fair, effective, and efficient) is enacted from the start, then the use of EDR technology is less likely to be prohibited or restricted internally by future administrations, and the carefully written proactive policy will evidence good faith on the

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Adherence to sound policy is a strong factor in preventing such improper use of EDR technology. Chief W. Dewayne Orrick describes the utility of a policy manual in Developing a Police Department Policy-Procedure Manual. His general comments can be directly applied to EDR technology.

case laws that address vehicle searches deal with situations where the vehicle is being searched for evidence of another crime. With regard to the use of EDR data, a part of the vehicle itself is the evidence.

One of the primary EDR misconceptions noted by Kowalick deals with exactly what an EDR captures.

Concerns noted by Kowalick include: “Links to the GPS constellation of satellites may make it possible to track the whereabouts of private vehicles at all times.” If this were true of EDRs, it might constitute a legitimate concern for some citizens even though their travel is undertaken in a public place.

Therefore, a primary objective of organizational EDR policy should be to define the EDR. This definition should be kept broad enough to be inclusive of any EDR technology that an agency might utilize, including both ACM and ECM systems.

However, any EDR policy should by definition exclude STS. Issues surrounding tracking systems such as On-Star, Nextel GPS equipped phones, Qualcomm, or any other STS should be dealt with separately, in conjunction with knowledgeable council. A definition such as the one used in this paper would be inclusive of all EDRs, but exclusive of STS.

presented to the prosecuting attorney.

Without specific legislation, the ultimate decision of what circumstances trigger an EDR download will be left up to the local police chiefs, sheriffs, and directors of public safety, who must be assumed to be educated professionals in

The policy should clearly state when a download will be conducted. The second largest concern noted in Kowalick’s research is misuse of EDR technology by authorities (police, insurers, etc). A similar

the purposes of intimidation, intrusion, or coercion.

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For settlement of damages and liability cases, data evaluation is unrestrictedly possible...For criminal proceedings, data are only to be used for accidents resulting in serious physical injuries or death, as well as insurance fraud.

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The specific circumstances necessitating a download of EDR data will be dependent on agency resources and might vary from reading EDR data after any reportable collision to reading data only after serious injury or fatal accidents, or those where fraud or false reporting is suspected.

An agency that chooses to limit EDR downloads to only those cases where criminal prosecution is anticipated must be cognizant of the fact that some EDR data are perishable and subject to being over-written or erased. In some cases this may occur before it is apparent that a case will be

their field. However, when considering what is right for the individual agency, the decision of the German Traffic Court Conference should be kept in mind. As reported by SchmidtCotta, the conference ruled that:

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“The policy should clearly establish training guidelines to promote the highest likelihood of quality data analysis”

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concern was also noted by the Transportation Research Board focus groups, specifically with regard to “targeting” minority groups. A policy clearly stating the circumstances under which an ECM download will be conducted creates a transparent system and reduces the appearance that this investigative tool is being used simply for

It is suggested that the chief administrator who chooses a more aggressive path than that espoused by the German Traffic Court Conference should Collision 63

Similarly, the policy should acknowledge that the CDR Tool Collision 64

Meaningful questions exist regarding the reading of EDR data. These questions will be answered differently in different jurisdictions, due to varying judicial interpretations of the law. Questions such as: when a warrant must be obtained; what constitutes “probable cause” for a search; whether reading the EDR is analogous to inspecting bulb filaments; and so on will be answered differently in different courts. Agencies must be aware of the prevailing legal opinions in their area and must write policy that will, when adhered to, result in favorable evidentiary decisions. It is recommended that agency representatives seek the council of an appropriate prosecutor or corporate attorney when answering procedural questions regarding EDR data.

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EDR technology is simply another tool for the crash investigator or researcher. As such, any policy addressing EDRs should remain as similar to existing agency or corporate standard operating procedures as possible. Law enforcement, insurance agencies and others who routinely investigate crashes should already have standard procedures in place whereby the various steps in an accident investigation or reconstruction are carried out. Reading and interpreting EDR data should be included in these normal steps to minimize the potential for oversight and error.

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Agencies serving multiple court jurisdictions should create policy that will fulfill the most stringent legal requirements of their jurisdictions to avoid adverse evidentiary decisions. In addition, agencies in states that have enacted EDR legislation should review these new laws thoroughly with competent legal council. A simple reading of

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EDR policy must be consistent with federal, state, and local regulations. In order to write meaningful policy, every agency must seek advice from those who are knowledgeable regarding the rules of evidence and rules of criminal and/or civil procedure

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The policy should clearly establish training guidelines to promote the highest likelihood of quality data analysis.

Agencies using the Vetronix CDR Tool should differentiate between those who are qualified as “operators” and those who are qualified as “analysts.” These qualifications should be based exclusively upon completion of the appropriate certification 6. level taught by an approved agency that is endorsed by the Vetronix Corporation and the automobile manufacturers.

in its jurisdiction. EDR policy must comply with traditional search and seizure law rulings as they are applied in the court of primary jurisdiction. In the US, expertise in reading and analyzing EDRs will be governed by either the Federal Rules of Evidence 701-703, or by the Frye Standard, and ultimately by the local judges’ interpretation of their meaning.

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is a rapidly evolving instrument as new vehicle manufacturers begin to comply with the US Department of Transportation’s recommendation to make ACM data accessible by 2008. In the opinion of the author, refresher training and continuing education in the EDR field is more important than in the traditional areas of accident reconstruction. Since 2001, far less has changed in the application of Newtonian mechanics than in the field of EDR availability and accessibility. Policy must not merely allow for but must require continued education of EDR operators (particularly in the CDR Tool area).

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The policy should specify that only those who are trained and officially certified as analysts, operators, or technicians should conduct the physical reading of the EDR module, and only those qualified as “analysts” should be responsible for interpreting the data. The primary benefit of this is that it will promote 5. the acceptance of the data in judicial or administrative settings. Additionally, such a specification encourages the agency or company to keep trained and officially qualified employees. ra

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seriously consider if this is a level of EDR use that his/her constituency will bear. However, even such an aggressive policy of EDR use may be acceptable as long as a policy applies fairly and consistently to all motorists, and there is no perception that the EDR is being used to single out or harass a demographic group.

promulgated by organizations such as the American Society for Testing and Materials (ASTM), the International Association of Chiefs of Police (IACP), the Society of Automotive Engineers

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“EDR policy must be consistent with federal, state, and local regulations”

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When the EDR is used in an internal investigation, employees should be afforded the same benefit as non-employees.

Data should be read and analyzed only by trained and certified technicians. As with external investigations, internal investigations should employ EDR reading by a standard guideline according to agency

These eight items can be contained in a brief document. The policy writer should be advised that top-down micromanagement of employees is not a goal of creating policy. Effective policy provides clear directives but does not seek to address every scenario that could conceivably occur. Those writing EDR policy would do well to heed the advice often attributed to Robert E. Lee: “Make no unnecessary rules.” This is of particular importance due to the ongoing evolution of EDR technology and the reaction to EDR usage by the courts and governments, on the federal, state and local level.

Agencies need to be cognizant of the fact that once an EDR policy has been written, it may have to be modified to adapt to future interpretations or reinterpretations of the law as applied to EDRs. Subjecting the policy to excessive “rulification” can be expected to significantly increase the chance of re-writing an existing policy.

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Organizational EDR policy should aim to maximize consistency with related guidelines offered by respected organizations.

Those who are creating EDR policy must remember that the EDR manufacturer is the ultimate authority on its own product; EDR policy must be consistent with the instructions taught in certification classes, regardless of the input of other organizations.

However, in any instance where there is not a direct conflict, standards

If the EDR may be used in internal investigations into an employee’s driving at the time of an event, it is wise (though not legally necessary in most cases) to inform the employee that his or her vehicle contains an EDR and that it is subject to search after an accident. One of the largest potential benefits to EDR use is a reduction in accident and damage rates, such as that seen in the European Union. If vehicle operators are unaware of the presence of an EDR, some of this benefit will be lost.

manpower and ability. Given the litigious nature of our culture, some agencies may find it worthwhile to read EDR data after almost any reportable motor vehicle accident.

Although every agency should perform its own cost-benefit analysis and evaluate its capabilities when considering reading employee EDR data, a single standard should be used consistently to determine if EDR data will be read and analyzed. This standard should be followed strictly.

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(SAE), or the Department of Justice (DOJ) should be considered and incorporated into organizational EDR policy. At present, the final standard of the ASTM on EDR technology has not been released to the public.

Although compliance with such a standard is completely voluntary, it will be wise for organizational policy makers in all areas of crash investigation to become familiar with it.

No policy should seek to manage every aspect of an employee’s job, duplicate existing policies, or replace first-line supervisors. For example, if policy is in place requiring employees to take proper care of equipment, there should be no need to specify

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the text of these new laws seems to indicate that the laws have altered traditional abilities of law enforcement to conduct vehicle searches of the EDR data based on probable cause. Whether or not this is the intent of the legislatures will be determined by case law. Until a clear decision is made in each of these states, law enforcement officers should confer closely with the state’s attorney regarding the appropriate means of obtaining EDR data.

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However, such generic documents and standards cannot supersede the applicable state or provincial laws, nor can they be relied upon to sway a judge who disagrees with the documents or interprets the law differently. As with other proposed standards or model policies, if a conflict exists between the model and the official sanctioned training of an EDR manufacturer, this conflict should always be resolved in favor of the officially sanctioned training.

No “model computer seizure policy” can possibly address the particulars of each EDR, especially as the technology grows and changes.

Following any generic “guideline” or recommendation at the expense of product-specific technical training may have disastrous evidentiary implications.

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anyone conducting a download be appropriately certified and follow the correct procedures taught during the certification process.

