Volume 4, Issue 1

Crash site evidenCe

A 1968 Mustang GT, driven by Lt. Frank Bullitt, is chasing a 1968 Dodge Charger R/T, driven by a man known only as “The Killer,” down Taylor Street on Russian Hill in San Francisco.

Collision: The International Compendium for Crash Research

For a full reconstruction of this 46 second chase sequence, visit www.edccorp.com/bullitt

HVE directly answers the following questions using Newton’s laws of motion:

Questions

Answers

Speed on Taylor St.

30 – 37 mph (both vehicles)

Driver Inputs

Mustang: 2-3 lb brake pedal force, 200 deg left steer onto Filbert, then 25-65 %WOT Charger: 3-5 lb brake pedal force, 175 deg left steer onto Filbert, then 70-75 %WOT

Maximum Undercarriage Impact Force

Mustang: Fx= -1730 lb, Fy= -13 lb, Fz= -2120 lb Charger: Fx= -8610 lb, Fy= -120 lb, Fz= -11100 lb

Maximum Suspension Force

Mustang: 4330 lb @ L/F; 3270 lb @ R/R Charger: 4810 lb @ R/F; 3530 lb @ L/R

Hubcaps Lost

Mustang: N/A (American Racing Mags) Charger: Five

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4/8/09 1:26 PM

Volume 4, Issue 1 - SPRING 2009

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EDC COL Ad 4_9_09.indd 1

The International Compendium for Crash Research

Volume 4 Issue 1

Spring 2009

CDR Evidence: FAQs Forensic Photography

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Accuracy of Selected 2008

Chrysler ACM EDR’s During Braking

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of interest

4 Letter from Editor

Contents Spring 2009 Volume 4, Issue 1

6 Industry Partners 10 Calendar 12 Professional Societies 94 Book Reviews

18

98 Index of All Collision Articles 102 CDR Software Release v3.2

features

14 Photo Rectification Plays an Important Role for Determining Fault in a Two Vehicle Crash by Lee DeChant

66

18 ACM Reprogramming by Chuck Veppert 26 Signal Processing Applied to Vehicle Speed Measurement and Recording by Gary Johnson 32 Accuracy of Selected 2008 Chrysler ACM EDR’s During Braking by Richard Ruth & Tim Reust 40 Calculating Speed From Skidmarks by Peter Bergh 44 Ranges of Safety Provided by Safety Technologies Used For Reducing Motorcycle Crashes, Fatalities, Injuries and Loss by William Belisle

26

62 CDR Evidence Frequently Asked Questions

by William J. Melkonian 66 The Mathematics of Turns, Evasive Maneuvers, Lane Changes, and Passing

by Peter Bergh 32

74 Using Ford PCM Data to Evaluate Deceleration Rates, Brake Time and Impact Speeds by Tim Reust, Richard Ruth, James Morgan 80 Alcohol and Vehicle Collisions Correlation or Cause? by Peter H. Rast 88 Forensic Photography and Crash Reconstruction Part 2: Solutions to Common Problems by Robert Wyman www.collisionpublishing.com

Collision

3

from the editor It seems like only yesterday we were working on the first issue Collision and now we've entered our fourth year with this, Volume 4, Issue 1. In just a bit more than three years, Collision Magazine has distributed more than 20gig of crash data, photos, presentations, crash test documentation, research, and so much more it's difficult to really start to fully describe the impact (yes, pun intended!) this publishing adventure has become. Thinking back, it all began after the 1st Crash Data Retrieval User's Conference and was a result of efforts to ensure the presenters from that conference were able to publish their presentations and research to a wider audience but now, through the affiliation with the participating organizations - particularly NAPARS - it's become so much more and we look to the future for greater opportunities to be the print resource for reconstructionists worldwide.

I mentioned NAPARS, this issue marks a change in the leadership at NAPARS as Chuck Veppert takes the reigns as the President of NAPARS after John Meserve's retirement last fall. Chuck's long history with the organization and in the field promises to guide NAPARS into the future as the organization turns 25 this year. Their 25th Anniversary conference is planned for October in Ocean City, Maryland.

Where do we go from here? Collision Publishing, of course, is heavily involved in helping Bosch and the auto manufacturers with the many changes in the Crash data Retrieval system and looking toward future expansion of the system potentially beyond North America. We were involved in a set of first of their kind independent crash tests specifically designed to evaluate CDR related data for Chrysler vehicles and, as we look toward the ARC-CSI conference in Las Vegas in June, we're anticipating a continuation of that series of tests with another group of late - very late - Chrysler vehicles. (On the disk included with this issue of Collision is the presentation from the CDR User's Conference on some of the highlights of the Chrysler vehicle testing.)

Beyond that, having looked at where we are with Collision, we're seeing more and more interest expressed by those in the field wanting to be published in Collision and/or present at the ARC-CSI or CDR User's Conference. We take that as a promising step in the evolution of Collision and its broader application to the community. Look to future issues for articles on "best practices" authored by leaders in the field from within the auto industry and for innovative approaches to problem solving by those within the larger reconstruction community.

The political buzz word of late seems to be "change," and as that might be applied to Collision, our plan is less so much "change" and more along the lines of "value". We've been offered more original articles and papers than ever before and look to continue to provide the readership of Collision the best possible print and digital resource available.

Managing Editor

4 Collision

www.collisionpublishing.com

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

Conference CD Included with this issue of Collision is the 2009 CDR User's Conference CD. The CD includes all the Power Point presentations from the conference plus any additional handouts and data. In addition, the CD also contains any additional data, photographs or video that may accompany articles from this issue.

All rights reserved, © 2009 Collision Publishing LLC. The opinions and conclusions expressed in this publication and attached data disk and throughout the articles attributed to specific authors are the opinions and conclusions of the authors noted and not necessarily the editorial staff or anyone else for that matter. While some articles have been reviewed for content, the accuracy of reprinted models or equations cannot be fully guaranteed. It is the responsibility of the reader to apply critical thinking to an individual review of the content and make their own personal judgements as to its value to them, individually. At the end of the day, facts belong to everybody, any other opinions to us. The distinction is yours to draw...otherwise, the opinions expressed herein are not necessarily those of any employer, not necessarily ours and probably not necessary. Dissenting opinions, discussion or conclusions which may express an adverse position to those expressed herein by specifically cited authors can be addressed in writing by sending an email to the editor at editor@collisionpublishing.com or sending a “regular mail” letter to us at PO Box 3383, Kirkland, WA 98083-3383. By sending correspondence to either our email or snail mail addresses listed in this publication you are agreeing that: (1) we are by definition, “the intended recipient” (2) all information in the email is ours to do with as we see fit and make such financial profit, political mileage, or good joke as it lends itself to and, (3) this overrides any disclaimer or statement of confidentiality that may be included on your original message. The entire physical universe, including this publication and attached data disk, may one day collapse back into an infinitesimally small space. Should another universe subsequently re-emerge, the existence of this publication and data disk in that universe cannot be guaranteed.

Submit an Article If you would like to submit an article to be published in Collision please refer to the published Article Submission Requirements Guide located at: http://www. collisionpublishing.com/pdf/CollisionArticleSubmissionGuidelines.pdf. You may also email us your article for review or call us toll free 800-280-7940.

Email: editor@collisionpublishing.com

Scott Baker Sean Haight Tonya Baker Shawn Greene

Owner, Managing Editor Editor Advertising Manager Subscription Manager & Customer Relations

Advertiser Index Visual Statement

...........Inside Front Cover

Calc Zone Pro

......................................1

MapScenes

......................................2

iWitness

......................................8

Cad Zone

......................................9

Eos Systems Inc.

....................................25

Collision Publishing

....................................31

WeCare

....................................39

IST

....................................43

MapScenes

...............................57-60

Collision Safety Institute

....................................61

Northeastern University

....................................65

Vericom Computers

....................................73

WeCare

....................................97

VBOX USA

..................................101

CSV Pro 2009

..................................104

4N6XPRT Systems

............Inside Back Cover

EDC

......................Back Cover

Adverstising Rates & Information If you would like to advertise your product or service in Collision Magazine, please visit our web site for demographics, advertising rates, placement and sizes. www.collisionpublishing.com

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

www.collisionpublishing.com

Collision

5

From the Desk of the President It seems like just a short time ago we were sitting at large banquet tables in Atlantic City, NJ listening to President Frank Volpicella of NJAARS welcoming us all to the 2008 Annual Combined Conference. I sat there thinking about all the great crash training conferences I had attended since my first trip to the Lancaster, PA combined conference in October of 1995. Each year since, a different organization has given us the opportunity to gather together to learn from experts in our discipline and share our knowledge and friendship. By attending the annual conferences, I have had the privilege of meeting and talking with many of the leading experts in the field of crash reconstruction. The knowledge gained from the technical presentations and specialized training has benefited me countless times in my reconstruction career. Not to mention the many opportunities to witness and participate in live crash testing. (Learning Newton’s laws from a physics textbook is fine, but observing them in action is much more rewarding!)

Fast forward now to April and we are hard at work planning for the 2009 Conference to celebrate NAPARS 25th anniversary. Over October 5-9, 2009 we hope to host our best annual conference yet at the Grand Hotel on the Boardwalk of Ocean City, MD. The main topic will focus on Commercial Crash Reconstruction, with presentations on truck/bus ECM data accuracy, testing and downloads of the various manufacturers ECMs, solving heavy vehicle momentum problems, speed from sideswipe evidence, and interpreting post-crash MCSAP inspection data just to name a few. Crash test day will include instrumented crash testing with tractor-trailers in sideswipe and 90 degree crashes into cars, brake efficiency testing with out of adjustment air brakes, acceleration into a turn testing with heavy vehicles, and the opportunity for attendees to actually get behind the wheel and drive a tractor-trailer. Other test track presentations will be offered between crash tests to maximize training opportunities and minimize down time. An optional 8 hour Bendix air brake class will be offered early in the week that will cover basic air brake operation and function, ABS, and advanced air brake stability and control systems. ACTAR ceu’s will be offered for both the conference and the Bendix class. And as usual, there will be an ACTAR test offered prior to the conference.

Given the current economy, crash investigators and reconstructionists need to spend their training budgets wisely. With that idea in mind, NAPARS is working hard to bring you the best in crash conference training and testing at an affordable cost. See our web site at www.NAPARS.com for conference details.

If you have not been able to attend a combined conference in the past, I invite you to come and share in both the fun and the experience. For the many that have joined us before, we look forward to seeing you again in October!

Chuck Veppert President, NAPARS

6 Collision

www.collisionpublishing.com

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

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

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

ASPACI Inc.

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.

The California Association of Accident Reconstruction Specialists (CA2RS) was formed in April of 1998 with the objective of providing education, training, and resources in the field of accident reconstruction. We provide three quarterly training sessions a year for both Northern and Southern California; a total of six training sessions.

The quarterly training is free for members. In lieu of a 4th quarter training session, we have a two-and-a-half-day conference starting on Thursday and ending on Saturday at noon. There is a reduced fee for members to attend the conference which typically includes breakfasts and lunches as well as a vendor reception.

Membership in CAARS has other advantages, including discounts on AR Journal & AI Quarterly subscriptions, ACTAR exam fees, ARC Network memberships, Collision Magazine subscriptions, and discounts from various industry businesses and training providers. Most importantly the main benefit of CAARS is the net-

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

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

quite

Our 2009 training seminar is scheduled for the week of September 14, 2009 in Boise, Idaho and it will be sponsored by the Idaho State Police. More information can be found on our web site, www.iaars.org If you have any questions about IAARS or the application process, please feel free to contact me or any of the board members listed on our web page.

Dan Lofgren President, IAARS

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

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

working among the membership to enhance their expertise in the various facets of accident investigation and reconstruction.

This past year we celebrated our 10th anniversary and had a joint conference with SOAR who was celebrating their 25th Anniversary. Kevin Cassidy, Rudy Degger, Karl Pringle, and Al Sutcliffe were recognized as founding members of CAARS. Kevin Cassidy and Gordon Gray were recognized as past Chairpersons for the CAARS organization. Rudy Degger was presented with a plaque on behalf of ACTAR in recognition of his dedicated service and leadership as a member of the ACTAR Board of Directors from April 2001 through February 2008.

For more information about our organization, quarterly training, or conferences, please visit our web site at www.ca2rs.com. If you have any questions, please don’t hesitate to contact me via e-mail at chairperson@ca2rs.com.

Kent E. Boots CAARS, Chairperson

www.collisionpublishing.com

Collision 7

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

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

And, The Crash Zone also does animations!

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

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

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

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

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

Calendar Jun 2009 6/1/2009 - 6/4/2009 Las Vegas, NV 2009 ARC - CSI Crash Conference Collision Publishing LLC 6/1/2009 - 6/5/2009 Poughkeepsie, NY Forensic Mapping with Total Station DBS Forensic Mapping and Solutions 6/1/2009 - 6/6/2009 Tempe, AZ Inspection and Investigation of Com. Vehicle Crashes IPTM 6/11/2009 - 6/19/2009 Wisconsin Dells, WI 2009 MATAI Anual Conference MATAI 6/15/2009 - 6/26/2009 Concord, CA Advanced Accident Investigation WeCare Education

Jul 2009 7/6/2009 - 7/10/2009 Jacksonville, FL Energy Methods and Damage Analysis in Traffic Crash Reconstruction IPTM 7/6/2009 - 7/10/2009 Ames, IA Vehicle Dynamics Northwestern University 10 Collision

conferences, training, and meetings

7/13/2009 - 7/17/2009 Concord, CA Basic Accident Investigation WeCare Education 7/20/2009 - 7/24/2009 Albany, NY Crash Data Retrieval Certification Course Collision Safety Institute 7/20/2009 - 7/24/2009 Jacksonville, FL Interviewing Techniques for the Traffic Crash Investigator IPTM

8/10/2009 - 8/14/2009 Jacksonville, FL Inspection and Investigation of Commercial Vehicle Crashes IPTM 8/17/2009 - 8/21/2009 Jacksonville, FL Investigation of Motorcycle Crashes IPTM 8/21/2009 - 9/10/2009 Ames, IA Traffic Accident Reconstruction I Northwestern University

7/27/2009 - 7/31/2009 Concord, CA Intermediate Accident Investigation WeCare Education

8/31/2009 - 9/4/2009 South Burien, WA Crash Data Retrieval Certification Course Collision Safety Institute

Aug 2009

Sep 2009

8/3/2009 - 8/7/2009 Jacksonville, FL Applied Physics for the Traffic Crash Investigator IPTM

9/7/2009 - 9/8/2009 Valhalla, NY Traffic Accident Reconstruction I Northwestern University

8/3/2009 - 8/7/2009 Jacksonville, FL Crash Zone IPTM 8/3/2009 - 8/5/2009 Elk Grove, CA ACTAR Test Preparation Course FactualDiagrams.com

9/10/2009 - 9/11/2009 Vienna, Austria 4th International IIID Expert Forum: Traffic and Transport Information Systems International Institute for Information Design

www.collisionpublishing.com www.collisionpublishing.com

9/14/2009 - 9/18/2009 Concord, CA Basic Accident Investigation WeCare Education

10/26/2009 - 10/28/2009 Seattle, WA WATAI Fall Conference WATAI

9/21/2009 - 10/2/2009 Tempe, AZ Traffic Crash Reconstruction IPTM

10/26/2009 - 10/30/2009 Concord, CA Speed Determination from Crush Analysis WeCare Education

9/28/2009 - 10/2/2009 Jacksonville, FL Pedestrian Bicycle Crash Investigation IPTM

Nov 2009

9/28/2009 - 10/1/2009 Concord, CA Traffic Accident Reconstruction II WeCare Education

11/2/2009 - 11/6/2009 Concord, CA Basic Accident Investigation WeCare Education

9/28/2009 - 10/2/2009 Ames, IA Traffic Accident Reconstruction II Northwestern University

11/9/2009 - 11/13/2009 Tempe, AZ Human Factors in Traffic Crash Reconstruction IPTM

11/9/2009 - 11/13/2009 Jacksonville, FL Advanced Commercial Vehicle Crash Investigation IPTM 11/16/2009 - 11/17/2009 Spokane, WA Officer Involved Collision Prevention and Investigation Collision Investigation Solutions

DEC 2009 12/7/2009 - 12/18/2009 Concord, CA Advanced Accident Investigation WeCare Education

Oct 2009 10/5/2009 - 10/9/2009 Allentown, PA Crash Data Retrieval Certification Course Collision Safety Institute

If you would like to list an event, class, conference or seminar in a future issue of Collision, please send us an email with complete details of the event.