Further clarification of the process, if necessary, should come from knowledgeable, certified first-line Another potential pitfall in EDR supervisors, who may address specific policy involves creating policies procedural issues. and procedures that will be quickly outdated. There are many technological The IACP has presented model issues concerning EDRs that are not policy on vehicle search and seizure, mirrored in other aspects of accident and the USDOJ has offered a lengthy investigation / reconstruction. The manual titled Searching and Seizing policy and procedure manual should Computers and Obtaining Electronic not seek to replicate or replace a Evidence in Criminal Investigations. manufacturer’s training program. It Both of these documents provide the is not the proper venue for providing policy maker with helpful suggestions specific instructions on the process for obtaining the best evidence and of conducting an EDR download. contain applicable issues to EDR A policy manual should require that data seizure for law enforcement. that the CDR Tool kit be kept in a specific box, under lock and key in a specific locker. If required at all, such orders should be adequately dealt with by verbal direction from a firstline supervisor.

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HE AUTHOR

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William Messerschmidt is a former police accident reconstructionist.

He earned a Bachelors degree in Economics at Auburn University and Master of Public Administration at Columbus State University. He is a certified user of the several EDR reading systems, CKNOWLEDGEMENTS including the Vetronix CDR Tool.

Mr. Messerschmidt is employed as The author would like to a collision reconstructionist and extend his appreciation safety consultant with Robinson & to the following individuals whose Associates in Birmingham, AL. He timely and thorough assistance can be reached at: made this paper possible: Dr. Peter wfm1372@charter.net.

Rutledge, Mr. C. Gregory Russell,

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Lt. Thomas W. Carswell, and Ms. Kelly S. Messerschmidt.

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EDR technology is poorly understood by the general public, and the debates surrounding access to the data EDRs contain have been cast in terms of “safety versus privacy.” Many common beliefs about EDR technology simply do not apply to items such as the Vetronix CDR Tool, Caterpillar Electronic Technician (CAT ET), Detroit Diesel Diagnostic Link (DDDL), or Cummins PowerSpec Reports. In spite of the inaccuracies of public opinion, legislation has been and is being developed that limits the access of police, hospitals, insurers, and researchers to EDR data. In order for public (legislative) policy to be

“informed by the best evidence,” the law enforcement, scientific, and traffic safety communities will need to build strong coalitions, provide accurate information to legislators and the public, show competence with this new technology, and demonstrate a judicious and equitable approach to its implementation. One important step in this process will be the creation of fair, effective organizational policy

by EDR users.

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ONCLUSION

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Practical Aspects of Crash Data Retrieval Using the Vetronix System

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This paper was written to discuss practical issues for those who may be considering adoption of the Vetronix CDR technology, and provides some management background for those who already have. A decision to become a service provider for this new technology should be made based on consideration of all the costs and commitment required. The cost of adoption of the technology includes not only the direct monetary costs of NTRODUCTION the equipment, ancillary tools, trainMany ACMs write data to ing, hardware and software upgrades, an electronic file in the event but also the in-house labor costs reof a deployment or near-deployment quired to obtain and maintain techof the frontal airbags. Retrieval of nical proficiency. this data can be accomplished using dedicated hardware and software, and this process has come to be known 00

Many airbag control modules (ACMs) write data to an electronic file in the event of a deployment or near-deployment of the frontal airbags. Retrieval of this data can be accomplished using dedicated hardware and software, and this process has come to be known as “Crash Data Retrieval” or CDR. CDR is performed as one component of the reconstruction of a motor vehicle incident. The retrieved data can only be understood and/or interpreted properly when viewed in conjunction with the physical evidence, setting, and environment used to reconstruct the incident. The only way to verify the data obtained via CDR is to compare it against the actual physical evidence and the results from conventional solution techniques, and this can only occur at a point in the reconstruction process when the conventional reconstruction efforts are completed or substantially so. When such an approach is used, CDR becomes another tool in the kit for accident reconstruction, and both compliments and expands the capabilities of conventional reconstruction techniques.

The initial costs include the expense

as “Crash Data Retrieval” or CDR. The Vetronix Corporation of Santa Barbara, California, manufactures and sells the only publicly-available equipment for retrieval of crash data from ACMs in General Motors, Ford, and limited models of Isuzu and Saab vehicles. The list of automobile manufacturers that can be accessed using the Vetronix equipment is expected to expand in the near future, and to continue expanding over time.

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of the Vetronix CDR kit, ancillary tools, formal training, and overhead/ administrative costs. With regards to CDR technology, formal training is not an option; it should be viewed as a mandatory part of the “commitment” required to institute this service. In addition to the Vetronix kit, additional equipment is required to access the ACM and conduct a download, and a list of equipment is presented.

The initial costs and continuing costs to acquire the equipment and develop and maintain technical expertise are discussed. Most technical support is provided via an online forum, and the operation of this forum is discussed. Management options that may help reduce the cost of participating in CDR are discussed. Finally, miscellaneous practical issues based on the author’s experience are also discussed.

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BSTRACT

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In order to make such a comparison, the “Momentum Calculations” task must be completed prior to the “CDR Analysis” task. Any discrepancies between the CDR data and the physical data, conventional calculations, and conventional analysis approaches, must be understood and explained.

Such comparison cannot occur until late in the process when the conventional analyses have been completed.

Data obtained via CDR has known limitations, and these limitations vary dependent on the particular ACM in-

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understood through knowledge of the physical evidence obtained from examination of the scene. Therefore, the “Examine Scene” task should be accomplished prior to undertaking the “CDR Analysis” task. For example; if the CDR data indicates that an emergency brake application occurred prior to impact, then one should be able to correlate that with tire marks that were visible at the scene. Continuing this thought process; if the CDR indicates that seat belts were in use during a highspeed collision, one should be able to verify such from the examination of the seat belts that occurred during the “Examine Vehicle” task. Pre-impact speed calculated using a momentum analysis should agree reasonably well with the pre-impact speed indicated by the CDR.

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reconstruction of a motor vehicle incident. The retrieved data can only be understood and/or interpreted properly when viewed in conjunction with the physical evidence, setting, and environment used to reconstruct the incident. CDR should not be used to provide stand-alone answers regarding a motor vehicle collision incident without consideration of the physical evidence, setting, and environment associated with the incident.

Fig. 1 below is a simplified project management plan for reconstruction of a motor vehicle incident. In project management terms, Fig. 1 is referred to as a Network Analysis because it shows the path through the network from beginning to completion of the project. The fieldwork for CDR can logically be accomplished at the same time as the “Examine Vehicle” task, and therefore is shown in the diagram as a subpart of that task. Analysis and interpretation of the CDR data Following sections of this paper dis- should be done at a later time in the cuss the role of CDR, the initial cost office, as shown (Fig. 1). and commitment to implement CDR services, the annual cost and com- The “CDR Analysis” task should ocmitment required to maintain CDR cur at some late point in the network, capability, considerations for large or- after other field tasks and office analyganizations, economic payoff, miscel- ses are complete. This task includes laneous issues, and conclusions. evaluation and interpretation of the retrieved data, and any calculations The Role of CDR in a Collision Re- performed using that data. Pre-colconstruction Project. CDR is per- lision braking data as indicated by formed as one component of the the CDR can only be evaluated and

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he Vetronix CDR technology is continuously evolving as new automobile manufacturers and model years are added to the program. This evolution and advancement necessitates an ongoing program of hardware and software updates, manufacture and distribution of new connecting cables, and a continuous training program. This is a state-of-the-art program, and successful adoption of the technology requires a commitment by upper management to keep both the equipment and the personnel updated to the current state-of-theart. The level of commitment (both money and labor) required is not trivial, and should be thoroughly evaluated in advance by those considering adoption of the technology. CDR technology is still relatively new, and as with any new technology there is a risk of future obsolescence.

Fig. 1 – Simple Network Analysis of Collision Reconstruction Using Momentum and CDR

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Any program to institute CDR services must of necessity involve a formal training component. Anyone can purchase the CDR equipment, and with a minimum of experimentation most could learn how to perform a basic download. However, a risk of evidence spoilage exists for those who aren’t educated of the pitfalls, and this could prove to be quite costly for anyone operating within the jurisprudence system. Assuming an untrained individual is able to successfully download the data, understanding and interpreting the data is another matter entirely. The CDR software can produce a nicely formatted report of the downloaded data, and this can easily lull the untrained into believing that they have the “answer.” The problem with accepting the CDR report as being correct as shown is that there are numerous anomalies and limitations to the data. Formal training is required to understand and recognize these anomalies and data limitations. The technology is still so new that there are no textbooks or publications that discuss these anomalies. With the rapid pace of change and evolution of the technology, and given the fact that the auto manufacturers use a variety of third-party vendors to supply their ACMs and that each manufacturer may program the ACM to their own proprietary specifications, any textbook would likely be obsolete before it was even published. State laws are being written and modified in response to the existence of this technology, and those who aren’t educated run a real risk of violating the law. With regards to CDR technology, formal training is not an option; it should be viewed as a mandatory part of the “commitment” required to institute this service.

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approach is used, CDR becomes another tool in the kit for accident reconstruction, and both compliments and expands the capabilities of conventional reconstruction techniques.

The above discussion is summarized with the following key points: • CDR is a logical and Efficient Addition to an Otherwise Conventional Collision Reconstruction Project • Final Analysis of the Retrieved Data Should Only be Done Late in the Numerous other tasks might be re- Project After Other Field Work and quired for the reconstruction of any Analyses are Complete particular incident, and the reader can • CDR and Conventional Techniques easily envision additional items placed are Complimentary Methods That in Fig. 1. The tasks shown in Fig. 1 Increase the Validity of the Reconare intended to illustrate the point struction that CDR is only one portion of the • CDR is NOT a Stand-Alone techoverall work effort required to recon- nology struct the incident. For individuals or firms that already practice in the field Initial Costs and Commitment: of collision reconstruction, CDR is a The initial costs include the expense logical addition to their portfolio of of the Vetronix CDR kit, ancillary services. Others considering offer- tools, formal training, and overhead/ ing CDR services should be aware administrative costs. Senior-level that they will be providing only one management should be informed and component of the total effort need- must be supportive of the intention ed to understand and reconstruct a to institute CDR services. Unless motor vehicle incident, and that the management is committed to providretrieved data may not constitute a ing not only the initial costs but also complete rendition of the incident. the future year costs of maintaining CDR data can be misleading when the system and personnel, the effort used as a stand-alone source to recon- will most likely fail. struct a motor vehicle incident. As a simple example, consider that many The Vetronix kit itself is sold for a reACMs record pre-collision speeds tail price of $2595 by the manufacthat can be retrieved using the CDR turer, and consists of a plastic case that equipment. Environmental condi- houses the translator hardware and a tions such as icing or heavy rain can variety of cables that allow hookup to result in a speed being recorded that is a diagnostic link connector (DLC) higher than the actual vehicle speed, port or directly to the ACM of supwhile yawing or rotating vehicles may ported vehicles. Additional equiprecord speeds that are less than the ment is needed, including a field actual vehicle speed. CDR results portable computer, and must be proshould be compared to an analysis vided separately by the user. Vetronix using conventional reconstruction Sales Agents are authorized to offer a techniques to best understand and $200 discount on the retail price of evaluate the incident. When such an the equipment.

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volved. Power loss may occur during a collision and this can affect the data obtained via CDR. The only way to verify the data obtained via CDR is to compare it against the actual physical evidence and the results from conventional solution techniques, and this can only occur at a point in the process when the conventional reconstruction efforts are completed or substantially so.

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the computer, and protects it from dust, sunshine, and rain.

4.

Data Storage & Backup Devices. An immediate backup provides insurance against loss of the data, and also allows for sharing the data onsite with others. Numerous options exist for backup; if the portable computer does not have a backup capability, the reader is advised to purchase some form of backup that can be used in field conditions.

5.

Flashlight. Useful for viewing beneath the dash and seats. Get a good one that uses several D-cells, or a light powered by 12 volt from your own vehicle or a portable source.

6.

Inspection Mirror. A mirror mounted on an extendable handle can help you peek under the dash to locate the DLC port, or view beneath a seat. This can be extremely helpful if the collision has displaced the dash backwards and there is little or no room between the dash and the seat.

7.

Tarps. An 8X10 tarp folded twice to form a 4X5 surface is just the right size to provide a place to kneel beside a vehicle and a clean surface to place the CDR kit and other tools.

Another tarp can be draped over the driver’s seat and into the floorboard to cover glass, other debris, blood stains, etc.

8.

12-Volt Extension Cord. The CDR kit includes an 8-foot cord to connect the unit to a 12-volt power outlet. Sometimes that just isn’t long enough, so purchase a 12-volt extension cord.

9.

Jumper Cables. Purchase the longest set of 12-volt jumper cables you can find. In a salvage yard or wrecker yard you may find that the collision vehicle is not easily accessible and you may not be able to park your vehicle as close as you would prefer.

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Training for the retrieval and analy- technology. The amount of adminissis of crash data is certified by and trative and/or overhead costs required through the Vetronix Corporation. (if any) is a function of the policy of An individual can acquire a certificate the particular firm or agency. at the “Technician” level by attending a 1-day course, and can be certified Ancillary equipment is required to at the “Analyst” level by attending operate the CDR gear and download a subsequent 3-day course. Both data from vehicle ACMs. The CDR courses require successful comple- kit contains only the hardware and tion of a written exam as part of the software required to connect a comcertification requirement. As of this puter to the vehicle’s DLC or ACM. writing, the Collision Safety Institute Some additional equipment is re(CSI) is the only vendor that has been quired, and some optional tools can approved by the Vetronix Corpora- aid with troublesome situations that tion to teach both courses. Com- occur in the field. The bulk of addimencing in late February of 2006, tional tools and equipment that may other vendors are expected to be cer- be needed are required to facilitate actified to teach the 1-day Technician cess to the ACM. The ACM is often course. The current cost of the train- located under a seat or under and/or ing is $150 for the Technician course behind the console, and sometimes and $300 for the Analyst course, or requires considerable effort to access. $450 for both. Travel, lodging, and Following is a list and brief discusper diem is not sion of tools and included in the “With regards to CDR equipment that training costs. technology, formal train- may be needed in addition to Administrative ing is not an option; it the Vetronix and overhead should be viewed as a CDR kit: costs include 1. P o r t a b l e mandatory part of the the staff supComputer.

A port required to “commitment” required notebook or laptop computer is purchase, place to institute this service” required.

The into inventory, and secure the equipment in storage. unit must have a Police agencies and large consulting serial communication port, or an firms may require that a Standard adapter is required to allow hookup Operating Procedure (SOP) be de- of the serial cable into a Uniform Seveloped regarding the assignment, rial Bus (USB) port.

Portable Computer Power usage, and storage of the equipment. 2.

Ancillary tools and equipment may Source. The actual CDR download also need to be purchased, placed into itself takes very little inventory, and stored. Some firms time, so most users will be accomor agencies may consider the cost of modated quite well by the computtraining as an overhead or adminis- er’s own battery. However, you may trative item, while others may have wish to invest in an auxiliary cable to a line item for training. Regardless power the computer using a 12-volt of the accounting vagaries, training power outlet.

Portable Computer Bag. The should be included when determining 3. the initial cost of implementing this bag provides a cushioned support for Collision 72

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offset or “S”-shape wrenches, vertical offset wrenches, and breaker bars have proven useful.

18.

Penetrating Oil. Useful for removing rusted nuts.

19.

Reciprocating Saw. There are portable units powered by battery pack, but this tool will consume a lot of power, so battery life may be inadequate. The use of an inverter or a portable generator for electrical power may be a more practical alternative.

20.

Inverter. For substantial power tools such as a reciprocating saw, a minimum 700-watt inverter will be required.

21.

Screw Drivers. Drivers are needed for a multitude of screw heads including straight, phillips, torx, hex, and square.

22.

Hammer. A small sledgehammer or medium ball pen hammer can be useful for gaining access to ACMs

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module is often located underneath a seat, beneath the insulation and carpet. To access the module, you have to remove some of the carpet and insulation.

15.

Scissors. Similar in use to the utility knife mentioned above, scissors are more practical for removing the insulation and cutting off excess carpet strips.

16.

Wire Cutter/Stripper. Common wire pliers are useful, but an electrical wire stripper/crimper tool is better. Needle nose pliers are useful for working with smaller diameter automotive wiring.

17.

Wrenches & Sockets. Wrenches and/or sockets will be needed if the ACM is to be removed, or if it is necessary to remove a seat. A variety of tools including deep sockets, external torx sockets (size E20 and smaller), snub-nose flex-head ratchets, socket u-joints and extenders, horizontal

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Portable 12-Volt Power Packs.

Two of these are optimum, as one can provide a power source for a dead vehicle battery and the other can provide power for the CDR equipment.

11.

Fuse Powering Kit. A device made to power some vehicle ACMs directly through the fuse box. Allows downloads to occur without generating the Diagnostic Trouble Codes (DTCs) that would be present from a direct to ACM hookup in certain vehicles.

12.

Pry Bar. To assist with opening a pinched or crushed hood to allow access to the battery, or for use to facilitate access to the ACM inside the vehicle.

13.

Knee Pads. When connecting directly to the ACM, knee pads may prove to be one of your most useful accessories, especially when kneeling on a gravel surface.

14.

Utility Knife. The airbag

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inside severely crushed vehicles.

YEAR 1 ITEM APPROXIMATE COST 23.

Bolt Cutter.

Helpful RANGE for egress when cutting directly through a seat and needing to reVetronix CDR Kit $2395 - $2595 move the welded wire supports.

Portable Computer $0 - $2000 24.

Evidence Labels. EviMisc. Tools, Equipment, Supplies $0 - $1000 dence labels help to clearly estabTraining Fee $450 - $1200 lish the initial chain-of-custody Training Travel, Lodging, & Per Diem $0 - $1300 in the event an ACM must be reOverhead & Administrative $0 - $2000 moved from the vehicle.

25.

Latex Gloves. These are TOTAL $2845 - $10,095 cheap and very strong, and you can easily handle tools with them Table 1. Approximate First-Year Cost to Establish CDR Services. on. They provide protection from bio-hazards that may exist in the col- additional computer or any of the cost to maintain. Although the Vetrolision vehicle, but your hands will miscellaneous tools discussed, and if nix kit itself should never “wear out,” the training is available locally such routine software updates and hardsweat in them.

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Surface Disinfectant. Hos- that no travel costs are incurred, and ware upgrades will be required as new pital type surface disinfectant can be if the organization only trains 1 indi- manufacturers and vehicle models are purchased in pump-spray bottles. An vidual, and if the organization doesn’t added to the list of those already supexample of one such product is Envi- require accounting for administrative ported. The cost of these upgrades rocide, which is labeled to kill bacte- or overhead costs, then approximate- can be estimated as an annual amria, viruses, fungi, and other undesir- ly $3,000 is sufficient to implement ortized cost. If a portable computer ables including tuberculosis and the CDR services. This is obviously a is dedicated for use only by this sysminimalist estimate, and most orga- tem, then the entire replacement cost HIV virus.

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Antiseptic Hand Cleaners. nizations should anticipate a greater should be estimated as an annual amThese products are used for cleanup cost during the first year. However, ortized cost. However, if the computafterwards and kill a broad spectrum very few organizations will require the er is used for other tasks, then only a of germs. An example of one such approximately $10,000 conservative- portion of its value should be considproduct is Vionex, and it is available ly estimated for the upper end. With ered when estimating ongoing costs. as a lotion or as a towelette. No water regards to training, the high estimate Miscellaneous tools, equipment, and is required with this product, which column assumes that an organization supplies will likely be required to supis a definite advantage in field condi- sends 1 individual through the Ana- port the ongoing operations. Formal lyst level of training (and has travel training will need to be re-taken peritions. expenses) and sends 5 others to the odically to maintain expertise, and/or Some of the listed tools are items that Technician training (with no travel to educate new personnel. Due to you probably already have in your costs). Cost accounting methods will the ever-changing nature of this tech“Reconstruction Toolkit.” The list is vary greatly among organizations, nology, a continuing education proalso a useful aid to help the reader un- and each organization’s situation will gram is needed to maintain expertise derstand the type of work required to likely be different with respect to the between the formal training classes. provide access for connecting to and number of personnel to be trained. All of these activities will incur some However, Table 1 and the discussion expense, either directly or indirectly reading a vehicle’s ACM. preceding it can be used as a basis for in the form of personnel labor.