Email: editor@collisionpublishing.com Phone: 800-280-7940

10/5/2009 - 10/9/2009 Jacksonville, FL Advanced Crash Zone IPTM 10/12/2009 - 10/23/2009 Jacksonville, FL Traffic Crash Reconstruction IPTM 10/12/2009 - 10/16/2009 Tempe, AZ Pedestrian Bicycle Crash Investigation IPTM

www.collisionpublishing.com

Collision 11

Professional Societies 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.

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 325 paid members and are always looking for ways to strengthen and increase their membership. CA2RS holds its meetings at easily accessible local agencies, providing an environment for members to bring case studies, problems, or helpful solutions and tips to share with other professionals in the field.

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 - www.faro-inc.org - 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.

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.

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.

12 Collision

www.collisionpublishing.com

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.

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 850 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.

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.

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.

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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Collision 13

Photo Rectification Plays an Important Role for Determining Fault in a Two Vehicle Crash

Lee DeChant

DeChant Consulting Services – DCS Inc

ackground Photos of a crash scene can play an important role in measuring evidence through photogrammetric modeling and image-based rectification. In this instance, a single photo was taken by a police officer and used to reconstruct the position of vehicles involved in a head-on crash. The police photo was rectified, where the camera aim point (i.e., an oblique view) was transformed into a normal view (i.e., a plan view.) From the plan view, the photo can be accurately measured to help clarify what happened in the crash; either supporting, or conversely conflicting with what two drivers reported to police after the wreck.

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he Crash An SUV (Vehicle 1) was traveling Northbound on a two lane road. The driver of Vehicle 1 made an evasive action swerving to avoid hitting an animal crossing from the eastside of the roadway. At the same time, a driver of a truck (Vehicle 2) heading southbound had locked-up the brakes - also swerving across the centerline. Vehicle 1 and Vehicle 2 collided on the northbound lane side, which was evident by the road evidence and point-of impact.

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The driver of Vehicle 2 stated to the police that the driver of Vehicle 1 was “completely in the southbound lane." The police report was subsequently filed with the incident being the responsibility of the driver of Vehicle 1.

An experienced reconstruction practitioner reviewed one of the scanned police acquired scene photographs – analyzed months after the incident. The reconstruction practitioner determined that the police photograph revealed faint tire markings of the Vehicle 1 driver’s side tire (a yaw-mark) crossing over into the southbound lane. Visually, from the photograph, the tire mark of Vehicle 1 appeared to be less than one-foot into the opposing lane in relationship to the solid double yellow centerlines. If that were the case, the driver of Vehicle 2 could have just stayed “on course” (southbound), or swerved just slightly to their right, in the southbound lane and the two vehicles would not have contacted each other. roving Vehicle Position through Photo-Based Rectification The reconstructionist had contacted DeChant Consulting Services (DCS) for support in measuring the tire marking

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Figure 1 is the oblique police photo with Vehicle 1 “cross over” tire mark

of Vehicle 1. DCS reviewed the scanned image and felt there was enough natural feature entities present for control point marking (a minimum of 4 points) for planar rectification, which would yield the required tire measurement of Vehicle 1.

The scanned photograph displaying the faint tire marking of Vehicle 1 and Point Of Impact, was actually ‘marked-up’ by someone with a ball-point pen before it was scanned and the image quality of the scan was certainly not “high resolution”; but nevertheless, at the time of preliminary photogrammetric review, the scanned photo was still believed to be satisfactory for the image-rectification and measurement process.

The reconstructionist went back to the scene and imaged it with a metrically

Figure 2 are “control points” measured months after the crash in iWitness www.collisionpublishing.com

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Figure 3 are the same “control points” marked in XYRectify (for rectification)

Figure 4 The scaled and rectified photo with CAD overlay (plan view)

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Figure 5 oblique view looking north (SUV in Purple). The deer location is reference only

calibrated consumer grade digital camera. Specific natural features were key (i.e., present in the field-of-view during the scene photography/survey.)

These digital images would then be measured later with the iWitness™ photogrammetry software system (www.iwitnessphoto.com) by deriving “control points” for the image rectification using the XYRectify™ (XYR) software program. The same control points were marked in the scanned police photo (Figure 3) for the rectification process.

"XYRectify assures the scanned pixels are square – a requirement for accurate rectification measurement."

It should be noted that XYRectify assures the scanned pixels (i.e., rows & columns of pixels) are square – a requirement for accurate rectification measurement. As previously mentioned, the oblique

view of the photo is transformed into a “normal” or in this case, a “plan view” (Figure 4). With the image rectified, it can then be measured accurately in the XY axis (i.e., in the plan view.) In this accident, the position of the Vehicle 1 tire mark as it relates closet to the double yellow centerlines (see yellow arrow in Figure 1) was measured to be less than 4”. The physical orientation of the two vehicles upon crashing (i.e., point of contact) was determined through review of multiple crash scene photos taken by the police. ummary Image-based rectification requires the area rectified to be fairly flat for 2D measurement within the rectified plane.

From this plane, four (or more) spatially separated 2D (XY) or 3D (XYZ) coordinates (referred to as Control Points) are required to convert the oblique photo into a plan view for accurate measurement. The rectified image (once placed in a CAD diagramming program) also requires unit scaling in either the X or Y format of the image.

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iWitness and XYRectify are low-cost, accurate and easy to use image-based measuring tools for accident reconstruction and forensic measurement. The method for mapping from a single scanned photo, recorded from a police officer, has been summarized here.

In many applications XYRectify (single image rectification) can be used in the event the scene evidence was overlooked by the investigators (i.e., lack of being tape measured, or laser measured with a total station.)

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uman nature dictates that some percentage of us will look for alternatives to the “accepted practices” on how to make proper repairs. ACMs that deploy an airbag set a hard or locked code in memory that causes the SIR dash light to remain on, signifying that the ACM should be replaced. With few exceptions, vehicle manufacturers have instructed dealers and repair shops that the only proper (read proper) way to repair a deployed airbag system involves replacement of the used airbag control module with a new factory ACM. General Motors has issued a position statement on ACM replacement that states, in part:

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“Due to the critical nature of the design of Supplemental Inflatable Restraint Systems (SIR) also known as airbag systems) GM does not support the use of used, salvage, or imitation parts for repair. Only new, genuine GM warranted parts should be used in repair.... Never use airbag parts from another vehicle or source”. 1 GM’s position statement listed a number of reasons, but their basic message was that used or repaired ACM’s were not a safe substitute for a new, factory warranted part. An unofficial poll of several auto repair facilities showed that most other major auto manufacturers have expressed similar policies on ACM replacement. Following

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A C M REPROGRAMMING Chuck Veppert Valley Technical Services

that advice from the manufacturers means spending upwards of $200-$300 for a new ACM after a deployment event.

Over the past couple of years, a new industry has been born, supplying “ACM Reprogramming” services to auto repair shops and backyard mechanics. The various companies offer to reprogram deployed ACMs at a fraction of the cost of a new factory replacement. Reprogramming is generally performed by reflashing the EEPROM, but can also involve replacing internal resistors or fuses.

A quick search on the Internet will quickly result in numerous web sites offering ACM reset or reprogramming services. Some services claim to reload the “original” factory programming. “Factory fresh,” “better than new,” and “any vehicle” are just a few of the claims made in the advertising. One reprogramming service on eBay has over 1,000 "positive Feedback reports" from its customers, with 99% satisfaction. Of course, the average consumer can only judge the service based on a single element: does the red SIR warning light go out once I reinstall the ACM after reprogramming? If the light goes out, the consumer is satisfied. But are the reprogrammed ACMs really just like new? While far from comprehensive, past testing performed on some families of GM SDMs showed that they continue to command airbag deployments, even when they had previously done so in a past crash event. Could this reprogramming service simply be “turning off the SIR light,” or do they actually restore the ACM to its factory settings? What about the previous crash data in memory?

Although there are numerous vendors in the US, Canada, and abroad offering ACM reprogramming services, one was chosen to reprogram a series of used ACMs in order to study the consequences of resetting ACMs as they relate to a CDR analyst down-

loading crash data. Four modules with existing crash events were downloaded, photographed, and then submitted for reprogramming. Once they were returned, each was again downloaded and when possible, tested for their ability to record new crash events.

It was noted that the chosen vendor marked each reprogrammed ACM in black marker with an "OK!" written on the top surface of the metal case. odules Summary For the evaluation of "ACM reprogramming" services, four airbag control modules (3 GM and 1 Chrysler) modules were used for this experiment.

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ACM#1: SDM G2000 airbag control module • Obtained from a 2000 Chevy Impala • Contained a previous Deployment event at ignition cycle 3968, and a previous Non Deployment event at ignition cycle 3934 • A new non Deployment event was induced on the benchtop at Ignition Cycle 3985 (no ignition cycles at investigation on this ACM) After reprogramming service: • Event data was exactly the same.

• The same previous deployment and non-deployment events present before it was submitted.

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After further tests: • Subsequent attempts to set new benchtop events failed.

• Module rode along in a test crash at Atlantic City NJAARS Conference in '08 (14mph ∆V) into the rear of a parked car – still no new event.

• ACM appears incapable of recording new data So, in theory, if a crash investigator were to download this reprogrammed ACM after another “severe crash event,” there would be a valid Deployment event with pre-crash data @ approximately 40MPH at Ignition Cycle 3968. There would also be an DonDeployment event with INVALID pre-crash data some 17 ignition cycle later. Without ignition cycle’s at investigation, (not recorded on this module), how would this download be interpreted?

ACM#2: SDM GT2001 airbag control module • Obtained from a 2001 Buick LeSabre • Contained a previous minor ND event at ignition cycle 10366, ignition cycle 10377 at investigation.

• A new Deployment event was induced on the benchtop at 10378, now ignition cycle 10379 at investigation. See Figure 1 After reprogramming service: returned the module • Event data was exactly the same.

• The same previous Deployment and Non-Deployment events present before it was submitted.

• However… The current ignition cycle was reset to zero!

• Ignition cycles at investigation now reads 1, although the previous Deployment event is at 10,378.

• Frontal Deployment Level Counter now reads zero. See Figure 2 After further tests: • The “reprogrammed” module again was subjected to further attempts to set another Deployment event.

• The first attempt actually produced a new Non-Deployment event with a ∆V of 2MPH (old Non-Deployment - .21MPH) • The second (more robust) attempt to set a new Deployment event….produced a Deployment Level Event!

• The Frontal Deployment Level Event Counter jumped from 0 to 2. See Figure 3

"The reprogrammer was able to reset the Ignition Cycles and Frontal Event Counter back to zero."

Figure 1: Events when submitted for reprogramming for module 2

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The reprogrammer was able to reset the Ignition Cycle and Frontal Event Counter back to zero. But the ACM is incapable of overwriting the old locked Deployment event. Any new Deployment event would be written as a Deployment Level Event event in the Non-Deployment memory space. So again in theory, if a crash investigator were to download this reprogrammed ACM after a new “severe crash” event, they would see a Deployment event at 10,378 Ignition Cycle, a Deployment Level Event event at ignition cycle 3, and ignition cycle at investigation of 5. The Deployment Level Event data would be from the latest crash, but how would this download be interpreted by the analyst?

ACM#3: DCX3 – 0156 airbag control module • Obtained from a 2007 Jeep Grand Cherokee • Contained no events (capable of deploys/rollovers only – no NonDeployment events) • Two new Deployment events were induced on the benchtop, first a “First Prior Event”, then a “Most Recent Event”. (No further events could be induced after numerous attempts)

Figure 2: Download of events after reprogramming for module 2 www.collisionpublishing.com

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After reprogramming service: returned the module • Event data was exactly the same.

• The same two previous Deployment events were present, just as it was before it was submitted.

• The ACM case showed evidence that it was opened (the ACM is case secured by Torx screws).

Since the events have no identifying data (ignition cycle, acceleration/∆V data, etc) benchtop testing cannot evaluate whether it can set new events. However, since Chrysler modules appear to be limited to only writing to a memory location one time, it is doubtful it can. A download after a new crash event would likely yield the same two previous events, with no recording of the new event.

ACM#4 SDM Epsilon2005 airbag control module: • Obtained from a 2005 Chevy Cobalt • Contained a previous minor Non-Deployment event at ignition cycle 5905, currently ignition cycle 5929 at investigation.

• Several Non-Deployment events were induced using a crash sled (ACM connected to vehicle GM LAN for data) which produced events with a ∆V of 6, 10, 11, 12 MPH, all at ignition cycle 5929.

Figure 3: With new Deployment Level Event set after reprogramming for module 2

Figure 4: Events present when submitted for reprogramming for module 4

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Figure 5: First download after reprogramming for module 4

Figure 6: New deployment events set after reprogramming for module 4 www.collisionpublishing.com

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• Added a frontal sensor to sled, a Deployment event was set on the first attempt. See Figure 4 After reprogramming service: Returned the module: • Events recovered now shown as “NONE”.

• The previous D and ND events present before it was submitted were gone!

• The previous event data appeared to be erased.

• The ACM's case showed evidence that it was opened (ACM case secured by Torx screws).

Further tests: • Further crash tests were performed to set new Deployment and Non-Deployment events.

• The first test set a Deployment event.

• The second test set a Deployment #2.

• Subsequent download shows Ignition Cycle at events is now 0.

• This ACM appears to have been completely reset. See Figures 5 & 6

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onclusion: Reprogrammed ACMs will likely be a concern for CDR Analysts who will undoubtedly encounter them in the future. Although the testing was confined to only one reprogramming service, the testing showed less than promising results.

One, possibly two, of the ACMs were incapable of recording new crash events after reprogramming. Three of the four ACMs would provide inconsistent or confusing crash data if they were downloaded after a new crash event. Only one appeared to have been restored to its previous condition as promised.

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eferences: 1)# 08-09-41-003 General Motors Position Statement on Installation of Used, Salvaged, or Imitation Airbag System Components Feb, 25, 2008

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Collision 25

Signal Processing Applied to Vehicle Speed Measurement and Recording Gary Johnson

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bstract Several important accident reconstruction related parameters are monitored by a heavy truck’s electronic control module (ECM). This paper will discuss how the Vehicle Speed Sensor (VSS) works, how it communicates with the Electronic Control Module (ECM), and how the ECM converts the analog signal to a digital value that can be stored in binary format. “Smart” sensors will be briefly discussed. Alternate methods of vehicle speed sensing will also be presented.

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hat is “Signal Processing?”

Signal processing is the analysis, interpretation, and manipulation of a stream of information from a remote source. The output of a typical VSS is an analog signal. Thus the initial VSS processing is analog signal processing as compared to digital signal processing. Webster’s dictionary defines analog as: “of, relating to, or being a mechanism in which data is represented by continuously variable physical quantities.”

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ow does a speedometer work?