Table 1 below is an approximation individual organizations to prepare Hardware and software upgrades are of the costs required to implement their own cost estimate. routinely implemented as new manuCDR services during the first year of Out-Year Costs and Commitment. facturers and vehicle models are addoperation.

Most of the items mentioned in Table ed to the program. These upgrades If it’s not necessary to purchase an 1 above will require some continuing must be purchased for the user(s) to Collision 74

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stay current. A CDR file that had previously been retrieved and opened using an older version of the software may appear differently and may contain different information when opened with the latest version of the software. Bug fixes and improvements are included in the software upgrades, so it is important that only the latest version of the software be used to open files and produce reports. This is especially imperative for downloads that may be used in the jurisprudence system. Organizations planning to implement a CDR service should understand that routine upgrades must be purchased to maintain their systems. While this isn’t a requirement of the Vetronix Corporation, it is a practical necessity and constitutes another “commitment” that should be understood by management prior to initial purchase.

2005, approximately 700 users were members of the forum. Members of the forum receive all emails sent by other members of the forum. As new issues and situations are identified by users, they are discussed by members of the forum. Members are able to post files to the group website so that others can review them and offer opinions. The forum is an indispensable tool for users of the CDR system and allows practitioners to stay knowledgeable between formal training sessions. During the course of an average week, Analyst-level users should plan on spending a minimum of 1 hour reviewing the forum emails and/or participating directly in the technical support issues. Management should commit to allowing emMost of the support for users of the ployees certified at the Analyst level CDR system is provided via mem- to have sufficient time to participate bership in the CDRtool online fo- in the forum. While this may seem rum. The forum website is located like an “extra” commitment, it is simat www.CDRtool/yahoogroups.com ply part of the ongoing commitment and membership is only available to to maintain the proficiency of practithose who have completed a Vetro- tioners. Unless the user participates nix-approved Analyst-level certifica- in the forum, the proficiency and tion training course. As of December understanding acquired at the forAs more manufacturers and vehicle models are added, the number and variety of ACMs supported will increase, and the frequency of hardware and software updates is likely to increase; therefore, the annualized price of upgrades will likely increase. The initial purchase price of the system has increased to $2595 from the original cost of $2495, and it too will likely increase as more capability is incorporated into the system and more cables are included with the system. Users who initially purchased the system and have purchased the subsequent upgrades have incurred $3780 in expense for the system as of February 2006. Additional upgrades are likely to occur later in 2006.

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$ Dollars $

To date, there have been 3 upgrades to the initial hardware/software that users were required to purchase. Numerous other software updates were made at no cost to users. Hardware upgrades have primarily consisted of the addition of new Initial Purchase 3000 cables for direct connection to the ACMs 2500 of newly supported Other Potential 2006 Updates; vehicles. The original 2000 New OEM Update? version of the translator box has also been Ford/GM Update?

1500 upgraded twice. Fig. 1000 2 depicts the chronology and cost of ownGM/Ford Updates CAN Update 500 ership of the Vetronix system to date. To 0 date, the upgrade 2000 2001 2002 2003 2004 2005 2006 costs have averaged GM Ford/Isuzu Other OEM? Saab Year about $260 per year when spread over the Figure 2. Chronology and Cost of Ownership of the Vetronix CDR System 5 year history of the system.

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mal training course will quickly be outdated. Due to the constant acquisition of knowledge from testing of new supported vehicles, the formal training materials are continuously updated. Participation in the forum is the “link” that maintains proficiency between formal training sessions.

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1 The formal training materials are continuously updated to account for 0 the addition of new manufacturers 2000 2001 2002 2003 2004 2005 2006 and vehicle models. Users should Ford/Isuzu Other OEM? GM Saab Year plan on periodic updating of their Fig. 3 CDR Training Requirements History. formal training via refresher courses, or by simply retaking the (current) of SOPs, personnel supervision, and order of $1000 to $4000, depending training course. A 3-year period bethe overhead costs for purchase of on the accounting requirements of tween formal training courses may be upgrades and training. It is difficult the particular business or agency. optimum, providing the user mainHall to Consulting, estimateP.L.L.C. this cost, but it should be tains an active participation in the less that the initial effort during the Management Considerations and online forum. Management should first year of operation.

Options. The initial cost and ongobe aware and committed to providing ing costs of ownership of the CDR periodic formal training for users of Cost accounting methods will vary system are not trivial. However, the the CDR system, especially those cergreatly among organizations, and retrieved data provides a significant tified at the Analyst level. The length each organization’s situation will advantage in reconstructing an inof the training has increased since the likely be different with respect to the cident, and this advantage will only system was first introduced, a necesnumber of personnel trained. How- increase as the technology evolves sity as additional OEMs and vehicle ever, Table 2 and and more parameters are recorded. models become “This approach can the discussion pre- Management options that may help part of the proceding it can be reduce the cost of participating in gram. Figure 3 maximize the potential used as a basis for CDR include the following; below shows the individual organitraining increase for retrieving collision zations to prepare 1.) outsource the retrieval and the from 2000 data by the field offi- their own cost es- analysis of the data, through 2006. timate. Note that 2.) retrieve the data using in-house Note that un- cers, while saving funds labor cost for par- personnel and equipment, and outcertainty is indi- by training a relatively ticipation in the source the analysis, and cated for 2006 as CDRtool forum 3.) provide most personnel with the the anticipated smaller number at the is mentioned in Technician training and provide a addition of anAnalyst level” Table 2, but was lesser number with the Analyst trainother OEM may not included in the estimate; organi- ing. result in an increase of the training zations should decide for themselves necessary for the Analyst level. Some if and how to best consider such costs. The first option listed above requires organizations may require accounting Considering the uncertainties in this no investment in equipment, trainfor overhead as part of the ongoing estimate, it is reasonable to assume ing, or upgrades. However, outsourccosts of operation. Activities that may that the annual cost to maintain both ing may cost more on a unit basis be classified as overhead could consist the system and personnel is on the than for in-house personnel, and the of development and annual review Collision 76

Economic Analysis. Any attempt at computing a payoff or break-even point will depend on organization specific input, and as such can’t be definitively analyzed herein. However, the underlying considerations that form the backbone of such analyses can be discussed.

The field time required to download an ACM is dependent on the ease with which the connection can be established; if the vehicle has battery power and the ACM can be accessed via the DLC port, it is relatively fast; but if there is no battery power and the vehicle is severely crushed such that a direct to ACM connection must be made, it is relatively slow.

One hour is a reasonable time to as-

$500

Portable Computer

$0

- $200

Misc. Tools, Equipment, Supplies

$0

- $100

Training Fee

$100

Training Travel, Lodging, & Per Diem

$0

Overhead & Administrative

$0

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AMORTIZED ANNUAL COST ESTIMATE

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OUTYEAR ITEM

- $450 - $1000

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The final option listed above is most applicable to larger organizations.

For example, a large police agency may wish to train a relatively high percentage of the traffic enforcement officers to the Technician level, and only train a few to the Analyst level. This approach can maximize the potential for retrieving collision data by the field officers, while saving funds by training a relatively smaller number at the Analyst level. This approach has the potential for an even greater cost savings; because there are expected to be many vendors who can provide the Technician training,

Another consideration for larger organizations involves the number of Vetronix kits to purchase. Since the equipment isn’t used on a full-time basis, a certain number of personnel can share each kit. Geographic distance must be considered, as there is a practical limitation on the ability to transport equipment between locations. Although it is possible to remove the ACM and ship it to a centralized location for bench downloading, this is not a recommended practice. In addition to the chain-ofcustody concerns, some ACMs will record DTCs when this approach is used that would not be recorded otherwise. Providing a kit for each

user is perhaps the optimum approach, albeit the most costly. Police agencies may wish to institute sharing of the kits between the day and night shifts, or simply store the equipment at field or district offices for retrieval as needed.

CDRtool Forum Participation (assume 1 hour/week) TOTAL

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The second listed option may be a good approach for organizations such as insurance companies who may wish to equip field personnel with the capability to download the data, but don’t have the need to maintain expertise at the Analyst level. This approach may be particularly well suited if the organization usually contracts with others to provide the reconstruction of the incident, as the CDR analysis and event reconstruction are intrinsically connected.

it is probable that this training could be offered locally and travel expenses wouldn’t be incurred by the relatively large number of officers that receive the Technician training. As an example, a police agency may elect to provide Analyst-level training to only 1 of every 5 officers trained at the Technician level.

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organization will be dependent on the availability and schedule of the contract service provider. The economics of this consideration are obviously dependent on the number of cases wherein the organization may reasonable anticipate a need for CDR. This is certainly the most convenient way to ease into the CDR technology, and may be preferable for small police departments, insurance companies, or prosecutors who need to employ an independent expert for criminal matters. A listing of service providers is maintained by Jim Harris of Harris Technical Services, and can be accessed at http://www.harristechnical. com/cdr.htm.

50 hours/year labor cost $?? +$600 - +$2350

Table 2. Approximate First-Year Cost to Establish CDR Services

Collision 77

sume for the “average” download.

The time involved for the analysis/ interpretation phase is dependent on the complexity of the data as well as the complexity of the overall incident reconstruction. As previously discussed, the analysis/interpretation phase is intricately related to the overall incident reconstruction to such a degree that the two really can’t be separated. Approximately 1 to 4 hours of additional time may be required to reconstruct an incident with CDR involved as compared to one without.

Therefore, it is reasonable to assume that 2 to 5 hours of additional billing time may accrue for private consultants or engineering firms.

mately $200 is billed to clients when the CDR equipment is used on a case. This fee is charged in addition to labor fees, mileage, and other common fees such as photographs.

For insurance companies, the data contained in a CDR download can be instrumental in determination of liability, exposure, and decisions to pursue subrogation. The fact that the data exists is cause for the insurer to obtain it as part of their duty to defend. Failure to obtain and analyze the data could very well be interpreted as negligence that indicates bad faith. Some state laws now specifically prohibit insurers from being able

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For private entities, a break-even economic analysis could be performed based on a comparison of the previously discussed initial costs and ongoing annual costs versus the expected additional income from equipment fees and additional labor. However, such an analysis is overly conservative because it does not take into account additional cases that may be acquired by the firm due to this (CDR) capability. For any such new cases acquired, the entire net income may be Many private consultants and engi- considered to be additional income neering firms charge an equipment accrued due to possession of CDR fee for the use of the CDR gear. In- capability. formal discussion with other providers indicates that a fee of approxi- For public entities such as police

agencies or highway departments, CDR capability is more difficult to analyze from an economic standpoint. If the agency is large enough such that a substantial number of collision incidents are reconstructed annually, then having an internal CDR capability is inherently justified. If not, the agency can still obtain such services via contract with private service providers.

Fig. 4 Cable Management.

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3. Severely Crushed Vehicles. The problem of access is compounded when the vehicle has undergone severe deformation. In such cases, the only way to access the module may involve cutting via power saws and liberal usage of pry bars. Operators may wish to obtain the help of a professional mechanic for such cases. A novel approach for floor-mounted 6

1. Cable Management. To date, there are some 15 cables that have been developed to access different ACMs. In addition, there are other cables that are used to power the unit (both 12volt and 110-volt versions), interface with the vehicle diagnostic port, and interface with a computer. As additional original equipment manufacturers (OEMs) are involved in the program and as new vehicle models are added, new cables will be required. Management of the cables

2. Modules Located Beneath Power Seats. In the event that a download can’t be done via the vehicle’s diagnostic port (usually due to the lack of vehicle electrical power), the download must be obtained via a direct connection to the ACM. Physically accessing the ACM can be quite challenging in a crushed vehicle. For ACMs located underneath a seat, techniques include cutting a hole through the seat bottom, unbolting and removing the seat, or adjusting the seat in its track so as to have the most advantageous working position. The usual caution is noted with regards to potential destruction of evidence; if the position of the seat is an issue in litigation, then the seat should

00

Miscellaneous Practical Issues: The following miscellaneous issues are based on the author’s experience using the Vetronix system.

can become a logistical problem, as they are similar in appearance. The author stores each cable separately in a plastic bag and affixes a label on the bag so as to identify the individual cable by part number. Fig. 4 below shows 2 cables that are labeled so as to be easily differentiated.

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to perform CDR without permission of the owner, even though the insurer may now own the vehicle as a result of the collision. Because the analysis of the CDR data is so intertwined with reconstruction of the collision incident, insurance companies may wish to contract with private providers for this service.

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Figure 5. Optional Electrical Components Useful for CDR Operations

not be moved without prior agreement of the parties involved. The remainder of this discussion assumes that permission has been granted to move the seat, or that this is not an issue. If the module is located beneath a power seat and the vehicle doesn’t have electrical power, power can still be provided directly to the power seat so as to be able to adjust it. Figure 5 below shows various components of electrical equipment that are useful for CDR operations. In the center is a portable 12-volt battery, on top is a pair of jumper cables, on bottom is a 12-volt extension cord, and to the right of center is a 12-volt splitter to allow hookup of two 12-volt devices from a single outlet. To the left of center is a simple cable that can be used to provide power to a power seat. The cable consists of a 12-volt plug that can be connected to a portable 12-volt power source, while the output end consists of alligator clips for the positive and negative current flow. The power wires for a power seat are usually routed from underneath the floorboard to the seat servo motor. Locating and cutting this wire bundle provides a way to power the seat via the positive alligator clip connection while the negative alligator clip is grounded to the vehicle. It may also be possible to power the seat by providing power input through the proper fuse in the fuse box.

Collision 79

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ACMs is to cut through the vehicle • police agency policy requirement from underneath.

• concern about future loss of the module 4. Harvesting Modules. The data contained in the ACM is an electronic file Members of the CDRtool user’s group similar to any other computer file. It are sometimes aware of the possibilusually isn’t necessary to harvest the ity that a certain manufacturer may module from the vehicle to obtain be added to the program, and in such the data; the data can be obtained cases may begin to acquire modby connection through the DLC or ules from those vehicles in the hope by direct connection to the module that the data will later be accessible. in the vehicle. The actual data con- Modules in vehicles that have been sists simply of the electronic file that submerged, or where circumstances is downloaded from the module to have otherwise allowed the module the operator’s computer, and as such to get wet, may be problematic to is similar to any other computer file. download. In such cases, it may be Proper documentation including beneficial to harvest the module and photos and field notes adds validity dry it so as to be able to accomplish to the download procedure and may the download. In the event of a dambe useful in litigation. Removal of aged connection port on the module, the ACM prevents others from hav- it may be possible to later repair the ing access to the information and port in a shop or laboratory setting. being able to “verify” the data inde- Some police agencies have a policy pendently. Additionally, removal of that requires harvesting the module the data causes some modules to set so as to have the “best available eviDTCs that would not otherwise ex- dence.” Such policies should be reist. When such DTCs are set, it may examined in light of the discussion not be possible to verify if these codes above. If a vehicle is slated for imwere set before or after the module mediate salvage, some argue that the was removed, potentially leading to module should be harvested so as to claims of evidence spoliation. The preserve the source of the evidence. difficulty required to harvest a modONCLUSIONS ule varies from moderate to extreme, depending on the location of the The CDR technology is module and the dame to the vehicle. relatively new and is conIf the data can be obtained without harvesting the module, a significant tinuously evolving. CDR and conventional reconstruction methods amount of labor may be saved. are complimentary techniques that In some circumstances, it may be increase the validity of the incident necessary to harvest the ACM. Ex- reconstruction. A serious commitamples of such instances include the ment is required to maintain and update equipment and personnel as the following: technology advances. As with any • vehicles that aren’t currently sup- new technology, there is always a risk ported but may be supported in the of future technology obsolescence, and the faint-of-heart need not apply. future • damaged modules that can’t be read The total up-front costs during the first year can be expected to vary bein the field

tween $3000 and $10000, dependent on factors discussed earlier. Thereafter, the annual cost for maintaining equipment and personnel capability can be expected to vary between $1000 and $4000, again dependent on factors discussed earlier. However, while the cost and commitment required isn’t trivial, the technology can more than pay for itself, both in terms of actual monetary benefits and also in terms of the added service and customer relations. For those professionals who include collision reconstruction in their litany of services, the risk of not offering CDR services may be the greatest risk of all.

Free CDR System training course or a cash rebate when you purchse a Vetronix CDR System through the ARC Network.

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Collision 80

www.cdr-system.com or (866) 223-4984 CDR Training provided by Collision Safety Institute

Resources and Useful Links:

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The following sources may prove useful. The mention of trade names or companies is not an endorsement by the author and is only presented for the convenience of the reader.

-Vetronix Corporation (CDR Equipment) Andrew Bunch, (800) 321-4889 x 3035, 2030 Alameda Padre Serra, Santa Barbara, CA 93130, fax 805-966-9540 http://www.vetronix.com/diagnostics/cdr/index.html -Gazdick Consulting (Fuse Box Power Kit) Bruce Gazdick, Gazdick Consulting, LLC, P.O. Box 16966, Jacksonville, Fl. 32245-6966, phone 904-726-8800, gazdick@bellsouth.net -The Tool Warehouse (Torx Sockets) http://www.thetoolwarehouse.net/ -CDRtool User’s Group (Technical Assistance) www.CDRtool/yahoogroups.com (membership is only available to those who have completed an Analyst-level course) -Collision Safety Institute (CDR Training) http://www.collisionsafety.net/ -Harris Technical Web Site (CDR Service Providers) http://www.harristechnical.com/cdr.htm -Kinderprint (Forensic Supplies). http://www.kinderprint.com/

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Providing affordable lab grade triaxial accelerometers for professional, reliable testing

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The official provider of choice for accelerometers used by the Collision Safety Institute Instrumented Sensor Technology 4704 Moore Street Okemos, MI 48864 USA info@isthq.com Phone:+1 (517) 349-8487

Collision 81

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Motorcycle collinear collisions involving motor vehicles equipped with event data recorders - Roman F. Beck, David A. Casteel, Ed Phillips, Jerry Eubanks, and Doug English

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in a collision. When coupled with vehicle speed sensors, this equipment provides an excellent opportunity to contrast acceleration data collected by the sensing and diagnostic module (SDM). Delphi, Visteon, and other component manufacturers have designed event data recorders (EDR) that are integrated with airbag-related computers on many models of motor vehicles made since 1994 by General Motors, Ford, and other motor vehicle manufacturers. The EDR data often includes the motor vehicle’s

)2

Collinear collisions involving motor vehicles often cause fatal or severe injuries to motorcyclists. The investigation and reconstruction of this type of collision can often be a complicated task because of the difficulties in determining the pre-impact velocity of a motorcycle from the damage to either the motorcycle or the involved motor vehicle. Because of the potentially great disparity in

momentum between the motorcycle and the motor vehicle, determining the change in velocity for the motor vehicle has traditionally been a difficult task in collision reconstruction.

However, modern technology has created an opportunity to simplify this problem. Many current motor vehicles are equipped with airbags and often have an accelerometer and a computer module designed for airbag deployment decision-making. Some of these systems record and store the accelerations that are experienced

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pre-impact velocity and impact change in velocity. Underreporting has been shown to occur as a function of negative acceleration before algorithm enable. Significant underreporting has been suggested to occur as a result of offset impacts with narrow loading. This research paper covers three motorcycle-vehicle instrumented crash tests.

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An additional problem arises when attempting to determine the vehicle’s velocity based on the throw distance of the rider. If the rider sustains a partial or incomplete impact with the vehicle, such as in a collision with the front-end of a low-profile vehicle, then the rider’s throw distance will most likely represent only a percentage of the vehicle’s velocity. This research project has attempted to determine an appropriate range of percentages.