The first speedometer was the Eddy Current Speedometer. Patented in 1902 by Otto Schulze1, it uses a rotating flexible cable driven by gearing linked to the output shaft of the vehicle’s transmission. A small permanent magnet attached to the rotating cable interacts with a small metal cup attached to the shaft of the pointer on the speedometer. As the magnet rotates near the cup, the changing magnetic field produces eddy currents in the cup, which themselves produce a secondary magnetic field. The effect is that the magnet “drags” the cup, and moves the speedometer pointer in the direction of its rotation with no mechanical connection between the two parts. The torque on the cup increases with the speed of rotation of the magnet. A return spring is calibrated such that a given rotational speed of the cable corresponds to a specific speed indicated on the speedometer. This calibration must take into account several factors, including ratios

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of the output shaft gears that drive the flexible cable, the rear axle ratio, and the diameter of the driven tires. The main disadvantages of the eddy current speedometer are breakage, inaccuracy due to wear, and the need of a strong electromagnet for recalibration.

Today, the most common type of speedometer is the electronic speedometer. It receives data from a VSS, instead of a drive cable.

The VSS is mounted on the rear of the transmission near the transmission output shaft and consists of a toothed metal disk and a stationary detector that covers a magnetic coil. As the teeth move past the coil, they “interrupt” the magnetic field, creating a series of pulses that are sent to the ECM via twisted pair wires. The reason for the twisted pair wiring is to cancel electromagnetic interference in the analog signal from external sources. The VSS is a counting, not a measuring sensor. Speed is determined by counting pulses over a set period of time. The default sampling interval for a Cat-

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erpillar ECM is 30 milliseconds. The faster that the output shaft is turning, the higher of a count that the VSS sees, and the higher its output signal. Inside the ECM a digital clock is used to measure time. The ECM is programmed to continually compare the count, or signal, received from the VSS against its internal clock to determine actual vehicle speed. Theoretically, the VSS should send a signal whenever the vehicle is moving. At very low speeds, however, vehicle movement is insufficient to generate a high VSS output signal and the signal may be very weak or erratic when received by the ECM. In a Caterpillar ECM for example speeds below 1.5 miles per hour are ignored.

The speed of the vehicle is calculated using a programmable value for pulses per mile in the vehicle speed calibration settings.

PPM = M * Ra * N 31200 = 502 *3.90 * 16 Where M = tire revolutions per mile, Ra = Rear axle ratio, and N = Number of teeth on chopper wheel2

The calculated speed is then converted to a binary number and stored as a binary number because digital circuits are more stable than analog circuits. Digital circuits are very repeatable while analog circuits change operating characteristics with temperature and age. Identical analog circuits can behave differently due to differences in component manufacturing tolerances. Digital circuits on the other hand sum numbers identically. Another advantage of digital circuits is that they are programmable by simply changing the calibration value through software. In the case of a Caterpillar ECM, to changing a parameter such as pulses per mile can be accomplished with a computer program such as CatET. To reprogram an analog circuit would require changing capacitors and resistors. (Analog circuit can be calibrated with resistor dials, not software but hardware) In a mechanical system, the gearing on the speedometer cable would need to be changed, or the magnetization of the cup would have to be changed with an electromagnet.

Once the speed for the interval is calculated, it needs to be stored.

This is done by a process known as “sample and hold.” The sampled value is held until the next value is sampled. This results in a stair-

Staircase Graph www.collisionpublishing.com

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case waveform. This set of staircase values results in “quantization error.” Quantization error is the difference in the actual area under the interval curve, and the area of the rectangles. The quantization effect is usually very small. In a 10 bit analog to digital converter, an error equal to the entire amount of the last bit would be 2 to the 10 power, or 1/1024 or <0.1% 3.

After the sample has been quantized, the data contained in this example can be described using 2 bits or binary digits. The binary numeral system is a “Base 2” number system. This means that in a 2 bit system, there are 22 (4) levels. In an 8 bit system, there would be 28 (256) levels. Going back to the 2 bit example, each of the 4 sample levels can be described in ascending order as: 00, 01, 10, and 11. The more bits in the Analog to Digital Converter (ADC), the larger the number that can be stored. In general, digital signal processing systems use ADCs of 10 or 12 bits, meaning that the input signal would be measured against 210 (1024) or 212 (4096) levels.

The default maximum vehicle speed limit on a Caterpillar ECM is 127 miles per hour. With a resolution (also known as “Scaling per bit”) of 0.5 miles per hour, an 8 bit ADC would be a very good fit.

0 miles per hour to 127 miles per hour is 255 data points or one point below 28 (256). hat does the future hold?

Expect to see more widespread use of “Smart” sensors.

These are analog sensors coupled with microprocessors and Electronically Erasable Programmable Read Only Memory (EEPROM). The analog to digital conversion takes place inside the sensor and the binary values are broadcast to the ECM on a communication bus. For example, a traditional oil pressure sensor outputs a varying voltage depending on the pressure applied to the sensor. This voltage is not usually linear; it depends on the temperature of the sensor, and is a low-level voltage that requires amplification. In a smart sensor, the microprocessor reads the voltage, calibrates it using temperature-compensation curves and digitally outputs the pressure onto the communications bus. This saves processing power in the ECM, which otherwise would have to do these calculations. Among the parameters stored in the EEPROM are Manufacturer Identification, Model Number, Version Letter, Version Number, and Serial Number. These stored parameters are known as Transducer Electronic Data Sheets (TEDS4).

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Expect to see a decline in the use of dedicated VSS. Speed measurement capability via the Transmission Control Module or ABS module is already built into most new ECMs. Modern vehicles with automatic transmissions have transmission control modules that are already measuring the speed of the output shaft. ABS sensors on each wheel are able to measure the wheel speed of those

wheels. See below for a print from a Caterpillar ECM that shows this capability to measure vehicle speed from these modules. The “R/Mile” would be speed measured from the revolutions per mile of the transmission output shaft. The “Ratio” is the actual tire revolutions per mile versus the ABS assumed revolutions per mile. Both of the modules communicate with the ECM via the J1939 protocol communication data bus. ummary: The history and function of electronic vehicle speed sensors had been discussed. This is the simplest form of signal processing: the counting of an input signal where the actual voltage is not necessarily of concern. The sampling of a continuously varying signal where the amplitudes are important such as voice recording or image processing is a much more complicated task involving Fourier transforms and theorems dictating the minimum sampling frequency. With the imminent proliferation of module to module communication, pertinent communication protocols should be presented in future publications.

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otes: 1 http://w1.siemens.com/press/en/pp_cc/2005/04_ apr/sosep200501_10_(special200504)_1264810.htm, retrieved January 18, 2009.

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2 This is from an example on Page 18, Programming Cat Electronic Truck Engines. The actual product of the numbers is 31324, a difference of about 0.4%.

3 For more on quantization error, see Least Significant Bit (LSB).

4 See IEEE 1415.4 for more information. eferences: Caterpillar Electrical and Electronic Installation Manual, Caterpillar Publication LEBT3886-02

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Programming Cat Electronic Truck Engines, May 2005, Caterpillar Publication LEXT0023-01 SAE J1939 Recommended Practice for a Serial Control and Communications Vehicle Network SAE J1930 Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, and Acronyms –Equivalent to ISO/TR 15031-2 Marven, Craig, and Gillian Ewers, A Simple Approach to Digital Signal Processing. New York, Wiley 1996

Caterpillar ECM Transmission and ABS Vehicle Speed Calibration 30 Collision

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Dedicated to providing timely and current crash research and information.

This is the first publication of its kind, featuring conference proceedings, articles of interest, peer-reviewed papers, crash test data, industry news and research. Each issue includes either a CD or DVD with conference proceedings in PDF along with all supporting data including crash test videos and digital photographs.

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Accuracy of Selected 2008 Chrysler ACM EDR’s During Braking

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Richard R. Ruth, P.E. Ruth Consulting LLC Timothy J. Reust Accident Science, Inc.

ntroduction EDR’s are most accurate during steady state vehicle operation prior to any braking before impact.

Determining speed at impact from an EDR when braking is taking place has been limited partly by the potential over-reporting due to the time lag between the last data point recorded and the actual crash. Many of the newly released Chrysler EDR’s record precrash speed data at 0.1 second intervals, which is more frequent than earlier EDR’s from other manufacturers. This allows a much more precise determination of speed at impact. Like Ford and GM vehicle speed recorders, Chrysler vehicles record vehicle speed from a sensor on the transmission output shaft that rotates proportional to wheel speed. Braking slows the wheels and causes the vehicle speed to be under-reported. This article quantifies the degree of under-reporting during maximum pedal force application for the 2008 Jeep Commander and 2008 Dodge Dakota models. While the brake under-reporting and the time lag to impact resulting in over-report-

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ing tend to partially offset each other, the best speed at impact accuracy can be obtained by quantifying both effects. est Procedure The 2008 Jeep Commander and Dodge Dakota were tested because they have similar airbag control modules newly designed for the 2008 Model Year with 5 seconds of pre-crash speed, brake, and accel pedal data at 0.1 second intervals recorded in deployment events. The test vehicle was accelerated to the test start target speeds of 35, 50, or 70 mph. Speed was stabilized for several seconds and then the driver performed a panic stop, moving the right foot from the accelerator pedal to the brake pedal as quickly as possible and applying as much brake pedal force as possible. About two and half seconds in to the braking a deployment event was artificially created in the module to trigger event recording. The test procedure is shown graphically in Figure 1.

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with rollover activated side curtains, so Deployment Events could be created in the 2008 Commander ACM by having the passenger simply hold the module level during normal operation and then roll the ACM by 90 degrees to set a deployment event. For the Dodge Dakota frontal deployment events were created by using a spring loaded drawer slide fixture to accelerate the module forward, and then simulate a crash by having the drawer slide strike the end of fixture decelerating the module rapidly. The setup is shown below in Figure 2.

The vehicle was also instrumented with a VBOX III using differential GPS technology recording at 100Hz. The manufacturer’s stated accuracy of the VBOX is to the nearest 0.1 km/hr when averaged over 4 samples.

Figure 1

In preparation for testing the authors built a jumper wiring harness to go between the vehicle end of the ACM harness and the test ACM connecting only power, ground, and communications (to prevent airbags from deploying during simulated deployment events). The vehicle ACM was unplugged, replaced by the jumper harness, and connected to the test ACM which was held in the passenger’s lap on a fixture. The 2008 Commander was equipped

The VBOX also served as a data acquisition system. An auxiliary brake switch was taped on the brake pedal to independently monitor brake pedal initial application. The accelerator pedal position sensor was also tapped and fed to the VBOX. An accelerometer was attached to the ACM module to externally monitor G’s applied to the module. After each test run the VBOX file was saved and the ACM was read out after each event using Bosch CDR. Data was synchronized after the testing by lining up the VBOX inputs wit h the ACM inputs.

Figure 2

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est Results For the 2008 Jeep Commander six runs were conducted at a target starting speed of 35 mph. The vehicle had to be actively controlled with the accelerator pedal in order to get an accelerator pedal reading to register (versus speed control where 0 pedal % is reported), so there is some variation in the actual starting speed. The EDR speed is recorded internally in wholenumber kilometers per hour and then the Bosch CDR program also converts it to miles per hour and rounds it to the nearest whole number. This analysis was conducted in km/h to achieve the best resolution possible, and then results were converted to miles per hour for this publication. The authors learned that the Chrysler system truncates any fractional values to the next lowest whole integer. Because of the truncation, the data would be expected to under-report by 0.5 km/h or 0.3 mph.

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While this article is primarily about accuracy in braking, reviewing the steady state accuracy in Figure 3 is helpful to put the braking accuracy in perspective.

Figure 4

Figure 5 shows the same runs but displays the difference between the ACM and the VBOX in mph versus the VBOX speed. In addition to the six runs an average of the six runs has been calculated and displayed as a bolder line. The difference ranged from 3 to 12 mph during initial engagement.

Figure 3

Under steady state conditions at 35 mph, the average speed Difference was -0.24 mph (the negative sign indicating the EDR was under-reporting the VBOX speed data). At 70 mph, the average speed was under-reported by -0.13 mph. Data scatter was within approximately 0.6 mph of the mean. +/- 3 Sigma limits were calculated as if the data had a normal distribution. Because of the data truncation, the distribution has some of the characteristics of a uniform distribution and if a custom distribution were to be calculated the 98% confidence intervals would be even closer to the mean. More details of the steady state testing are published in SAE 2009-01-0884.

Figure 4 shows the six Commander runs starting near 35 mph and plots EDR speed versus VBOX speed. As expected the EDR consistently under-reports the VBOX speed. There is a larger Difference at initial braking engagement which becomes less once the anti-lock braking system begins to modulate the brakes.

Figure 5

Notice the oscillatory pattern in the Difference data. This was subsequently determined to be caused by the vehicle body pitching forward on its body mounts during braking relative to the frame, reaching the maximum forward travel, and then rebounding back on the chassis mounts repeating the oscillatory pattern until the motion was damped out. The pattern was more difficult to see in this graph because the data is plotted versus VBOX speed. When plotted versus brake engagement time (Figure 6) it is more pronounced.

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Figure 8

Figure 6

The initial peak occurs 0.3-0.4 seconds after initial brake application. If instrumentation could be devised to measure the chassis velocity, the peaks and valleys would be expected to be more damped.

Lastly at 35 mph, Figure 7 depicts the EDR/VBOX difference in percentage terms. The initial engagement peak averaged 25% with the highest individual value at 41%. Once the ABS system began to modulate, the Differences ranged from 2% TO 11%. As expected, as braking slowed the speed to near zero, percentage Difference becomes meaningless and even small Differences are reported as large percentages. The reason the data was looked at in percentage terms was to see if the ABS system was controlling to specified percentage of slip during hard braking.

Six runs were also made at 70 mph, and the EDR again consistently under-reports the VBOX. The initial engagement peak difference is substantially less than at 35 mph, ranging from 3.8 to 5.5 mph (versus 3 to 12). Also note the average difference decreases with speed. The composite of 70 mph and 35 mph Commander data is shown in Figure 8. The best fit line is Difference = -1.19 + .030 (Speed in MPH), and the approximate data variation is +/- 3 mph, with the exception that the 35 mph initial engagement peaks are outside the +/- 3mph band.

For the 2008 Dodge Dakota, six runs each were completed at 35, 50, and 70 mph starting speeds.

For reference, under steady state conditions, the Dakota ACM EDR read approximately 2% below the reference VBOX recorder.

Assuming a normal distribution resulted in +/- 3 sigma limits of approximately +/- 0.6 mph. The data scatter was relatively small and partially attributable to the EDR speed data truncation. The data is shown in Figure 9.

Figure 7 Figure 9

The Dakota showed considerably less brake engagement underreporting than the Commander did. One possible reason is that after the first few Dakota test runs at 35 mph, tire noise and smoke gave the false impression that the wheels were locking, and the authors reduced the deceleration rate to reduce the risk of excessive 36 Collision

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tire damage. After a review of the data, the wheels were not locking and the ABS system was functioning normally. Figure 10 shows the composite of 35, 50 and 70 mph initial start speed data for the Dakota, plotting the ACM to VBOX difference in MPH versus VBOX speed. The best fit line was:

Removing the initial engagement points from the Dakota results in a similar clear trend as shown in Figure 12.

The best fit line is: Difference = -0.48 - 0.046* (Speed in MPH)

Difference =-0.63-.039*(Speed in MPH).

Most data fell within +/- 3mph, with the exception of some of the initial engagement points.

Figure 12

Figure 10

More individual graphs of the test series are available upon request.

The authors are trying to help accident reconstructionists to better estimate speeds at impact during braking, and are trying to come up with simplified methods to do so. The authors considered that two different adjustment methods may be required for during initial engagement versus ABS modulation begins.

If the initial engagement data is excluded as shown in Figure 11, a relatively linear trend becomes apparent with best fit line Difference = 0.55 + .048 (Speed in MPH) This can be used to calculate the EDR to VOBX average difference.

Note the similarity between the Commander and Dakota best fit lines – in simplistic terms, about one half mph plus approximately 5% of the speed. This formula can be used to calculate an average under-reporting due to braking, and when accompanied with the data variance of +/-3mph can be used to estimate a reasonable range of under-reporting during braking.