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For this test series, the vehicles used in these three crash tests were a 2002 Chevrolet Cavalier two-door coupe (VIN 1G1JC124827105812, equipped with a 2.2 liter four-cylinder engine and four-wheel anti-lock brakes; 2650 pounds total weight with driver; sensing and diagnostic module [SDM] part number 22674098, service number 22674099, front auxiliary discriminating sensor 16197309 AD7309HC23780) and a 1989 Kawasaki EX500 motorcycle (VIN JKAEXVA13KA024340; 415 pounds total weight). The right front seat was removed to expose the SDM and to facilitate installation of the two accelerometers, which were placed in-line with the SDM (Figure 1). For each crash test, a 160-pound Ogle anthropometric dummy (with a standing height of 5’10”) was placed into a riding position on the seat of the motorcycle, resulting in a total weight of 575 pounds for the motorcyclerider combination. All weights were measured with Haenni Loadometer 20,000-pound scales. Given the resolution of the scales used for weighing the vehicles, the momentum calculations may have an error of about ±10%. The documentation of these tests involved the use of

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results. Hypothetically, a truck with a weight of more than 5000 pounds collides head-on with a motorcycle weighing 500 pounds, including the weight of the operator. Given the collinear nature of this collision, momentum would be conserved, therefore allowing use of the information about the pick-up truck to solve for the unknown speed of the motorcycle. A problem now arises when trying to determine the truck’s ntroduction change in velocity using the damage Historically collision profile because of the extreme weight reconstructionists have relied differential between the two vehicles. on one of two methods to evaluate the A change in velocity of five to ten velocity change that occurs during miles per hour for the truck will result the impact phase of a traffic collision. in a range of 50 to 100 mph for the The first method, momentum, motorcycle. requires detailed information about the vehicles and the scene, including Although determining velocity from approach angles, departure angles, crush in pole and tree impacts can post-impact velocities and vehicle be a difficult task, estimating velocity weights.

The second method, from crush in motorcycles collisions is crush, requires the damage patterns probably much more difficult; given and force deflection characteristics the potential for pre-impact movement for both vehicles. These methods on the part of the motorcycle and have their strengths and weaknesses the separation of the rider(s) from depending upon the amount of the motorcycle, often at maximum information and the type of collision. engagement with the vehicle.

For example, if the collision being Because of these difficulties, the EDR investigated occurred at right angles, presents an opportunity to assess the with both vehicles leaving skid motor vehicle’s change in velocity marks from before impact and to independent of crush measurements. final rest, then momentum would With a known change in velocity from certainly be a strong candidate for the EDR, as well as measurements evaluating the collision. However, in of the principal direction of force the event of a head-on collision with (PDOF), the motorcycle’s change similarly weighted vehicles, analysis in velocity can be calculated using by momentum becomes less accurate the collinear momentum equation. because of difficulties in determining Physical evidence from the scene departure angles. With good crush and the vehicles is especially measurements and reliable data important for determining when indicating how the vehicles translated the rider(s) separated (if ever) from to their final rest positions, it is the motorcycle. This evidence is possible to estimate reliable speed important for determining whether ranges. However, when one of the or not the weight of the rider(s) vehicles is substantially heavier, these should be included in the momentum variables affect the accuracy of the calculation.

Collision 83

the following accelerometer, radar, survey, and camera equipment:

Test 2

Test 3

Farmtek Impact velocity (mph)

11.96

27.21

37.10

Stalker Impact velocity (mph)

12.06

27.79

37.24

IST Average fx during impact (g)

-0.75

-1.82

-3.93

IST Peak fx during impact (g)

-1.70

-6.57

-12.68

IST Peak fy during impact (g)

0.53

3.19

4.22

IST Impact duration (ms)

185.6

180.3

96.2

IST ∆v (mph)

-3.05

-7.22

-8.31

Separation velocity (mph)

8.91

19.99

28.79

SDM ∆v (mph)

n/a

-6.36

-7.78

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Instrumented Sensor Technology (IST) EDR3C tri-axial accelerometer with a range of about 100g, a resolution of about 0.2g, a sampling rate of 3200 hertz, a low-pass filter cut-off of 510 hertz, and 4 megabytes of memory. Per SAE J211, the data was processed in DynaMax 1.4.1 using a 2nd order Butterworth Filter with a lowpass cutoff frequency of 100 hertz.

Test 1

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SDM under-reporting (mph) n/a -0.86 -0.53 An Instrumented Sensor Technology (IST) EDR-6DOF double tri-axial SDM under-reporting (%) n/a 11.94 6.35 accelerometer with a range of about SDM time from algorithm enable to maximum ∆v n/a 180.0 97.5 2.5g, a resolution of about 0.005g, a (ms) sampling rate of 3200 hertz, a lowVelocity at about -1 second before algorithm enable n/a 26 42 pass filter cut-off of 200 hertz, and 4 (mph) megabytes of memory. Per SAE J211, Table 1. Summary of crash test data. the data was processed in DynaMax 1.4.1 using a 2nd order Butterworth positioned upright and stationary at a and can thus differentiate between Filter with a lowpass cutoff frequency set point of impact. The longitudinal lower braking jerk levels from higher of 100 hertz was also employed. centerline of the motorcycle was collision jerk levels. visually lined up with the estimated All CDR data was collected with a approach path of the vehicle. It was Skid Test Vetronix Crash Data Retrieval (CDR) balanced in an upright position and A skid test was performed before System with software version 2.71. steadied. The kickstand was down on the three crash tests. The vehicle was All downloads completed through the the left side of the motorcycle. The accelerated to 40 miles per hour for a Diagnostic Link Connector (DLC). dummy was placed on the motorcycle short distance. Full braking was then in an as normal riding position as its applied in an attempt to lock up the Stalker ATS professional radar gun anatomical structure would allow. In wheels (100% slip). According to (FCC ID IBQACMI001, 33.4-36.0 all three tests there were post-collision the IST EDR-6DOF accelerometer, GHz) with the download software roadway markings left by tires and the vehicle braked at an average drag program Stalker ATS for Windows components. factor of -0.77g, while the Stalker 95, version 4.01 was used to capture radar recorded an average drag factor the vehicle speed. Samples were taken Given the design parameters of of -0.72g (Figure 2). The Stalker value at a rate of 31.25 per second. accelerometer architecture, the IST was used because it is more reliable for and SDM accelerometers conflate all acceleration inputs exceeding 2 or 3 FarmTek Polaris Multi-Event sources of directional input at each seconds. The IST accelerometer data Electronic Timers set three feet time interval and at each axis into a is more appropriate for acceleration apart. single data point. An accelerometer inputs shorter than 0.5 seconds. does not differentiate between ethodology multiple input sources. The airbag Test #1 deployment criteria focus on the rate In all three tests, of change in acceleration (or jerk), In Test #1, the Chevrolet’s impact the motorcycle was

M

Collision 84

speed was about 11.96 miles per hour (Tables 1 through 3).

The impact occurred as the Chevrolet was braking. There was little post-collision displacement of the motorcycle.

As the motorcycle began to acquire the Chevrolet’s speed, the rear tire lifted several inches above the roadway surface, and landed after traveling 18 to 24 inches.

Distance to the right of the Chevrolet’s centerline (feet)

SDM

1.21

Forward Discriminating Sensor

0.42

IST

1.15

Impact #1

1.12

Impact #2

2.00

Impact #3

1.04

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The Chevrolet began braking heavily prior to the impact.

Initial contact was made on the right portion of the front bumper, just below the headlight assembly. During the collision phase, the front wheels came off the ground.

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No information from this test was recorded in the SDM. A pre-existing non-deployment remained recorded in the SDM. The IST data indicated a classic “trough” pattern during the braking phase, including a short and minor negative spike in longitudinal acceleration (Table 1, Figures 8 to 12), but is often substantial enough to result in a recorded non-deployment event.

Test #2

Table 2. Summary of item locations to the right of the Chevrolet’s centerline.

Test 1

Test 2

Test 3

Vehicle post-impact distance (ft)

8.08

29.16

60.54

Ground evidence from motorcycle (ft)

4.6

26.1

79.4

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The motorcycle was positioned and balanced in the same manner as Test #1. The impact point on the car was on the right front corner at a speed of 27.21 miles per hour.

Motorcycle -0.58 -0.59 -0.35 At impact the Chevrolet was in full braking. All four drag factor tires left light but distinct marks on the roadway surface. from ground Non-deployment information from this test was recorded evidence (g) in the SDM (Figures 18 and 19). The SDM recorded a Table 3. Summary of physical evidence and maximum change in velocity of -6.36 miles per hour. separation velocities.

Although the crash pulse was similar in duration to Test #1, the change in velocity was at least twice as great, thus resulted in a recorded non-deployment. The decision to record an event is not based on the recorded speed change, spike in longitudinal acceleration (Table 1, Figures 20 to because the system activates when certain acceleration 24). The IST recorded a change in velocity of -7.22 miles per hour, which is sometimes sufficient to deploy an airbag. levels are met.

As depicted in Figures 22 and 23, the IST and SDM data shared excellent fit. However, the contribution of braking The effects of braking on the overall speed change to the overall change in velocity is significant (Tables 4 and were considered for the heavier, instrumented vehicle. 5). By including a -0.72g baseline correction, the effects Contrasting effects for the lighter, non-instrumented of braking reduce the change in velocity as a function of vehicle will require additional study to specifically the collision pulse to -4.37 miles per hour. Because all determine the effects of contribution of braking through four wheels of the Chevrolet remained on the ground, no calculations were made for the effects of rear-only braking the collision sequence when appropriate. on the collision pulse. The long (180ms) crash pulse is The IST data indicated another “trough” pattern during primarily responsible for the substantial reduction of the the braking phase, including a short and moderate negative change in velocity.

Collision 85

Corrected IST Average fx during impact (g)

-0.52

-3.71

Corrected IST Peak fx during impact (g)

-1.47

-12.45

IST ∆v (mph)

-3.05

-8.31

Contribution of -0.72g to IST ∆v (mph)

-0.92

-0.41

Corrected IST ∆v (mph)

-2.13

-7.90

SDM ∆v (mph)

n/a

-7.78

Contribution of -0.72g to SDM ∆v (mph)

n/a

-0.41

Corrected SDM ∆v (mph)

n/a

-7.37

Corrected motorcycle ∆v (mph), assuming 100% energy exchange

-9.65

-35.79

Table 5. Summary of contribution of rear braking (-0.225g) to overall change in velocity. Test 2 is included because the front axle remained on the ground throughout the collision sequence.