During the initial engagement, the brake “grabbing” effect may be too dominant to permit ACM EDR data points during braking to be adjusted. The authors believed one possible way to calculate speed during this initial engagement is to start with the last data point reported before braking, and then subtract a calculated speed loss from the time of effective braking multiplied by the slope of the speed vs. time trace. This is a simple concept but is complicated slightly by the fact full braking does not begin instantaneously when the pedal is first touched. There is an initial delay before any braking occurs, then a ramp up of brake effectiveness, then full braking. The Jeep Commander braking engagement as a percent of full braking was plotted based on VBOX measured deceleration rates as shown in Figure 13.

Figure 11

Figure 13 www.collisionpublishing.com

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In this vehicle, it appears to take approximately 0.3 seconds from when the brake light first reports on to develop full braking. Due to the 0.1 second reporting interval, it is possible that the brake was actually touched up to 0.099 seconds earlier, and on average will be touched 0.05 seconds before the EDR reports it as on. This inherent delay in reporting is close to the delay in the beginning of braking effectiveness, so for a simple approximation it may be possible to begin calculating the braking from the first reported brake on point.

During the next 3 tenths of a second, the actual effective braking was 17% after 0.1 seconds and 58% after 0.2 seconds. By observation of Figure 13, the area under this curve is not significantly different than one generated by an approximation using a straight line increase from 0% braking at 0 sec to 100% braking at 0.3 sec. The drag factor can be obtained by exemplar vehicle tests, or if there is sufficient data during braking from the EDR. For this example the ABS drag factor is 0.847. If the first data point before braking is labeled as B-1, and the first point of braking is labeled B0, the following formulas could be used: B-1 = B-1 EDR SPEED = 34.2 MPH B0 = B-1 EDR SPEED = 34.2 MPH B1 = B0 EDR SPEED –0.33*(0.847)*0.1 sec*32.2 ft/ sec2*(60mph/88ft/sec) = 33.6 MPH B2 = B1 EDR SPEED -0.67*(0.847)*0.1 sec*32.2 ft/ sec2*(60mph/88ft/sec) = 32.3 MPH B3 = B2 EDR SPEED -1*(0.847)*0.1 sec*32.2 ft/sec2*(60mph/88ft/ sec) = 30.5 MPH Applying the formula to the entire data set from run C3 yields:

Which can be shown graphically as:

Figure 15

Looking at the difference versus the VBOX between the brake engagement speed loss model, and comparing it to the difference between the EDR and the VBOX, the brake time speed loss model increases the accuracy, especially during the initial brake engagement phase. For this particular data set, it even makes a good prediction after the initial engagement phase, although you would expect that the longer the brake time is, the more any potential difference would increase as any difference between the actual drag factor and the assumed drag factor would begin to accumulate.

When using the brake engagement speed loss model, it is important to keep in mind that this had been developed and tested based primarily on maximum pedal force application data sets. If the pedal force is less than maximum, and there is not enough time since brake engagement to get a good slope line, assuming a maximum brake slope line could result in calculating lower than actual speeds.

Figure 16 Figure 14

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Generally speaking, the authors experience is that the brake engagement speed loss model works well when there is one second or www.collisionpublishing.com

less of braking prior to impact in the EDR. For longer brake times, the under reporting formula may be more appropriate. Of course, the brake time speed loss model can also be projected beyond one second and compared to the under reporting formula, and the analyst could use their judgment as to which applied to the situation better. On Ford PCM EDR’s, the authors have used a variation of the speed loss model alone with success. Figures 17 show the suggestion of where to use the different models.

we would calculate the last EDR data point would correspond to a speed of 28.6 mph. The 95% confidence interval is approximately +/-3mph.

The maximum possible speed loss between last data point recorded and impact is calculated using the drag factor as 1.9 mph.

The range is 0 to 1.9 mph.

MAX Speed at Impact = 28.6 – 0 + 3 = 31.6 mph MIN Speed at Impact = 28.6 -1.9 – 3 = 23.7 mph.

For the same data set, if the last point in the EDR before impact was after 1.2 seconds of braking, we would use the formula model.

The EDR data point at 1.2 seconds of braking is 12.4 mph. The difference EDR from VBOX would be Y=-0.55-0.048(12.4) = -1.1 mph.

The estimated speed should be 12.4+1.1=13.5 mph.

MAX speed at impact = 13.5 -0 + 3 = 16.5 mph.

MIN speed at impact = 13.5-1.9 -3 = 8.6 mph.

Figure 17

Now that we have these models to assist us, let us apply them to calculating a speed at impact. For discussion purposes, let us say that the last EDR data point recorded was 0.4 seconds after brake engagement, at 23.0 mph. Using the brake time speed loss model

onclusion: Analysts are now equipped with a method to quantify EDR under-reporting during braking and to better estimate the range of possible speeds at impact from Chrysler EDR data.

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n r u t "Myt the a el" whe

I

ntroduction For calculations for a speed from a set of locked wheel skid marks of unequal length, normally we see one of three approaches applied: 1. Use the length of the longest skid mark in the standard skid formula as the "skid length" 2. Use the average length of the skid marks in the "standard skid formula" 3. Split the calculation into several steps, where each step of the calculation different braking efficiencies but equal length skid marks, using the standard skid formula in each step, and calculate a speed loss from each step. Finally, combine the speed losses from all speeds into one speed loss for the skid length

The assumptions underlying each of these approaches are: 1. The vehicle had full all-wheel braking all the way but the skid marks do not reflect that 2. The vehicle had full all-wheel braking for some distance but the length of the skid marks had some random variation. It assumes that the average length of the skid marks reflect the true skidding distance 3. What you see is what you had: the skid marks accurately reflect the braking on the individual wheels 40 Collision

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Calculating Speed Peter Bergh

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All three approaches give similar results when the lengths of the skid marks are close to each other and they of course give the exact same results when all skid marks are of the same length. When the lengths of the skid marks vary widely, the assumptions underlying the first two approaches normally are invalid and, as a result, these approaches give incorrect underreported results.

The purpose of this brief note is to suggest a simple formula to use when the lengths of the skid marks vary widely.

T

he mathematics of a skidding particle For simplicity, we assume that all skids are on a horizontal surface. The results can easily be generalized to work for skids on slopes.

We use vb for the speed of the particle before the skid, va for the speed of the particle after the skid, m for the mass of the particle, g for the acceleration of gravity, f for the coefficient of friction of the surface on which the particle is skidding, and d for the distance the particle skidded. Since energy is conserved in a closed system, we get:

Dividing the equation by and multiplying the equation by 2, we get:

Let us now assume that we have two skids immediately following each other. Let the speed between the two skids be vm and we’ll put an index of 1 on the first skid and 2 on the second skid. Applying our previous equation twice, we get:

the intermediate algebraic manipulations will be different. We use the same notation as above, but we need to introduce a few more variables. We denote the skid-mark lengths by d1, d2, d3, and d4.

We assign the indices such that d1 > d2 > d3 > d4. We number the wheels such that wheel 1 left a skid mark of length d1, wheel 2 left a skid mark of length d2, wheel 3 left a skid mark of length d3, and wheel 4 left a skid mark of length d4. Furthermore, we denote the weight on wheel 1 by mge1, the weight on wheel 2 by mge2, the weight on wheel 3 by mge3, and the weight on wheel 4 by mge4 (of course, e1+ e2 + e3 + e4 =1).

We split the skid into four pieces: 1. All four wheels left skid marks. The skid mark length for this piece is d4 and the braking efficiency is e1+ e2 + e3 + e4 , or 1 2. Three wheels left skid marks. The skid-mark length for this piece is d3 - d4 and the braking efficiency is e1+ e2 + e3 3. Two wheels left skid marks. The skid-mark length for this piece is d2 - d3 and the braking efficiency is e1+ e2 4. One wheel left skid marks. The skid-mark length for this piece is d1 - d2 and the braking efficiency is e1.

Adding the “energies” from these four pieces, we get:

When we simplify the expression, we get:

If we introduce the customary notation for sums, we get:

Adding the last two equations, we get:

(If we set va to zero, this becomes the standard formula to calculate a speed from a skid.) From this formula, we note that we’re not really combining speed losses, we’re adding quantities proportional to energies.

U

nequal skid lengths We have a set of skid marks whose lengths vary significantly.

We assume that this set of skid marks are on one level surface. To simplify the algebra, we assume that the skidding vehicle has four wheels. Expressing the results as sums, we get the same results for vehicles with a different number of wheels, but 42 Collision

(This formula also generalizes to more or fewer wheels.) Intuitively, this formula makes sense: we may consider the skidding car as four unicycles connected by massless, rigid rods. The unicycle riders begin braking at different times, producing the skid marks.

Let us now briefly look at the formula we use when we average the lengths of the skid marks. It is:

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We see that the averaging formula will yield correct results for arbitrary skid-mark lengths if and only if e1= e2 = e3 = e4 =1/4, i.e., if the weight of the car is evenly distributed across the four wheels. In practice, this situation is rare.

N

umerical example Let us assume that e1 = 0.18, e2 = 0.22, e3 = 0.29, and e4 = 0.31. We further assume that d1 = 160, d2 = 120, d3 = 80, and d4 = .40.

We assume that we want the speeds in MPH and that the given skid-mark lengths are in feet. We also assume that the coefficient of friction is 0.75. Finally, we assume that the car skidded to a stop. Under these conditions, our formula above becomes: We want to compare the results of the correct formula with the result of averaging the skid-mark lengths. The average skid mark length is 100 feet and the calculated speed from that average is 47.43 MPH.

When we plug in the numbers in our formula, we get 45.20 MPH. If we change the numbers around so that e1 = 0.31, e2 = 0.29, e3 = 0.22, and e4 = 0.18 we get the same value when averaging the skid-mark lengths, but our formula gives 49.57 MPH. We see that averaging the skid-mark lengths gives a value that is close, but "no cigar."

T

he bottom line...

If you average the skid-mark lengths when they vary significantly, you will get the wrong results. With very little additional effort, you can get a correct result.

What is going to happen to your case when the opposing expert points out that you have used a formula that is almost never correct?

"My Turn At The Wheel"

... is a forum for opinion and commentary. The opinions expressed may not reflect a widely accepted or adopted view or position but may be meaningful to the author and many in the community. In any case, they are offered to generate discussion and or debate within the community. Your responses or submissions for this periodical recurring feature are invited - editor@collisionpublishing.com

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

bstract The research problem concerns the range of protection provided by safety and protection technologies considering the high levels of motorcycle crash injuries, fatalities and related costs. Evaluative methods included descriptive statistics and compiling lists and categories of motorcycle safety technologies, identifying, locating and estimating safety and protection provided for the motorcycle or rider and assessing the potential for the technology to reduce crashes, injuries, fatalities and costs. Technologies include helmets, clothing, eye and foot protection, vests, reflective materials, seat belts/fall-bars/enclosure scooters, and airbags and enclosures. The results of the study suggest a greater degree of safety and protection, and hence cost reduction, provided by the motorcycle airbag equipped enclosure followed by the seat belts/fall-bars/enclosure scooters and helmets compared to other motorcycle safety technologies. Large standard deviations were found when comparing percent protection provided by different technologies. This study provides Industry with a comparable study of motorcycle safety and protection technologies.

A

roblem Motorcycle crashes, collisions, accidents and spills generally occur when the motorcycle and rider are moving at various speeds. Such motorcycle crashes, collisions, accidents and spills that occur when the motorcycle is moving at fastest

P

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speeds generally may lead to more serious injury or a higher probability of fatality. Many other factors contribute to the resulting motorcycle rider injury or fatality in crashes, collisions, accidents and spills including, but not limited to the direction or angle at which the motorcycle or rider is contacted, the secondary impact of the motorcycle or rider, the speed of other vehicle involved, other surfaces or objects contacted, the area of the rider’s body impacted, vision, highway and weather conditions, driver condition, etc.

Additional safety and protection of motorcycles and riders is required for situations involving law enforcement, national defense, security and first responders. In these situations, objects may be thrown, projected or shot at the motorcycle and rider from various angles and directions. In many situations, these riders must ride their motorcycles in undesirable weather conditions such as rain, intense heat and sunshine, sleet, snow and hail, and extreme cold conditions. General consumers as well as law enforcement, national defense, security and first responder motorcycle riders experience undesirable weather conditions and require a level of protection and safety in such conditions. In all motorcycle rider

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Ranges of Safety Provided by

Safety Technologies Used For Reducing Motorcycle Crashes, Fatalities, Injuries and Loss William Belisle

situations, general and basic motorcycle safety, including injury and fatality reduction technologies, are required.

Statistics indicate that the rider being detached from the motorcycle in crashes, collisions, accidents and spills has contributed to rider injury and fatalities. Statistics also indicate that lack of motorcycle and rider visibility by other automobile drivers has contributed to motorcycle crashes, collisions, accidents and spills.

Two of the general categories in which motorcycle riders may be included are ‘for pleasure’ and ‘for necessity’. The authors recognize the fact that motorcycle riding for pleasure may be a necessity for some riders as motorcycle riding as a necessity may be a pleasure for some riders. Law enforcement, military, security and first responder type motorcycles and riders are considered ‘for necessity’ working motorcycle and riders are required to work twenty-four hours a day, seven days a week, long road hours, higher speed situations, in all types of weather, in all types of challenging or dangerous situations, or possibly even under attack. A high level of motorcycle and rider protection may be required for such motorcycle riding working environments.

Four, six and sixty law enforcement officers died in motorcycle crashes in 2005, 2006 and between 1995 and 2004, respectively.1 The smaller size of motorcycles relative to other vehicles contributes to difficulty with other drivers seeing the motorcycles; this being a contributing factor in crash situations.2 Motorcycle crash fatalities have increased over the last nine years reaching 4,810 in 2006 and many crashes involved another vehicle, non-interstate roadways, intersections and the motorcycle striking the left side of a turning automobile.2,7 In 2008, the U.S. Department of Defense reported wenty-five military service members died in off-duty mo-

torcycle crashes and the Marine Corps lost nineteen service members to motorcycle crashes in 2007 noting high fuel prices as one of the reasons for higher motorcycle usage.3,6 Motorcycle training has become mandatory for many military installations.3,6 In 1999, $161 and $155 million were paid for motorcycle crashrelated costs for property damage and bodily injury losses; most of which was caused by other drivers.4 In 2006, motorcycle crash fatalities were thirty-five times higher than those of other vehicles, and it was noted that motorcycles are less visible and stable than other vehicles and because of the lack of protection as in automobiles, a higher probability of injury or death exists.5 Helmet use is important to motorcyclists and many states have no motorcyclist helmet requirement. In 2007, large percentages of motorcycle crashes involved single and multi-vehicle crashes and 5,037 individuals were killed.5 In 2008, U.S. Army Guide to Motorcycling reported over four million registered motorcycles and thirty-three thousand military registered motorcycles on Army installations, motorcycles provide virtually no protection in crashes, most motorcycle crashes result in injury or fatality, motorcycles have no door beams or roofs for impact and roll-over as do other vehicles, wind shield wipers contribute to better visibility in rain and snow, motorcycle size causes less visibility to other drivers, motorcycles are less stable than other four-wheel vehicles and motorcycles suffer compared to automobile occupant safety.6 The U.S. Army Guide to Motorcycling also reported high motorcyclist visibility requirements for military personnel in addition to helmet, eye protection, jacket, pants, gloves, boots, rain suit meeting required standards.6 Helmets could have saved 700 lives annually and motorcyclists perceive helmets as spoiling the ride.7 More than one million automobile deaths have occurred since 1978 costing approximately $164 million annually or $5 trillion over the same period.7

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In 2001, 2002 and 2003, 3,181, 3,270 and 3,661 motorcyclists were killed in traffic crashes.9 Louisiana motorcycle fatality rate, as an example of increasing fatalities, increased by 170% from 1997 to 2002.9,10 Motorcyclists’ age, motorcycle engine size and weakening helmet laws contributed to many of the fatalities. Motorcycle fatalities cost motorcyclists and citizens $1,020,889 per person (excluding severe and moderate injuries and complaints) in higher taxes, higher insurance premiums and highway delays.10 In 2003, 996,000 motorcycles were sold and 1,225,356 motorcycles were exported in 2004.11,12 Sgt. Richard S. Titiusy (December 2000) at www.ridesafer.com, states that some of the above described safety equipment is recommended and some is mandatory for the military and for motorcyclists on military installations.

“The positioning of the safety and protection devices may contribute to the degree of safety and protection provided.”

Motorcyclist safety equipment potentially protects the motorcyclist in crash situations and from harmful or undesirable conditions.

The positioning of the safety and protection devices may contrib-

ute to the degree of safety and protection provided. Present motorcyclist safety equipment includes, and is not limited to, helmets, leather clothing and accessories (pants, jackets, gloves, etc.), elbow and knee pads, an airbag jacket, eye protection (goggles/glasses, fairings, helmet face shields, etc.), seatbelts, boots, reflective tape, accessories and clothing, horns, lights, front and rear light modulators, and LED lighting (see Table 1 for general examples). Helmets are the most important motorcyclist safety equipment and provide head protection in crash situations. Leather clothing and accessories provide protection for the upper and lower bodies and the airbag jacket protects the upper body. Seatbelts and protective bars prevent motorcyclist from falling from the vehicle and keep the rider from striking the riding or other bar proximity surfaces directly from the side directions and vice versa. Boots provide protection of feet, reflective tape etc., lights, modulators, and LED lighting improve motorcycle visibility, and horns provide sound warnings and awareness. Some motorcycles are equipped with leg and foot protection equipment or accessories. Helmet laws vary from state to state and military bases recommend and require some of the described safety equipment.13 Recently, motorcycle safety technologies have been expanded to motorcycle airbags and motorcycle enclosures for motorcyclists and motorcycle protection and enhanced motorcycle visibility.

Motorcycle airbag systems appear to add an additional degree of protection of riders and motorcycles regarding crash-related injuries and fatalities. Numerous technologies describe enclosures, covers, and apparatus for motorcycles or two-wheeled, automotive vehicles14,15,16 providing protection from environmental conditions and crashes14,15 and include enclosure transparency.14,15,16 Motorcycle airbag equipped enclosures were introduced in 200017. Other enclosure products and technologies, lighting devices, mirrors, and water (or other material) removing or water (or other material) repelling devices for automotive vehicle enclosures will be added later 18,19,20,21,22,23,24,25.

Motorcycle Safety Device or Technology Categories Rider Clothing & Body Wear (other than headgear; Kevlar may be considered)

Rider Head Gear

Motorcycle Accessories

Rider Restraints to Motorcycle Motorcycle Airbag Frame *Motorcycle Structure/ Protection Systems Frame Enhancement

Leather Jackets

Helmets

Fairings

Seatbelts, Fall-bars, and vertically surrounding Frame (C-1), covered scooter

Leather or Kevlar Pants

Eye Protection

Foot Guards

Handlebar-positioned airbags

Reflective Materials and Lights

Gas tank positioned airbags

Leather Gloves Leather Vests

Rear seat-attached airbags

Leather Shirts *Airbag Vest/Jacket Reflective Materials and Lighting Table 1

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Airbag Equipped Enclosures

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Figure 1. Front quarter view (top) and front view (bottom) of the airbag equipped enclosure for motorcycles with circular dark-colored airbag strips at the head, mid-body and lower body levels within the enclosure.

The motorcycle airbag equipped enclosure17 provides vertical and horizontal airbag strips located in the upper, middle, and lower area of the enclosure (see Figure 1) with temperature and environmental control, varying degrees of "more than one way", "visibility other than transparent", and transparent types of visibility into or out of the enclosure as well as increased visibility by other drivers, varying degrees of "luxury and comfort" and communications, audio and audiovisual systems. Figures 1 and 2 show the front quarter view and the front view of the motorcycle airbag equipped enclosure with no doors or portals for high-risk level motorcycle riding, showing the black circular strip-type airbag systems within the enclosure.

In 2005, Japan’s Honda Motor announced the introduction of handlebar positioned airbags to protect the driver from the head to lower back and suitable shape of the airbags (BMW motorcycles also). Other such technologies included frontal protection airbag on the steering handle 26, airbag positioned at the front portion of a fuel tank27, airbag positioned at the front end of the frame of a motorcycle28, airbag positioned at the frontal area of a motor scooter seat29, airbag positioned about the steering handle and at the front end of the main frame30, airbag on/atop a dummy fuel tank31, airbag positioned just under the front of the seat32, airbag positioned in front of the fuel lid33 and airbags connected to the motorcycle frame, handlebars, gas tank, near the riders abdomen www.collisionpublishing.com

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area, varying shapes for the front-of-the-rider-positioned airbag, and tethering to attached airbag to the motorcycle itself 34,35.

Motorcyclist environmental protective equipment protects the motorcyclist in undesirable environmental conditions. Such conditions may include, but are not limited to, rain, snow and falling ice, cold and heat, and glare from the sun. Present motorcyclist environmental protection equipment includes, and is not limited to, helmets, leather clothing and accessories (pants, jackets, gloves, etc.), and eye protection (goggles/glasses, fairings, helmet face shields, etc.). Helmets some heating and cooling systems, and leather clothing and accessories provide a very limited degree of protection from rain, snow and falling ice, cold and heat. Eye protection, including goggles/glasses, fairings, and helmet face shields, provide a limited degree of protection of the face and eyes from rain, snow and falling ice, and (possibly) glare (except for tinted types) from the sun. The motorcycle airbag equipped enclosure provides varying degrees of protection from glare and sunshine, rain, snow and falling ice, heat and cold, large and small moving objects, one- or two-way viewing, and also enhances motorcycle visibility. ethod The research hypothesis is “there is a broad range of safety and protection provided by motorcycle safety and protection technologies”. The hypothesis is based on a) the specific intended purpose of the safety and protection technology and b) the positioning of the safety and protection technology on the motorcycle or the motorcyclist in crash or collision and related situations. The hypothesis suggests more or less safety and protection provided by each of the technologies. Con-

M

sidering the motorcyclist body and the motorcycle, evaluation of the tabulated device and technology data included approximated protection levels of a) no protection = 0% protection, b) no protection to moderate protection = 25% protection, c) moderate protection = 50% protection, d) moderate to maximum protection = 75% protection, and e) maximum protection = 100% protection.

Descriptive statistics were used to analyze data. The resulting information was used to estimate the degree of protection provided by each technology. The higher the estimated percent protection the more protection provided for the rider and motorcycle. Road, highway and interstate speeds and conditions at 50 mph or higher were considered.

The methodology included a) compiling a list of available devices and technologies that can be used to reduce motorcycle crash-related injuries, fatalities and costs b) the identification and location of devices and technologies on the motorcycle or rider and c) the potential for the device or technology to reduce and minimize motorcycle crashes, collisions, accidents and spills as well as related injuries, fatalities and costs. The data evaluation considers the general purpose of the device, the position of the device, and the general area of the rider’s body for which the safety and protection is provided. The methodology also included listing devices and technologies used for protecting motorcycles and riders in law enforcement, national defense, security and first responder activities, attacks, and undesirable weather and environmental conditions.

Charts 2a-h were created to show the identified motorcycle crash, collision, accident and spill and injury and fatality reducing devices and technologies data, and allow an evaluation of the devices and technologies based on their relationship to a) the ability to provide safety and protection regarding the area of the motorcycle that may

Chart 2A: Protection provided in frontal, side, back and top crash impacts

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Chart 2B: Area of motorcycle body possibly struck in crash or collision

Chart 2C: Secondary impacts in crashes and impacts www.collisionpublishing.com

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Chart 2D: Additional protection needed by law enforcement, defense, security, and first responders

be impacted including front, side, back, or top, b) the area of the motorcycle rider’s body that may be struck including upper body, mid-body and lower body, c) rider protection provided after the initial crash or collision impact, d) additional protection needed by law enforcement, defense, security and first responder type personnel, e) protection from projected objects approaching from various directions, f ) protection from undesirable weather and environmental conditions, g) the enhancement of motorcycle visibility to other motorists, and h) eliminates or minimize rider detachment from motorcycle. Chart 2.c considers initial impact with another automobile or objective and a subsequent impact with a second surface or object. Charts 2g-h considers enhances (100%) or does not enhance (0%) motorcycle visibility and minimizes (100%) or does not minimize (0%) rider detachment from the motorcycle, respectively. esults Chart 2a shows reflective materials, lights and fairings, except for 25% protection provided by fairings in frontal collisions, provide 0% protection in frontal, side, back and top impacts in motorcycle collisions. Leather or other jackets, etc., eye protection and foot guards provide 25% protection for the same and airbag vests and helmets provide 50% protection for the same. The fall-bars, seatbelt and frame proved 75% protection in frontal, side, back and top impacts while handle-bar-

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positioned and gas tank positioned airbags both provide 75% protection in frontal impacts, 0% protection in side and top impacts and the handle-bar-positioned airbag may also provide 25% protection in back impacts. The airbag equipped enclosures provide 100% protection in frontal, side, back and top impacts in collisions. The standard deviation for frontal, side, back and top crash impacts were between 32 and 33.5 for each of the technologies.

The average percent protection provided by each technology front, side, back and top impacts ranged from 0% to 25% protection for leather and other jackets etc., eye protection, fairings, foot guards, and handle bar-, gas tank- and rear seat positioned air bags, 26% to 50% for air bag vests and helmets, 50% to 75% for fall-bars, seat belts and frame, and 100% for airbag equipped enclosures.

Chart 2b shows reflective materials and lights provide no protection for the upper, mid or lower body in collisions. Leather or other jackets etc. and fairings provide 25% protection, airbag vests provide 50% protection, and fall-bars, seatbelts and frame provide 75% for the same. Helmets provide 75% protection for the upper and 0% protection for the mid and lower body while eye protection provides 50% protection for the upper body and 0% for the mid and lower body. Fall-bars, seatbelts and frame provide 75% protection for upper, mid and lower body in collisions. Handlebar, gas-tank, and rear seat positioned airbags each provide 75% protection for upper and mid body and 0% protection for lower

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Chart 2E: Protection from objects approaching from the front, side, rear, and top

body in collisions. The airbag equipped enclosures provide 100% protection for upper, mid and lower body in collisions. Standard deviations ranged from 32 to 35.6 for upper body, mid-body and lower body protection provided by all of the technologies. The average percent protection provided for upper, mid-body and lower body ranged between 0% and 25% for leather and other jackets etc., eye protection, reflective materials, fairings, and foot guards, 25% to 50% for air bag vests, helmets, and handle bar-, gas tankand rear seat positioned airbags, and 50% to 75% for fall bars, seat belts and frames, and 75% to 100% for air bag equipped enclosures.

Regarding protection in secondary crash or collision impact, Chart 2c shows reflective materials and lights, and handle-bar-, gas tankand rear seat-positioned airbags provide 0% protection. Leather or other jackets etc., airbag vests, eye protection, fairings and foot guards provide 25% protection, helmets and the fall-bar, seat belt and frame provide 75% protection for the same. The airbag equipped enclosure provides 100% protection in secondary crash or collision impact. The standard deviation for percent protection provided for secondary crash impacts was 33.9 while the average percent protection provided for each of the technologies in secondary impacts was 31.3%.

Chart 2d shows leather or other jackets etc., airbag vests (except for 25% protection in high-speed chases), eye protection (except for 25% protection from moving objects and projectiles), reflective materials and lights, fairings (except for 25% protection from moving or objects or projectiles), foot guards, and fall-bars, seat

belts and frame, and handle-bar-, gas tank- and rear seat positioned airbags (except for 25% protection by each in high-speed chases) provide 0% protection from gunfire, moving objects or projectiles, high-speed chases and chemicals, explosives and intense environmental conditions. Helmets provide 0% protection from gunfire and chemicals etc. and provide 25% and 75% protection from moving objects and projectiles and high-speed chases, respectively.

Airbag equipped enclosures provide 100% protection from gunfire, moving objects and projectiles, high-speed chases, and chemicals, explosives and intense environmental conditions. The standard deviation ranged from 28 to 32 for the average protection provided by all technologies for gunfire, moving objects/projectiles, high speed chases and chemicals, explosions and extreme environmental conditions. The average percent protection provided by individual technologies ranged from 0% to 25% for all technologies except for the airbag equipped enclosure which provided 100% protection.

More evidence of protection from moving objects and projectiles is shown in Chart 2e in that leather or other jackets etc., airbag vests, eye protection, reflective materials and lights, foot guards, and handle-bar-, gas tank-, and rear seat-positioned airbags provide 0% protection from objects approaching from front, side, rear and top. The airbag equipped enclosure provides 100% protection from objects approaching from the front, side, rear or top.

The standard deviation ranged from 29.2 to 34.5 for the average percent protection provided by all technologies for front projected, side projected, rear projected and top projected objects. The average protection provided by individual technologies for front

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Chart 2F: Protection from indesirable weather and enviornmental conditions

Chart 2G: The enhancement of motorcycle visibility

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Chart 2H: Minimizes motorcyclist detachment from motorcycle in crash or collisions

projected, side projected, rear projected and top projected objects ranged from 0% to 25% for leather and other jackets etc., air vests, eye protection, reflective materials, fairings, foot guards, fall bars, seatbelts and frame, and handle bar-, gas tank-, and rear seat-positioned airbags, 25% to 50% for helmets and 75% to 100% for air bag equipped enclosures.

other jackets, etc., airbag vests, helmets, eye protection, handlebar-, gas tank- and rear seat-positioned airbags do not enhance motorcycle visibility. The standard deviation was 51.5 for all technologies for the percent enhanced visibility provided and the average percent provided by all technologies was 41.7% enhanced visibility.

Chart 2f shows airbag vests, reflective materials and lights, foot guards, and handle-bar-, gas tank- and rear seat positioned airbags provide 0% protection from rain, snow, glare/sunshine, cold, heat and hail. Leather or other jackets provide 25% protection from rain, snow, cold and heat and 0% protection from glare/sunshine and hail. Helmets provide 25% protection in rain, snow and hail and 0% protection from glare/sunshine, cold, heat and hail. Eye protection provides 75% protection from glare/sunshine and 0% protection from rain, snow, cold, heat and hail. Fairings and fallbars, seat belts and frame provide 25% protection from rain and snow and 0% protection from sunshine/glare, cold, heat and hail (except for 25% protection by fairings from hail). Airbag equipped enclosures provide 100% protection from rain, snow, glare/sunshine, cold, heat and hail. The standard deviations ranged from 28.0 to 34.5 for the average protection provided by all technologies for rain, snow, glare/sunshine, cold, heat and hail. The average protection provided by individual technologies ranged from 0% to 25% protection for leather and other jackets, air vests, helmets, eye protection, reflective materials, fairings, foot guards, fall bars, seat belts, and frame, handle bar-, gas tank- and rear seat-positioned airbags, and 75% to 100% for airbag equipped enclosures.

Chart 2h shows leather or other jacket etc., airbag vests, helmets, eye protection, reflective materials and lights, fairings, and foot guards do not minimize the chances of the rider being thrown or detached from the motorcycle. Handle bar-, gas tank- and rear seat positioned airbags provide 25% protection of the rider being thrown or detached from the motorcycle. The fall-bars, seat belt and frame and the airbag equipped enclosure provides 100% protection of the rider being thrown or detached from the motorcycle.

The standard deviation was 37.6 for all technologies protection provided against the motorcyclist being detached from the motorcycle and the average percent provided by all technologies for the same was 22.9.