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In comparison, the SDM recorded a maximum speed change of -7.78 miles per hour. The IST data indicated a change in speed of about -8.31 milliseconds prior to impact. miles per hour, which resulted in a 6.4% differential between the In addition, the IST data was applied IST and the SDM. to a formula that is indicated to report Also of interest was the reading of the the “Closing Speed” of two objects: pre-impact speed for the Cavalier from Test #3 at a point of approximately Vc = (DeltaV1(W1+W2))/ W2(1+E) -1 second. The value stored was 42 miles per hour. The Cavalier was Assuming that epsilon (ε, the under aggressive braking and was coefficient of restitution) is zero, this able to easily reach the impact value equation returned a range of closing of 37 miles per hour within the near speeds, depending on the change one-second recording window. The of velocity (Table 6). However, integration of the data would indicate calculations were made to compute ε the Cavalier was at 42 MPH 300- as a function of known data, which are

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Application of conservation of momentum would indicate that the at-impact speed for the Chevrolet was approximately 37 miles per hour based upon the post-collision displacement and the typical or tested-for friction values for the automobile and motorcycle,

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Deployment information from this test was recorded in the SDM (Figures 31 and 32). The SDM recorded a maximum change in velocity of -7.78 miles per hour. The crash pulse was much shorter in duration than Tests #1 and #2, the change in velocity was slightly greater than in Test #2, and thus the airbags deployed.

Test 3

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In all three tests, there was evidence on the roadway, as well as both vehicles, that would indicate to an investigator how the vehicles were positioned at impact and post-collision movements.

Even though it was not the goal of the tests, damage profiles and contact patterns were compared. When examined on its own, the evidence would have presented an accurate depiction of the collisions.

Test 1

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The impact in Test #3 was 37.10 miles per hour, and was planned at a higher speed to ensure airbag deployment.

The motorcycle was positioned and balanced in the same manner as Test #1, with the exception of the dummy’s left hand.

The Chevrolet was braking at impact.

It left light, but distinctive marks from all four tires. The impact did not cause its path to deviate. The bumper cover was deformed and retained the relative shape of the front wheel of the motorcycle.

specifically a value of -0.5g was used for the displacement of the motorcycle based on the observed scrapes and gouges generated by the post-impact motion. Similarly, a value of -0.5g was also assigned to the post-impact displacement of the Cavalier because full post-impact braking was not indicated by the ground evidence. The right front wheel was off the ground for about seven feet after impact.

Using this information the atimpact speed of the Cavalier is computed at 37.6 miles per hour. The speed changes as a result of the collision can be derived for the automobile to be approximately 7.6 miles per hour, and 34.4 miles per hour for the motorcycle. This data is consistent with the video motion data that allowed for the computation of a postimpact velocity of 34.7 miles per hour for the motorcycle.

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Test #3

Corrected IST Average fx during impact (g)

-1.10

-3.21

Corrected IST Peak fx during impact (g)

-5.85

-11.96

IST ∆v (mph)

-7.22

-8.31

Contribution of -0.72g to IST ∆v (mph)

-2.85

-1.39

Corrected IST ∆v (mph)

-4.37

-6.92

SDM ∆v (mph)

-6.36

-7.78

Contribution of -0.72g to SDM ∆v (mph)

-2.85

-1.39

Corrected SDM ∆v (mph)

-3.51

-6.39

Corrected motorcycle ∆v (mph), assuming 100% energy exchange

-19.80

-31.35

Table 4. Summary of contribution of full braking to overall change in velocity. Test 1 is excluded because the front axle lifted off the ground throughout the collision sequence.

Premiere. Videos, photographs, and an expanded version of this paper are available at the web site: (http://www.

Many individuals beckforensics.com) contributed to the success of this research project. Simon TerryLloyd of Rancho Del Oro Towing provided the vehicles. Special thanks to the County of San Diego for time and equipment used in this research. In addition to the authors, the field crew included Nischel Casteel, Sigifredo Miramontes, Eddie Hernandez, and J.J. Miramontes.

Video editing was completed by Sigifredo Miramontes using Adobe c

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cknowledgments:

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Underreporting in these tests was examined by contrasting the independent IST data against the SDM data. The SDM data works with a forward discriminating sensor and this impact configuration was purposefully narrow. Consistency was observed between the recorded accelerometer data for both devices.

That data, when viewed globally, with

Because of the small sample size and the limited types of motorcycles and vehicles, the project director has planned future tests involving a wider variety of motorcycles, vehicles, and SDMs. This project will contribute to a better understanding of EDR under-reporting by giving investigators the necessary tools to investigate and reconstruct collinear motorcycle-motor vehicle collisions.

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Based on data obtained by the SDM and IST in Tests #2 and #3, the Chevrolet SDM underreported the change in velocity by 0.53 to 0.86 miles per hour and by 6% to 12%. Given that the Chevrolet sustained less than 3.7° of rotation from impact to rest, the effect of the location of the SDM and IST on the recorded crash pulse would be negligible. Significant post-impact rotation requires an energy component that does not contribute to linear acceleration, which could then result in the SDM underreporting the actual change in velocity. Furthermore, given the lack of deformation to the Chevrolet’s floor pan, the actual location of the SDM would have only a negligible effect on the recorded crash pulse.

In collisions involving two vehicles with similar mass, the effect of braking may be negligible. However, in collisions involving vehicles or parties with disparate mass, the effect of braking in the larger vehicle on the overall change in velocity for the lighter vehicle could be considerable.

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high-speed films and speed trap information, indicates that the SDM underreporting was less than 12%.

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independent of the effect of braking through the collision sequence on each test (see calculated ε in Table 6).

The “corrected” values indicate the closing speed after accounting for the influence of braking. The significant contribution of pre-impact braking to the overall change in velocity is apparent in all three tests. The weight for the motorcycle includes the rider weight, as verified with high-speed films, the test dummy remained with the motorcycle through maximum engagement.

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Test 1

Test 2

Test 3

IST ∆v

17.11

40.49

46.61

-0.225g Correction to IST ∆v

11.95

n/a

44.31

-0.72g Correction to IST ∆v

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24.51

38.81

SDM ∆v

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35.67

43.64

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41.34

-0.72g Correction to SDM ∆v

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19.69

35.84

Actual closing speed

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27.21

37.10

Calculated ε (data source)

0.43 (IST)

0.31 (SDM)

0.18 (SDM)

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-0.225g Correction to SDM ∆v

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Figure 1. Photograph of SDM (right) and IST (left) accelerometers.

The right front passenger seat was removed for these tests. The two IST accelerometers were “piggy-backed” onto a wood platform, which was then bolted to the floorboard. (Left)

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Table 6. Summary of computed closing speed values (mph) from listed equation.(Table 6 – note: With the coefficient of restitution of zero assumed, the “closing velocity” equation significantly over-estimates the actual closing speed which was measured via speed trap data. The “calculated epsilon” when inputted into the equation returns the actual closing speed as determined from speed trap control data).

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Figure 2. Skid test data from IST accelerometer and Stalker radar. Note the latency associated with the Stalker radar around the 5-second mark.

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Figure 3. Crash test #1. Note the lifting of the Chevrolet’s front wheels.

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Figure 5. The Kawasaki and Chevrolet at final rest in crash test #1.

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Figure 4. Impact alignment in crash test #1.

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Figure 6. The Chevrolet after crash test #1.

Figure 7. The Kawasaki after crash test #1, in preparation for test #2. Note the minor fender damage and fairing scrapes.

Figure 8. Crash test #1 data from IST accelerometer from IST accelerometer and Stalker radar.

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Figure 9. Crash test #1 data and Stalker radar.

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Figure 10. Crash test #1 data from IST accelerometer and Stalker radar.

Figure 11. Crash test #1 data from IST accelerometer and Stalker radar.

Figure 13. Impact alignment in crash test #2.

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Figure 12. Crash test #1 data from IST accelerometer and Stalker radar.

Figure 14. Crash test #2.

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Figure 15. The Chevrolet after crash test #2.

Figure 17. The Kawasaki after crash test #2. The front forks sustained minor torsional damage. The wheels at the top of the photograph are not those of the test vehicle.

Figure 18. CDR file for crash test #2.

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Figure 16. The Chevrolet after crash test #2.

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Figure 19. CDR file for crash test #2: SDM recorded delta-v.

Figure 20. Crash test #2 data from IST accelerometer and Stalker radar.

Figure 22. Crash test #2 data from IST accelerometer, Stalker radar, and SDM.

Figure 23. Crash test #2 data from IST accelerometer, Stalker radar, and SDM.

Figure 24. Crash test #2 data from IST accelerometer and Stalker radar.

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Figure 21. Crash test #2 data from IST accelerometer and Stalker radar.

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Figure 25. Impact alignment in crash test #3. (Left) Figure 26. The Kawasaki after crash test #3. Note the damage to the front forks and front rim. (Right)

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Figure 27. The Kawasaki after crash test #3. Note the damage to the front forks and front rim. (Top) Figure 28. Crash test #3 at final rest. Note that the bumper cover is attached to the motorcycle. (Bottom)

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Figure 29. The Chevrolet after crash test #3. (Left) Figure 30. Crash test #3. Note that the front wheels of both vehicles are off the ground, and that the Kawasaki’s gas tank is separated from the frame. (Right)

Figure 31. CDR file for crash test #3.

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Figure 32. CDR file for crash test #3: SDM recorded delta-v. (Left) Figure 33. Crash test #3 data from IST accelerometer and Stalker radar. (Right)

Figure 34. Crash test #3 data from IST accelerometer and Stalker radar. (Left) Figure 35. Crash test #3 data from IST accelerometer, Stalker radar, and SDM. (Right)

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Figure 36. Crash test #3 data from IST accelerometer, Stalker radar, and SDM. (Left) Figure 37. Crash test #3 data from IST accelerometer. (Right)

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Case Study solution (c )

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Knowing what to look for and where to find it

his case study is based on a crash test conducted in Phoenix in July, 2005 for the Southwestern Association of Technical Accident Investigators (SATAI). The Lumina was parked off the road, beyond a curb up on a hard packed, dry (as one may imagine, it was, after all Phoenix in July!) dirt surface.

The Cavalier was driven in an arced path leading to the curb, struck the curb then moved over the dirt, uphill to the flat surface and struck the Lumina.