As shown in Chart 2g, reflective materials and lights, fairings, foot guards, fall-bars seat belts and frame, and airbag equipped enclosures enhance motorcycle visibility by other drivers. Leather or

iscussion The data is discussed regarding the potential safety and protection provided to the rider and the motorcycle, along with the safety and protection associated with the location of the safety and protection device and the related potential safety and protection provided for the rider and the motorcycle.

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As shown in Chart 2a, the motorcycle airbag equipped enclosures provides maximum protection of the motorcycle rider and the motorcycle in frontal, side, back and top impacts in crash or collision situations. The C-1 scooter provides moderate protection to maxi-

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mum protection in similar situations. Regarding frontal, side, back and top impacts in crash or collision situations, handle bar- and gas tank-positioned airbags provide moderate protection to maximum protection for frontal impacts and rear seat-positioned airbags provide moderate to maximum protection from back impacts. Regarding frontal, side, back and top impacts in crash or collision situations, airbag vests provide moderate protection (frontal, side and back) and no protection to moderate protection (top), leather and other clothing provide no protection to moderate protection in frontal, side, back and top impacts, eye protection and foot guards provide no protection to moderate protection in frontal, side, back and top impacts, and generally reflective materials and lighting and fairing (except for no protection to moderate protection for frontal impacts) provide no protection.

“The motorcycle airbag equipped enclosures provides maximum protection for the rider’s upper, mid-, and lowerbody in crashes or collisions.”

As shown in Chart 2b, the motorcycle airbag equipped enclosures provides maximum protection for the rider’s upper, mid-, and lower-body in crashes or collisions. Regarding motorcycle crashes and collisions and the rider’s upper body, the helmet, C-1 scooter, and handle bar-, gas tank- and rear seat-positioned airbags provide moderate protection to maximum protection, airbag vests provide moderate protection, leather and other clothing and fairings provide no protection to moderate protection, and reflective materials and lights provide no protection. Regarding motorcycle crashes and collisions and the rider’s mid-body/torso, the C-1 scooter and the handle bar-, gas tank- and rear seat-positioned airbags provide moderate protection to maximum protection, airbag vests provide moderate protection, leather and other clothing, helmets and fairing provide no protection to moderate protection and eye protection, reflective materials, lighting and foot guards provide no protection. Regarding motorcycle crashes and collisions and the rider’s lower body/legs and feet, foot guards and the C-1 scooter provide moderate protection to maximum protection, airbag vests provide moderate protection, leather and other clothing, helmets, and fairings provide no protection to moderate protection and eye protection, reflective materials, lighting and handle bar-, gas tankand rear seat-positioned airbags provide no protection.

As shown in Chart 2c, and regarding secondary crash or collision impacts, the motorcycle airbag equipped enclosures provides maxi54 Collision

mum protection and the helmet and C-1 scooter provides moderate protection to maximum protection for the same. Leather and other clothing, the airbag vest, eye protection fairings and foot guards provide no protection to moderate protection regarding secondary motorcycle crash or collision impacts. Reflective materials, lighting and handle bar-, gas tank- and rear seat-positioned airbags provide not protection from secondary crash or collision impacts.

As shown in Chart 2d, the motorcycle airbag equipped enclosures provides maximum protection needed by law enforcement, defense, security and first responder type personnel including gunfire, moving objects and projectiles, high-speed chases and chemicals, explosions, and intense environmental conditions. The helmet provides moderate protection to maximum protection in high-speed chases.

Airbag vests, the C-1 scooter, and handle bar-, gas tank- and rear seat-positioned airbags provide no protection to moderate protection in high-speed chase situations, and helmets, eye protection, fairings, and the C-1 scooter provide no protection to moderate protection from moving objects and projectiles.

As shown in Chart 2e, the motorcycle airbag equipped enclosures provides maximum protection of the motorcycle rider and motorcycle from projected objects approaching from various directions including the front, side, rear and top. The motorcycle helmet provides moderate protection to maximum protection from projected objects approaching from various directions including the side, rear and top. Leather clothing, airbag vests, eye protection, reflective materials, lights, fairings (side, rear, top), foot guards, handle bar-, gas tank- and rear seat-positioned air bags provide no protection from projected objects approaching from the front, side, rear or top.

As shown in Chart 2f, only the motorcycle airbag equipped enclosures provides maximum safety and protection of motorcycle riders and motorcycles from undesirable weather and environmental conditions including rain, snow, glare and sunshine, cold, heat and hail. Eye protection provides moderate protection to maximum protection of eyes in such conditions and helmets provide protection to the majority of the head only considering rain, snow and hail. Leather and other clothing provide no protection to moderate protection from rain, snow, cold and heat, fairings provide no protection to moderate protection from rain and snow and hail, and the C-1 scooter provides no protection to moderate protection from rain, snow and hail. Airbag vests, eye protection (except glare/sunshine), reflective materials, lights, foot guards, and handle bar-, gas tank- and rear seat-positioned air bags provide no protection from rain, snow, glare/sunshine, cold, heat and hail.

As shown in Chart 2g, reflective materials and lights, fairings, foot guards, the C-1 Scooter and the motorcycle airbag equipped enclosures motorcycle safety and protection technologies enhance the visibility of the motorcycle and rider. The motorcycle airbag equipped enclosure provides the greatest enhanced visibility because of the size and nature of the airbag equipped enclosure, the encompassing shape and reflective and lighting capacity. Leather or other clothing, airbag vests, helmets, eye protection, reflective materials, fairings and foot guards, and handle-bar-, gas tank- and rear seat-positioned airbags do not (significantly) enhance the visibility of the motorcycle or rider.

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As shown in Chart 2h, only two motorcycle safety and protection technologies minimize the chances of the motorcycle rider being thrown or detached from the motorcycle including the C-1 Scooter and the motorcycle airbag equipped enclosures. The C-1 Scooter uses seat belts to restrain the rider to the motorcycle frame and the motorcycle equipped enclosure uses airbags positioned within an enclosure to restrain the rider within the enclosure. Handle-bar-, gas tank- and rear seat-positioned airbags may provide no protection to moderate protection regarding the rider being thrown or detached from the motorcycle and leather or other clothing, airbag vests, helmets, eye protection, reflective materials, lights, fairings and foot guards do not minimize the chances of the rider being thrown or detached from the motorcycle.

There is a direct and considerably linear relationship between the degree of motorcycle crash or collision related injuries or fatalities and the cost for such injuries and fatalities. These costs may be associated with personal costs, medical costs, insurance costs, and law enforcement costs and public costs. It is therefore reasonable to suggest that as motorcycle crashes and collisions are reduced and as motorcycle crash and collision related injuries and fatalities are reduced that the overall costs (personal, medical, insurance, law enforcement and public) will also be reduced. Each of the motorcycle safety and protection technologies discussed in this paper contribute, to some degree, to a reduction of crash and collision incidents or to a reduction of related injury or fatality in crash or collision situations. We therefore deduce that there is a reduction in costs related to crashes or collisions and crash or collision related injuries and fatalities. Because of the maximum protection provided in all of the crash and collision related injuries and fatalities situations by the motorcycle airbag equipped enclosures, the motorcycle airbag equipped enclosures contributes most out of all motorcycle safety and protection technologies to a reduction in motorcycle crash or collision related injuries and fatalities. Secondly, the C-1 scooter and helmets contribute secondarily to a reduction in motorcycle crash or collision related injuries and fatalities, and therefore contribute secondarily, compared to the motorcycle airbag equipped enclosure, to a reduction in motorcycle crash or collision related injury and fatality costs. mpact on Industry This paper provides industry with a succinct, convenient and readily available compilation of available motorcycle safety and protection devices and technologies with supporting background information about each. This paper also informs the industry as to the general scope of safety and protection provided to motorcycle riders by each of the devices and technologies. This paper also provides industry with a comparison of the potential motorcycle rider safety and protection associated with each device and technology. Consumers and professionals may benefit from the information in this paper regarding possible uses or combinations of safety devices and technologies in order to achieve a maximum degree of motorcycle rider safety and protection. Industry may also be able to determine the best motorcycle safety and protection technologies to use for consumers as well as for law enforcement, security, defense and first-responder type riders.

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Motorcycles use much less gas than automobiles. Regarding the riding environment, motorcycles riding environments are much

different from automobile riding environments. The motorcycle airbag equipped enclosure product encloses the motorcycle rider within a hard shell, can be used for two-, three- and four-wheeled vehicles opening the possibility of automobile-like covered or enclosed motorcycles, and can be designed with conventional type automobile parts and equipment such as steering columns and steering wheels, and gas, clutch (if not an automatic transmission motorcycle) and break peddles. ummary The best potential motorcycle rider and motorcycle safety and protection technology for road, highway and interstate driving speeds and for law enforcement, defense, security and first responder type motorcycle riding, considering the positioning of the safety and protection device, is the motorcycle airbag equipped enclosure. The motorcycle airbag equipped enclosure is the only safety and protection technology that provides maximum protection of the rider and the motorcycle a) in frontal, side, back and top impacts, b) from upper-, mid, and lowerbody and feet injury, c) in secondary crash or collision impacts, d) from law enforcement, defense, security and first responder related situations such as gun fire, moving objects and projectiles, highspeed chases and chemicals, explosions and intense environmental conditions, e) from projected objects approaching from various directions including front, side, rear and top, f ) from undesirable weather conditions including rain, snow, glare/sunshine, cold, heat and hail, g) by enhancing motorcycle and rider visibility, and h) by minimizing the chances of the rider being detached or thrown from the motorcycle in motorcycle crash or collision situations.

The next best potential motorcycle rider and motorcycle safety and protection technology in similar situations is the BMW C-1 scooter. The third best potential motorcycle rider and motorcycle safety and protection technologies in similar situations are the helmet and the handle bar-, gas tank- and rear seat-positioned air bags.

The motorcycle airbag equipped enclosure, the C-1 scooter, and the helmet and the handle bar-, gas tank- and rear seat-positioned air bags contribute most and in relative order to a reduction in motorcycle crash or collision related costs.

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Large standard deviations were found for each set of data analyzed including a) each individual technology analyzed per crash or collision situation investigated as well as for b) each motorcyclist or motorcycle impact category within each crash or collision situation per technology. Such large standard deviations may suggest, as does the research hypothesis “there is a broad range of safety and protection provided by motorcycle safety and protection technologies.” Such large standard deviations may also reflect the use of a limited number of data points including estimated percent protection for all technologies of 0, 25, 75 and 100.

eferences 1. U.S. Department of Justice, 2008. Uniform Crime Reporting Program, Law Enforcement Officers Killed and Assaulted 2005.

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2. National Highway Traffic Safety Administration, 2008. Fact Sheet, 2008 Motorcycle Safety Awareness Planner.

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3. U.S. Department of Defense, 2008. American Forces Press Service News Articles, “Motorcycle, Vehicle Accidents Dominate Off-Duty Summer Fatalities”.

4. U.S. Department of Transportation, National Highway Traffic Safety Administration, 2008. “Motorcycle Vehicle Insurance in the United States”.

5. Insurance Institute for Highway Safety, 2008. Highway Loss Data Institute, “Fatality Facts – Motorcycles” 6. Whybike.com, 2008. “US Army Guide to Motorcycling”, www.whybike.com/motorcycle194.htm.

7. Sitenews.com, 2008. “A Fatal Freedom: Deaths in motorcycle crashes on rise”, Thomas Hargrove, Scripps Howard News Service, May 28, 2006.

8. Big Bend Bikers For Freedom, 2008. “Motorcycle safety bits and pieces”, 8.23.08, www.bigbendbikersforfreedom.com.

9. U.S. Department of Transportation, National Highway Traffic Safety Administration, 2003. Traffic Safety Facts 2003, DOT HS 809 764, www.nhtsa.dot.gov.

10. Schneider, Helmut, 2003. An Analysis of Motorcycle Crashes 1996-2002, Louisiana State University, Louisiana Traffic Crash Reports, http://lhsc.lsu.edu, or http://isds.bus.lsu.edu.

11. Motorcyclist Magazine, 2003. “U.S. Motorcycle Sales Set to Top One Million Units This Year”, Motorcycle Industry Council.

12. Japan Automobile Manufacturers Association (JAMA), 2004.

Current Statistics, www.jama.org or www.jama.org/statistics/ quickstats/.

13. Titiusy, R. S., 2000. www.ridesafer.com, (December 2000).

14. Bothwell et al., 1997. “Motorcycle with an Enclosed Body and Support Assembly”, U.S. Patent and Trademark Office Patent Number 5685388.

15. Kelley, R. F., 1976. “Transparent Cover with Connecting Devices for Motorcycles and Riders”, U.S. Patent and Trademark Office Patent Number 3979147.

16. Bunau-Varilla, E., 1915. “Wind Dividing Apparatus for Transport Vehicles with Kinematics Equilibrium”, U.S. Patent and Trademark Office.

17. Belisle, W. R., 2000. “Fairing and Fairingless Enclosures for Two-, Three-, and Four- Wheel Automotive vehicles/Riders/Passengers/Loads (FFE)”, U.S. Patent and Trademark Office Patent Number 6,017,076.

18. Stobar, L. T., 1978. “Motorcycle Fairing-Windshield Assembly”, U.S. Patent and Trademark Office Patent Number 4089556.

19. Johnson, et al., 1982. “Motorcycle Fairing Body Extender”, U.S. Patent and Trademark Office Patent Number 4331358.

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20. Yoshimura et al., 1994. “Fairing for a Motorcycle”, U.S. Patent and Trademark Office Patent Number 5330029.

21. Buell, E., 1990. “Motorcycle Fairing”, U.S. Patent and Trademark Office Patent Number 4,964,484.

22. Yamada et al., 1990. “Exterior Shell of a Motorcycle Front Fairing Unit”, U.S. Patent and Trademark Office Patent Number Des. 311,715.

23. Jaeke, V., 1977. “Motorcycle Fairing”, U.S. Patent and Trademark Office Patent Number D243079.

24. Hickman, J. S. 1982. “Motorcycle Fairing”, U.S. Patent and Trademark Office Patent Number 4355838.

25. Sakuma, T. S., 1988. “Motorcycle with Fairing”, U.S. Patent and Trademark Office Patent Number 4776422.

26. Kuroe et al. 2005. “Airbag apparatus for a compact vehicle”, (Assignee – Honda Giken Kogyo Kabushiki Kaisha, Tokyo), U.S. Patent and Trademark Office Patent Number 6,846,009.

27. Yanagibashi et al. (2005. “Airbag system”, (Assignee – Honda Giken Kogyo Kabushiki Kaisha, Tokyo, U.S. Patent and Trademark Office Patent Number 6854762.

28. Yanagibashi et al. 2006. “Airbag system”, Assignee - Honda Giken Kogyo Kabushiki Kaisha, Tokyo, U.S. Patent and Trademark Office Patent Number 6,991,254.

29. Yamazaki et al. 2005. “Air bag system in scooter type vehicle”, Assignee – Honda Giken Kogyo Kabushiki Kaisha, Tokyo, U.S. Patent and Trademark Office Patent Number 6,932,379.

30. Yamazaki et al., 2006. “Airbag system”, Assignee – Honda Giken Kogyo Kabushiki Kaisha, Tokyo, U.S. Patent and Trademark Office Patent Number 6,991,254.

31. Akiyama et al., 2005. “Airbag apparatus for a small size vehicle”, Assignee – Honda Giken Kogyo Kabushiki Kaisha, Tokyo, U.S. Patent and Trademark Office Patent Number 6971666.

32. Akiyama et al., 2006. “Airbag apparatus”, Assignee – Honda Giken Kogyo Kabushiki Kaisha, Tokyo, U.S. Patent and Trademark Office Patent Number 7,029,029.

33. Horiuchi, 2007. “Air bag support belt cover structure”, Assignee - Honda Motor Co., Ltd, Tokyo, U.S. Patent and Trademark Office Patent Number 7,255,363.

34. Miyata, 2006. “Airbag device and motorcycle with the airbag device”, Assigned to the Takata Corporation, U.S. Patent and Trademark Office Patent Number 7,104,568.

35. Miyata, 2008, “Motorcycle” Assigned” to the Takata Corporation. U.S. Patent and Trademark Office Patent Number D572,630.

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Cdr Based Evidence

Frequently Asked Questions William J. Melkonian Assistant District Attorney Essex District Attorney’s Office

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ver the past several years, the number of trial courts admitting CDR evidence has increased dramatically across the country. The number of appellate decisions during the same time period, however, has not increased in a corresponding fashion. Appellate decisions remain sparse, at least in the motor vehicle context. In fact, some of the more recent decisions concern civil suits in which EDR data from trains involved in collisions with motor vehicles have been admitted into evidence.

We should not be disappointed with this dearth of appellate decisions, for it means that courts routinely are accepting CDR evidence. Instead of viewing CDR evidence as alien in nature, courts see it as reliable, whether under the Daubert or Frye standard. In addition, just as defense attorneys initially fought prosecution attempts to introduce DNA evidence, only to begin demanding it as a way to exculpate their clients, so, too, have they changed their approach to CDR

evidence.

We should not consider this general acceptance of CDR evidence in the court system as an opportunity to relax our standards of reconstruction. Rather, we should view it a direct result of our tireless efforts and professionalism, and a sign of the challenges ahead, as systems become more complex and the opposition becomes more adept in its attacks. The focus will shift from admissibility to the human factor -- the analysis of the CDR data – just as that same focus has been the key to criticisms of analyses using traditional reconstruction techniques.

What follows is not legal advice or a treatise, but a recitation of my experience in interacting with police investigators in the context of criminal crash reconstructions in which CDR evidence is a live topic. I have intentionally omitted case or statutory cites, because each jurisdiction has its own laws on the issues and because no overarching federal law exists. I encourage you to seek legal advice from a local prosecutor; he or she will have the requisite knowledge of the applicable rules of search and seizure, of expert testimony, and of the rules of evidence, so as to assist you effectively.

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"Do I need a search warrant?"

Getting a search warrant is advisable because it can head off a multitude of problems with minimal effort. With a significant number of departments now using templates for their search warrant applications and affidavits, drafting a warrant takes less time than inquiring as to whether or not one is necessary. If you are intent on not writing a warrant for whatever reason, ask your prosecutor whether any of the justifications for warrantless searches exist (for example, the automobile exception or consent).

If you are investigating a case in a state with a CDR download statute requiring a warrant except in certain circumstances, pay attention to your exposure if you are found to be in violation of the law.

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One factor which might be determinative of your decision whether or not to apply for a warrant is whether you have the legal authority to tow the subject vehicle from the crash scene without a warrant.

If you do not have that authority and are going to write one for that purpose, why not include a paragraph or two for an EDR download?

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"How is a search warrant for CDR evidence different than that for a traditional reconstructionist’s examination of a vehicle?”

The legal requirements for a search warrant affidavit are the same whether one is requesting permission of a court to access box evidence or to perform a traditional examination of a motor vehicle.

That is, the affiant must state that: (1) there is probable cause to believe that a crime has occurred and (2) evidence of that crime will be located in the place to be searched. The affiant must reveal both the basis of his knowledge (how it is he or she knows the facts in the affidavit?) and establish the veracity of any statements. In a motor vehicle crash context, these later two requirements usually are met by naming the eyewitnesses to the defendant’s operation of the offending motor vehicle.

In a situation where one is seeking to access a box and its data, the affiant must additionally describe what an airbag control module (ACM) is, that it has a component which has a recording function (the EDR), and that the EDR can be accessed using the CDR tool.

The affiant should also indicate why the data is relevant and list the qualifications of the person who will be conducting the download and the analysis. A CDR search warrant affidavit requires this additional explanation because the science and the technique is not yet within the common knowledge of a magistrate, who, for instance, otherwise would know what fingerprints or paint sample comparisons are.

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“In investigating this particular case, I cannot say that anyone did anything wrong criminally. I want to get a search warrant for the ACM / EDR of each vehicle to see whether I can charge anyone. Do you think I can get a warrant?”

No. As stated above, you cannot get a criminal search warrant for a download – or for any other search of a vehicle – if you do not have probable cause to believe that a crime occurred.

You should check with your local prosecutor to see whether you have any statutory or common law administrative powers to investigate motor vehicle crashes. In Massachusetts, the courts have held that investigating officers may seize and search the equipment and safety features of a motor vehicle involved in a collision resulting in death; that case, though, was decided long before the advent of ACMs, EDRs, or CDRs and the courts have not further explained the holding in that context. Arson investigators in Massachusetts have the statutory authority to administratively investigate the origin and cause of fires. This authority includes the power to get administrative search warrants to re-enter a fire scene, even if criminal activity is not suspected. Do you have such administrative powers in your jurisdiction?

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“I don’t think anybody committed a motor vehicle

crime which contributed to this crash. I just think that one of the drivers was negligent in going a little too fast. Since negligence is "civil", there is "no crime", and I can’t get a warrant, right?”

Make sure you know what qualifies as criminal driving conduct under your local laws. In some states, such as Massachusetts, ordinary civil negligence can support a criminal charge of negligent operation or, even, motor vehicle homicide. Other states require more egregious driving behavior, akin to recklessness. Don’t miss an opportunity to access box data because you don’t know the law or fall into the trap of thinking this crash is "just" a civil matter.

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“I have the data from the module and an eyewitness’ statement. The case appears to be clearcut.

Do I have to do a traditional reconstruction?

The defendant probably is going to plead guilty, anyway!”

The short answer is, “Yes!” The longer answer is that, where possible, you should conduct a traditional reconstruction because box data simply is that: raw data without context. In addition, many times, that defendant you think is going to plead guilty, does not.

At trial, you will be “outed” for doing a sloppy investigation. Your CDR related evidence actually can make your case stronger by corroborating the results of your traditional reconstruction.

Also, jurors prefer witness driven cases, as opposed to those where the only proof is the result of a “machine.” (Just look at the number of times defendants charged with operating under the influence of alcohol are acquitted where the sole evidence is a breath test reading.) On top of all this, if you read your CDR report Data Limitations, you know that CDR analysis is not a substitute for traditional reconstruction.

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“I’ve done the traditional reconstruction. Do I really need to download the module (of a supported vehicle)?”

Yes, for the reasons stated in the answer to the previous question.

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A real question from the other day: “the owner of the offending vehicle, who was not the operator, consented over the telephone to a download of the module. Do I really have to get a warrant?”

If you insist on relying on an owner’s consent, get it in writing.

Unless the vehicle is stolen, the owner is closer to the defendant than he or she is to you. A long time goes by from the date of the arrest to the date of the hearing on the motion to suppress. Do not be surprised if the same owner who gave you consent over the phone suddenly does not recall doing that. Box evidence is too valuable. Don’t take a chance in losing a conviction.

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“I’ve downloaded the module in the defendant’s car and done a thorough examination. The car is a "total loss "and the defendant’s insurance company wants to take possession of it (and probably crush it). I can release it, right?”

No, at least not in Massachusetts. The issue is “spoliation” – the destruction or loss of potential evidence. If the defendant or his attorney has not had an opportunity to inspect the vehicle before you release it, you risk the case being dismissed if the defendant can make more than a speculative showing that he expected to find exculpatory evidence on or in the disposed vehicle.

In some states, such as Massachusetts, bad faith on the part of the government is not required. Where potential evidence is merely lost or stolen, the defendant still can file a spoliation motion and potentially have the evidence excluded or the case dismissed!

Check with your local prosecutor as to the status of the law in your jurisdiction.

?

“I have a trial coming up and received the most recent version of the CDR software two weeks ago. I don’t need to run the data with this most recent version, do I? What’s going to change?”

You always should run the data with the most recent version of the CDR software because each new version may include more capabilities or reformatted reports. As soon as you do run the data again, give the results to your prosecutor so that he or she can turn it over to the defense.

By not running the most recent version, you run the risk of missing potentially exculpatory evidence, which you must disclose immediately. Similarly, you may find something that makes your analysis stronger.

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66 Collision

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The mathematics of

Turns, ∑vasive Maneuvers, Lane Changes, and Passing Peter Bergh

I

ntroduction Our goal is to describe the movement of a vehicle as it goes through a turn, an evasive maneuver, a lane change, or a passing maneuver, which mandates two lane changes. Specifically, we want to know how far the vehicle travels and how long it takes the vehicle to complete the maneuver.

We note that a lane change is a turn in one direction followed by a turn in the opposite direction, such that the vehicle ends up in a direction parallel to its original direc-

tion and that the distance between the line formed by the original direction and the line formed by the final direction is L. Typically, L would be the width of a lane.

For an evasive maneuver, we know the distance D along the x axis and are interested in how far along the y axis the vehicle can get (i.e., how wide an obstacle can the vehicle avoid, given a speed and an acceleration). We call the maximum distance along the y axis yE.

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67

We make a few simplifying assumptions and define a coordinate system: Lateral acceleration (acceleration at right angles to the movement of the vehicle) is constant during a turn and zero when the vehicle is traveling in a straight line. We call the lateral acceleration during a turn aN, for acceleration in the direction of the Normal. In the case of a lane change, the lateral acceleration changes sign (but its magnitude is unchanged) at some point of the maneuver. We assume that aN is initially positive (i.e., that the vehicle is initially turning to the left).

Tangential acceleration (acceleration in the direction the vehicle travels) is constant and we call it aT. In the simplest case, aT is zero.

where m is the mass of the vehicle and r is the radius of curvature of the vehicle’s path. Solving for r, we get:

We see that the radius of curvature of the path is constant, so the vehicle’s path is a circular arc with the above radius.

Let us express the equations of motion as functions of time. From simple trigonometry, we know that the equations of motion are (the vehicle starts at the origin):

The vehicle is under control at all times. This means that we assume that the accelerations and speeds are small enough that the vehicle does not start to leave yaw marks and we don’t have to worry about the friction circle (see [Fricke], pp. 72-5 through 72-8).

The velocity of the vehicle at the start of the turn is v0.

The initial velocity vector is in the same direction as the positive x axis. We assume that v0 is not zero. (If v0 is zero and the tangential acceleration is zero, the path of the vehicle is a straight line, the y axis. If v0 is zero and the tangential acceleration is not zero, the equation of motion cannot be solved; see below.)

We start measuring time when the vehicle starts to turn (i.e., the time is zero when the vehicle starts to turn). We denote time by t.

where w will be determined from the initial conditions. The time derivatives of the equations of motion are:

We know that the speed of the vehicle at time 0 is v0, directed along the positive x axis. From that, we see that w = vx ⁄ r = aN ⁄ v0 . Thus, the equations of motion are:

The coordinate system is defined as follows: The origin is at the point where the vehicle starts to turn.

The x axis points in the direction the vehicle is traveling just before the turn.

The coordinate system is right handed, so that the y axis points to the vehicle’s left at the beginning of the turn.

We denote the projection of the velocity vector v on the x axis by vx and the projection of the velocity vector on the y axis by vy. Furthermore, x, y, v, vx , and vy are all functions of the time t. Finally, we use the convention that a dot over a quantity denotes the time derivative of that quantity. For example, vx is the same thing as . he simplest case: the tangential acceleration is zero It is worth noting that the assumption of a zero tangential acceleration is not realistic, but it makes the mathematics easy.

T

urns The part of the path that we’re interested in ends when y=L and we want to know how far the vehicle has traveled along the x axis. We call this x coordinate xT. From the theorem of chords, we get:

T

The time required for the vehicle to complete the turn is:

Following Newton, we note that the mass times the lateral acceleration is equal to the centrifugal force: 68 Collision

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E

vasive maneuvers Since the path is a circular arc, we again use the theorem of chords and get:

We solve this second-degree equation for yE and get

We need to discard the plus sign, since that would make for a point in the path that is after the vehicle has completed a 90-degree turn (remember that the cosine is positive until wt reaches 90 degrees).

Thus:

(note that it does not matter where along the long axis of V the center of mass of V is located) and the distance required for the passing vehicle to move from the rear end of P to the front end of P is:

Thus, we find that the minimum passing distance is:

and the minimum passing time is:

These are minima because they leave no margins for error. A prudent driver would leave some margins at the beginning and end of the passing itself, so that the passing distance and the passing time would be greater than calculated here. How much greater depends on the degree of caution exercised by the driver.

The time required to complete this turn is:

on zero tangential acceleration Deriving the equations of motion Following Newton, we note that the tangential velocity of the vehicle at time t is v0+t aT and that the mass times the lateral acceleration is equal to the centrifugal force:

N

ane change For reasons of symmetry, the path of the vehicle follows one circular arc and then another (both arcs have the same radius r and join smoothly but turn in opposite directions), switching from one arc to the other when y = L ⁄ 2. For one half of the lane change, we get, denoting by xC the x coordinate at y = L ⁄ 2:

L

Of course, for the complete lane change we have to double xC and t. assing The passing maneuver is composed of a lane change, some longitudinal travel, and a lane change back to the original lane. Let the length of the passing vehicle, V, be Lv. Let the overtaken vehicle be P, have the length LP, and be traveling with the velocity vP. (Of course, we assume that v0> vP.) Let us further assume that P stays in its lane and does not change its speed. The time required for V to move from where the front end of V has the same x coordinate as the rear end of P to where the rear end of V has the same x coordinate as the front end of P is:

P

where m is the mass of the vehicle and r is the radius of curvature of the vehicle’s path. Solving for r, we get:

We note that the radius of curvature is no longer constant, so the path followed by the vehicle is no longer a circular arc. Thus, for a lane change, we cannot use any simple symmetry arguments.

Furthermore, we note that the arc length of the path (i.e., the distance the vehicle has traveled along the path) since time zero is:

From these two quantities, we can figure out an expression for the path of the vehicle in Cartesian coordinates. From elementary differential geometry (see, e.g., [Bronshtein], p. 553), we know that:

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Collision 69

(We have used the customary notation that a dot over a quantity denotes the derivative of that quantity with respect to time.) Using the formulae for the radius of curvature and arc length, above, we get:

Dividing the first equation by vx2 + vy2 and replacing the second equation by the original form of the first equation, we get:

Solving the second equation for

and simplifying, we get:

We get:

Taking the time derivative of the first equation, we get:

Remembering that:

we can simplify the above set of equations to our almost-final set of equations:

(Note that , if v0 is 0, ) is 0 at time 0 and the time derivative of ) does not exist at time 0.) Replacing the first equation by this result, we get:

Multiplying the first equation by vy and the second equation by vx, we get:

Let us introduce the complex variable z=x+iy and express the acceleration as aT+iaN. (If you are not familiar with complex numbers and calculus in the complex plane, you can refer to, e.g., [Needham] or [Lang].) We can now express our set of equations as a single equation:

This equation1 is a first-order linear differential equation in . We know (see, e.g., [Tenenbaum], Lesson 11B, pp. 92-93) that a firstorder linear differential equation can be solved explicitly. In our case, we get (assuming that aT and v0 are not zero):

Adding the second equation to the first, we get: where c is a constant of integration. (Note that, if aT is zero, the 70 Collision

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evaluation of the integral does not yield the natural logarithm.

Note also that, if v0 is zero, the solution has an essential singularity at time zero.) Since the power function is multi-valued, we select its principal branch. We know that, at time 0, = v0, so we get:

oncluding remarks Since z is an analytic function of v0, t, aT, and aN, we can (by analytic continuation) let v0, t, aT, and aN be complex numbers and the equation of motion remains valid. A complex value of v0 will be useful for lane changes.