T

“time between non-deployment and deployment events (sec).” In this instance, it reads “1 (one).” This tells us that the non-deployment preceded the deployment by about 1 second.

Once again the issues raised for discussion here may or may not be the same from one instance to another but they are selected for discussion in this context and to give a more narrow focus to the case study at hand. The issues and answers associated with this case study are appropriate for this case alone and may not be appropriate or applicable to another crash scenario given varying crash facts. Alright, having said that...some answers for the issues posed follow:

Solution: Unlike question #1 above, answering this question requires we know something about the crash itself.

In this instance, we have a crash scene and photos of the crash scene that show the path of the Cavalier to a curb then beyond the curb to strike the Lumina. Looking at the data and distances involved, and knowing the non-deployment occurred before the deployment, we can deduce that the curb strike brought about the non-deployment then the collision with the Lumina caused the deployment. This deduction would be consistent with observations at the test and instrumentation used in the test as well and is an example of a situationally complete reconstruction.

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(1) There are two events recorded for the Cavalier, in what order did they occur?

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(2) What is the most probably reason for the first event recorded and displayed in the Cavalier’s download? What action or impact caused the first event recorded by the Cavalier?

Solution: Assume we know little about the event for the moment, the order of events is found described in the CDR report text itself. In this instance, the deployment record and the on-deployment record are both recorded for the same ignition cycle (8978). The key to this solution is to find the line in the deployment file that reads:

(3) There is an apparent speed loss for the Cavalier over the period approximately 1 second to 2 seconds before “AE” where the reported speed appears to be 31mph then drop to 14 mph. There is a brake switch “on” indication at approximately 2 seconds before “AE” then “off” Collision 97

at about 1 second before “AE.” With those observations in mind, what explanation can you give for the apparent speed loss over that second? One should explore possible explanations including:

airbag control module (the SDM) and took a photo of it beside sticker, the “Service Parts Identification” label.

Without using an internal GM source, we did what anyone else can do, research RPOs on the web. Using that approach, we found that the codes on this label can be interpreted as seen below:

In this crash test study, we removed the Collision 98

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RPO means “Regular Production Options.” These are codes GM uses when building it’s vehicles. Some are easily found in service manuals, shop manuals or scrapping guides but sometimes the manufacturers don’t tell us what they all mean..exactly. Some can be as simple as what paint color your vehicle came with or what compliance stickers were put on the car during production others are just used in the manufacturing process and don’t mean anything specific to end users. RPO codes can usually be found in your glove box or in the trunk and are 3 character codes. (See photo)

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(3a) that there was “pre-crash data resampling (also know as “data buffering”)” for the “-1” samples and that speed is therefore under reported, AK5: restraint system, inflatable, driver and pass AR9: seat, frt bkt, european style, pass a driver recl Solution: No, this isn’t the reason, there is no mention C49: defogger, rr window, electric of the potential for the data resampling condition found C60: hvac system, air conditioner frt man controls mentioned in the Data Limitations text so it is not the Dl5: decal, roadside service information explanation for that apparent anomaly in this case.

D35: mirror, outside rear view FE0: suspension system, frt & rr, active (3b) that the brake switch status is reported incorrectly FE9: certification, emission, federal (reversed) for certain Cavaliers including the 2001 year FX1: ratio, transaxle final drive 3.94 model and this case we’re dealing with a 2001 Cavalier, IPC: trim-interior design JM4: brake, system, pwr, frt disc, rr drum, cast iron, Solution: No, this isn’t the case here. Yes, there is the K62: generator 105 amp dual internal fan potential for a reversed brake switch sign indication in LN2: engine, gas, 4 cyl, 2.2l, mfi certain model Cavaliers and Sunfires; HOWEVER, this L0D: lordstown ohio production plant anomaly requires that the car be a 2.4litre engine (RPO MM5: 5 speed manual transmission LD9) AND manual transmission (RPO MM5). What M94: manual transaxle engine and transmission does this Cavalier have?

NF8: emission system, federal tlev NK5: steering wheel, standard One way to determine that would be, of course, to inspect PC1: wheel, 14 x 6, steel the car but what if, as a consultant hired after the fact QFB: tires p195/70r14 90s bw one has to make that determination or, at scene, you can’t SLM: stock order, processing code tell for sure because (as seen in the photos) this Cavalier UM7: radio, am/fm stereo, seek/scan, clock, etr (base on DOES have a manual transmission? What Other steps all models) US6: antenna, fixed, painted, radio can be taken. By the way, what’s an “RPO?”

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UX7: speaker system, 4, dual frt dr mtd U2E: cluster, inst, cool temp, trip odom VH9: envelope, owner info man VM3: label information consumer contains bpr imp standards V73: vehicle statement usa/canada 1AY: stock orders processing opt (dlr ordered car) 1SA: option package 01 1SZ: discount option package 16U: primary color. exterior, brite white 52C: neutral cloth interior 52I: trim, lt neutral (i) (92) 6CB: suspension option 7CB: suspension option 8DH: suspension option 9DH: suspension option

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In the RPOs, we see that this car DOES have a manual transmission with the RPO MM5. We see; however, that the engine is a 2.2 not 2.4 litre engine which is an RPO LN2. So, the reversed switch anomaly does NOT apply in this case. This car has delta-V graph and table for the deployment event. Afthe transmission but not the engine option required for ter that, in the “100ms” and then “110ms” samples, the this anomaly to be present. delta-V takes an “upturn”or appears to become relatively less severe. What explanation can be given for this appar(3c) there is actually braking pre-impact and that means ent “upturn?” the wheels on the Cavalier are locking and causing the speed to be under reported at the “-1” sample.

Solution: Reading the Data Limitations text for the Cavalier we see this car is subject to what’s called “Adjusted Solution: This could well be the case. A review of some Algorithm Velocity Change” for deployments. In short, of the video and action photos shows the car “jumping” this means for long duration events and those with off the curb then bouncing over the dirt to the impact with axis impulses, the airbag control module can under report the Lumina. We’d want to look more closely at the marks delta-V as a function of what might be best described as on the dirt for an objective indication of the status of a re-zeroing of the module’s accelerometer. These modthe tires: are they rolling or locked? In this case, the dirt ules are susceptible to under reporting delta-V not over shows to be smeared, not a print but a displacement of the reporting it and as a function of that we see the delta-V dirt leading to impact. It appears that the Cavalier wheels graph appearing to move in a “positive” direction toward were not rolling freely. As such, we can expect the signal the end of this event. from the Vehicle Speed Sensor (VSS) to send a lower than actual center of gravity speed to the powertrain control (5) One may assume for the sake of this study, that “redmodule (PCM) and, for that reason, we see the speed of line” on the Cavalier is about 6000RPM. In the Cavalier “14mph” rather than the actual speed at that point. This download report, for the entire time captured for “preobservation is checked and is consistent with instrumen- crash data,” one sees “0” (zero) for percent throttle; howtation from the test. The explanation then is pre-crash ever, the engine speed captured is as high as more than braking and vehicle dynamics as discussed further below 5000RPM. Even when the brake switch status is reported caused an under reported speed at the “-1” observation. as “on,” the engine RPM is as high as some 3500RPM. What explanation can be offered for this apparent contra(4) The delta-V for the Cavalier appears to be about - diction in the pre-crash data elements?

15.6mph at what is marked as the “90ms” sample on the Collision 99

warning lamp is “ON” at the time of the non-deployment (consistent with a previous deployment) and that the line that reads “A deployment was commanded prior to this event)” (“this event” meaning the non-deployment here) reads “YES.” (7) The data downloaded from the Lumina does not display any pre-crash data. Would this be an indication of a “power interruption?”

Solution: No, not all modules capture what’s known as “pre-crash data.” In this case, the module was simply not capable of capturing “pre-crash” data.

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Solution: Looking back to issue/question 3b in this case study, we see that the car has a manual transmission. The answer is, in this case, that the transmission was down shifted harshly. As a function of that, there was engine braking (further complicating the answer to issue 3c above), the engine RPM revved high and the car was actually slowed. How would you know this in a “real world” case? You may not. You may have to surmise that based on the investigative steps you would take. What cannot be done is try to “tie” throttle and RPM together and draw conclusions from that alone. One must always remember “pre-crash” data is captured asynchronously and each data element is a stand alone, separate observation (c )

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(5a) Identify investigative steps which might be taken to (8) The Lumina download shows a non-deployment evaluate and explain the apparent contradiction in the event. That non-deployment event shows a delta-V of -1.1mph over about 34ms. For the sake of this case study, pre-crash data seen in topic “5” above. one may assume that the actual, total delta-V for the LuSolution: The observations of witnesses hearing the en- mina is about -10.3mph. As it relates to this case study, gine revving may well guide the investigator to look at assume that this value may have been calculated as part of this as a possibility but determining what transmission a reconstruction. Explain the difference in the calculated the car has and looking closely at the pre-crash tire marks delta-V of -10.3mph and -1.1mph as reported in the Lumina data report. could help the investigator evaluate this possibility.

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(6) Relative to the data downloaded from the 2001 Lu- Solution: Now, it’s time for a more thorough analysis of mina, there are two events recorded for the Lumina, in the crash. We need to do a more thorough momentum analysis for impact and closing speeds, total delta-V and what order did they occur? then PDOF...but those are the clues. The more complete Solution: In this case, the ignition cycle count for the two answer in the next issue of COLLISION where the topic events points to the observation that the deployment oc- of this section turns to calculating closing speed! curred before the non-deployment. Further, in the nondeployment data section of the report, we see that the

Collision 100

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Collision: The International Compendium for Crash Research

ollision C The International Compendium for Crash Research

Volume 1 Issue 1

Accuracy of Speed Recorded by an SDM & the Effects of Brake & Yaw Events Analysis of the GM Sensing & Diagnostic Module in 360 Degree Linear Momentum Collisions: Real Case Analysis CDR Data Presentation & Validation in Legal Proceedings

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A Review of Various ACM Module Types & Data Recorded Implementing Policy for CDR Incorporating CDR Services in an Existing Forensic Practice Motorcycle Collinear Collisions Involving Motor Vehicles Equipped with EDRs

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