C T

urns and evasive maneuvers The part of the path that we’re interested in ends when y=L for a turn and when x=D for an evasive maneuver and we want to know how far the vehicle has traveled along the x or y axis, respectively, and how long it took the vehicle to get there. We need to find the intersection of the vehicle’s path with the given line. The easy way to do this is to vary the time systematically until the vehicle’s path intersects the given line. A suitable algorithm would be:

and

Integrating this equation, we get (since the vehicle is at the origin at time 0):

Set the current time to 10 seconds and the previous time to 0.

Calculate the vehicle’s position for the current time.

If the needed coordinate (y for a turn and x for an evasive maneuver) is just right (within the tolerance), we’re done.

Finding the time from a given point To find the time needed for the vehicle to get to a given point z, we need to solve the equation of motion for the time. We get:

anity check: letting one of the accelerations tend to zero Obviously, the above method for integrating the equation of motion breaks down when aT is zero, but we already know the vehicle’s path when aT is zero. Furthermore, since z is an analytic function of v0, t, aT, and aN, we expect that z converges to the circular path when aT tends to zero.

S

The final equation is the equation of motion for the circular arc that we derived earlier.

Furthermore, if we set aN to zero, we get the familiar equation for straight-line motion:

If the needed coordinate (y for a turn and x for an evasive maneuver) is too small, (the time is too small and) we set the previous time to the current time, increase the current time, and go back to step 2.

If the needed coordinate is too big we set the previous time to the current time, increase the current time, and go back to step 2. ane change The vehicle performs a turn until some to-be-determined condition is satisfied and then performs a turn in the opposite direction until it ends up traveling in its original direction but its path is offset by L from the original path. Mathematically, this means that the first path goes on for some unknown number of seconds and then the vehicle follows a path that:

L

•

Has an initial position that is the last position of the first path.

•

Has an initial velocity that is the ending velocity of the first path.

•

Has a lateral acceleration that is the first path’s lateral acceleration but with the opposite sign.

In other words the whole path at the join of the paths is a continuous function with a continuous first derivative and a step discontinuity in the second derivative.

The lane change is complete when the second path is parallel to the beginning of the first path, i.e., when the imaginary part of the derivative of the second path is zero.

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Collision 71

From experience, we know that both parts are spiral-like curves, i.e., that for the second part of the vehicle’s path, we can simply search for the first point where the imaginary part is zero.

Thus, we will use the following algorithm:

We got the following results (rounded to three decimals): Time (seconds)

Distance (feet)

Evasive maneuver, circular path

1.927

11.925

Evasive maneuver, general path

2.194

14.122

Turn, circular path

1.933

169.526

Turn, general path

1.911

173.495

Calculate the vehicle’s position along the second path for the current time and for the point at which its derivative has an imaginary part that is zero.

Lane change, circular path

2.732

240.045

2.706

248.895

If the resulting y coordinate is just right (within the tolerance), we’re done.

Lane change, general path Passing, circular paths for lane changes

9.556

840.091

Passing, general paths for lane changes

7.640

764.445

Set the travel time on the first path to 10 seconds.

If the vehicle’s position along the first path is at least as wide as the lane width, decrease the travel time on the first path and go back to the beginning of this step.

If the resulting y coordinate is too small, (the path-change time is too small and) we set the previous time to the current time, increase the current time, and go back to step 3.

If the resulting y coordinate is too big, (the path-change time is too big and) we set the previous time to the current time, decrease the current time, and go back to step 3. assing The vehicle performs a lane change, travels for some distance, and performs another lane change that brings it back to its original lane. We will need to solve two coupled lane-change problems (the straight-line travel in the passing lane is easy to handle). Given that we have already solved the lanechange problem, it is straightforward to calculate the minimum time and distance needed for the passing maneuver.

P

umerical experiments For the numerical experiments we have used an initial speed of 60 MPH, an acceleration of gravity of 32.1740485564 feet per second per second (which corresponds to the standard value of 9.80665 meters per second per second), a lateral acceleration factor of 0.2, a distance of 169 feet for the evasive maneuvers, a lane width of 12 feet for turns, lane changes, and passing, the sum of the lengths of the passing and passed vehicle is 60 feet, and several values of the tangential acceleration factor:

N •

0 for constant tangential velocity (i.e., when the vehicle moves in a circular arc) for evasive maneuvers, turns, lane changes, and passing.

•

0.1 for turns, lane changes, and passing when the vehicle does not move in a circular arc.

•

-0.3 for evasive maneuvers when the vehicle does not move in a circular arc.

72 Collision

We see that calculating the general path gives moderate but significant differences. ote: 1 As pointed out by [Bergh], this equation can be derived much more elegantly by introducing complex numbers from the start. We note that the acceleration vector of the vehicle, ( , ), can be expressed as = +i . In the complex plane, the unit tangent to the path of the vehicle is ⁄ | | . The tangential acceleration, expressed as a complex number, is aT ⁄ | | and the lateral acceleration, also expressed as a complex number, is iaN ⁄ | | . The sum of these two accelerations is the total acceleration, . Thus, we get: =( (aT+iaN))/| | We know that | |=√( ^2+ ^2 )=s’=v0+taT. By inserting this result in the above equation, we get: =( (aT+i aN ))/(v0+t at )

N

eferences [Bergh] Jöran Bergh, personal communication.

R

[Bronshtein] I. N. Bronshtein and K. A. Semendyaev, Handbook of mathematics, Van Nostrand Reinhold Company, 1985, ISBN 0-442-21171-6.

[Fricke] Lynn B. Fricke, Traffic accident reconstruction, Northwestern University Traffic Institute, 1990, ISBN 0-912642-07-6.

[Lang] Serge Lang, Complex Analysis, Fourth Edition, Springer, 1999, ISBN 0-387-98592-1.

[Needham] Tristan Needham, Visual Complex Analysis, Clarendon Press, 1997, ISBN 0-19-853446-9.

[Tenenbaum] Morris Tenenbaum and Harry Pollard: Ordinary Differential Equations, Dover Publications, 1985, ISBN 0-48664940-7.

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Vericom VC4000DAQ Performance Computer Y

Z

New tri axis 2G to 6G accelerometer up to 1000 Hz sample rate. Infinite storage time.

X

2G to 100G 1 to 1000 Hz

External accelerometers 10G to 100G.

Super easy to install and completely portable, single suction with ram mount, auto digital leveling (self leveling).

Compatible 5 Hz

♦ OBDII & CAN input. ♦ Up to 16 sensors input.. ♦ Firmware & software updates from internet. ♦ Simple calibration check.

Vehicle Rotation begins

GPS Speed

Vericom Speed

0.00

60

Angular Rate Gyro

GPS Speed

-0.10

50

-0.20

Lateral G

Vericom Distance

-0.30

Compass Heading

40 Gyro (Deg/Sec)

Acceleration (G)

(compass) built-in.

PC Communication by • USB port.

• Bluetooth up to 100 meters.

• SD Card.

• 3 RS232 ports.

• Streaming data.

GPS

0.10

N 360° magnetometer

Built-in angular rate gyro (yaw or pitch)

-0.40 -0.50

Deceleration

-0.60

Braking

-0.70 -0.80

30

CSY

20

10

-0.90 -1.00 0

1

Time (Sec.)

0

2

9

10

11

Display Average Table 2/18/2008 Date & Time 9/24/2002 09:18 AM 9/24/2002 09:19 AM 9/24/2002 09:21 AM 9/24/2002 09:22 AM 9/24/2002 09:23 AM 9/24/2002 09:25 AM 9/24/2002 09:27 AM Average of Runs

Run No. 4 5 6 7 8 9 10

Time Sec 1.95 1.95 1.95 3.46 3.41 3.35 4.13

Acceleration Average G -0.891 -0.887 -0.882 -0.897 -0.897 -0.895 -0.892

Speed MPH 38.10 37.95 37.74 68.07 67.06 65.74 80.80

Distance Feet 56.6 55.8 56.2 178.5 172.4 168.4 253.4

2.89

-0.891

56.50

134.5

12

13

14 15 Time (Sec.)

16

f 0.80

17

18

19

Range Table Speed Result 57.88

0.81 0.81 0.83

58.24 58.60 58.96

0.84 0.85 0.86 0.87 0.88

59.31 59.66 60.01 60.36 60.71

Phone 763-428-1381 USA or Canada 800-533-5547 fax 763-428-1381 info@vericomcomputers.com www.vericomcomputers.com 14320James Road - Suite 200 - Rogers, MN 55374

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Collision 73

Using Ford PCM Data to Evaluate Deceleration Rates, Brake Time and Impact Speeds

Timothy J. Reust Richard R. Ruth James M. Morgan Accident Science, Inc.

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Ruth Consulting

Accident Science, Inc

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A

I

bstract The current trend in accident reconstruction is to make use of recorded electronic event data. The accuracy of the recorded data in passenger vehicles and commercial vehicles during steady state operation has been tested and published by researchers. It has been reported previously that EDR’s under-report speed during hard braking, but to date no one has come up with a quantitative method to estimate the actual ground speed from the EDR reported speed. Well documented tests were conducted with instrumented vehicles to measure time, speed and distance. There were two distinct phases documented – the initial brake engagement phase and the post ABS engagement ongoing deceleration phase. The authors offer a method to better estimate true ground speed during each phase from the speed data reported in the EDR

nstrumentation The calibrated vehicle speed and distance were recorded using a Racelogic VBOX III GPS system. The speed recorded by the VBOX system has an accuracy of 0.063 mph averaged over four samples. The Racelogic IMU (inertial measurement unit) with the three-axis accelerometer and rate sensors was also used.

The VBOX will record digital and analog signals and was wired and programmed to record brake pedal contact, accelerator pedal position and throttle position data. Contact of the brake pedal was recorded by placing a tape switch on the surface of the brake pedal.

Accelerator pedal position and throttle position sensor information was obtained by placing wire taps onto the leads of the vehicle’s position sensors. Deceleration of the vehicle during braking was measured with the use of the IMU. The VBOX III system records data at 100 samples per second.

ntroduction Late model Ford vehicles incorporate an event data recorder in the Power Control Module (PCM) and can be downloaded using the Bosch CDR 3.1 software and appropriate cables. The PCM records data at 5 samples per second and provides speed in units of miles per hour and in 0.1 mile per hour increments. Other information recorded by the PCM includes, engine RPM, throttle percent, brake application, antilock brake activation and traction control activation. The vehicles used for this study were a 2005 Ford Crown Victoria Police Interceptor, a 2007 Ford F-150 and a 2007 Ford Mustang GT-H. The tires of the vehicles were the original equipment size and were inflated to their recommended pressures. Each of the vehicles had four wheel ABS brakes.

est Duration Consideration The VBOX system is able to record data continuously for long durations of time. The PCM for the test vehicles were known to provide a 25 second loop of data. Consideration was given to the time length of each test and the possibility of having PCM data overwritten during a test lasting longer than 25 seconds. After stopping the vehicle at the end of the test, the ignition was turned off immediately and thus preserving the last 25 seconds of the PCM test data.

I

The event data recorder is most accurate during steady state vehicle operation. The stated accuracy for GM vehicles is +/-4%, and tests on specific vehicles have consistently shown more accurate than the stated accuracy. Traditional scene evidence reconstruction, starts at point of rest, uses POR distance from POI and estimated drag factors to estimate exit velocity, applies arrival and departure angles and vehicle masses in a momentum analysis to determine speed at impact, and looks for roadway evidence of skid marks to calculate speed prior to any braking. Since more and more vehicles on the road are equipped with ABS that leave only light markings if any at all of braking, it is becoming harder to document roadway evidence of braking. Speed estimation errors compound as the analysis gets farther from know information of point of rest and point of impact. The EDR offers a direct measurement of speed prior to any braking, which is often the critical issue in criminal and civil forensic investigations.

However, since it is recommended to not rely exclusively on the EDR when other scene evidence is available, accident reconstructionists seek to compare scene evidence reconstructions to the EDR reported speed values, including speed at impact. Since many drivers perceive an impending accident and brake prior to impact, the accuracy of the EDR during braking must be documented to assist the reconstructionist in knowing how to compare the last data point recorded prior to impact to the actual ground speed at impact. The methods discussed in this paper provide a means for evaluating the vehicle speed during braking and at the time of impact.

T

D R

ata Reduction Each test produced two data sets, the VBOX instrumentation data at a rate of 100 Hz and the PCM data at a rate of 5 HZ. The two data sets were synchronized initially by matching the brake signal data and then fine-tuned using throttle data. The speed and distance data from the VBOX system was used as the calibrated set for each test.

efinement Of Brake Initiation Time The PCM brake information is recorded once every 0.2 seconds. With the 0.2 second resolution it is unknown if the brake pedal was first initiated at the beginning of the time period, in the middle of the time period or near the end. A refinement of the time period can be used to determine when the pedal was first applied and be beneficial for accident reconstruction and human factors analysis.

The vehicles that were tested for this research were brakes in a “panic stop” manner in that the brakes were applied quick and firmly.

With the synchronized test data it was possible to determine the time duration between when the brake pedal was first applied and when the PCM first reported the brake signal. Another relation of interest was the PCM reported speed decrease from the data sample just before the first brake signal (referred to as B-1) to the data sample at the first brake signal (referred to as B-0). A graph of the test data is shown in (Figure 1). The “Y” intercept value of the graph indicates that speed reduction begins approximately 0.07 seconds after brake pedal application.

An example of using this data would be if a download from a Crown Victoria showed a speed decrease of 1.5 mph from the sample just before the first brake signal (referred to as B-1) to the sample at the first brake signal (referred to as B-0). This would indicate that the

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75

brake pedal was initially applied approximately 0.14 seconds prior to the first PCM reported brake signal.

Figure 1

Sample calculation: GTH-2 test 70.0 mph, (B-1), speed just before first PCM brake “ON” 67.2 mph, (B-0), speed at first PCM brake “ON” Speed drop 70.0 – 67.2 = 2.8 mph Y = 0.0477 x (x) + 0.0698 Y = 0.0477 x (2.8) + 0.0698 Y = 0.0202 sec This indicates that the brake pedal was first applied approximately 0.202 sec before the first PCM brake “ON” data point was recorded.

D

eceleration Rate Calculation The results of the vehicles tested for this research tended to show a similar characteristic during the initial phase of braking. The PCM reported speed was underreported during initial braking engagement but the degree of underreporting became less once the ABS system began to modulate the braking. Normally the PCM data will indicate when the brake is “ON” and also when the ABS becomes “ACTIVE”.

Several methods of calculating deceleration rates from the PCM data were evaluated. The methods that were evaluated considered that the speed was underreported more severely initially after brake application and then tended to level out. The best method found was to eliminate the first two ABS active speed data points and then use the remainder of the speed data to determine the best fit line slope. The slope in miles per hour and seconds when multiplied by 0.0455 will convert to a value of “g”. This method can be used when there are enough data points available to generate the line slope, it is suggested that the fit of the points be evaluated when there are less than five remaining data points to work with.

76 Collision

S

Figure 2

ample Calculation 17.37 x 0.4555 = 0.791 g

The table of (Figure 3) shows a comparison of measured deceleration value and calculated values using the PCM data and the method discussed above.

Test

Speed

Vbox

(-2) ABS

%

Decel

Slope

Error

(mph)

(g)

(g)

F-150-1

60

0.909

0.869

-4.40

F-150-2

55

0.877

0.845

-3.65

F-150-4

50

0.877

0.817

-6.84

GTH-1

70

0.84

0.812

-3.33

GTH-2

70

0.842

0.801

-4.87

GTH-13

40

0.832

0.777

-6.61

cvspeed20

60

0.916

0.902

-1.53

cvspeed21

60

0.897

0.871

-2.90

cvspeed22

60

0.916

0.920

-0.44

Figure 3

If there are not sufficient data points to generate a reasonable slope, use the drag factor f obtained by multiple deceleration tests with a commonly used deceleration test device or by using acceptable deceleration values. While it is possible that the driver may not be braking at the maximum force, by assuming the maximum brake force the resulting calculated speed obtained at any given time will tend to be conservative which is generally preferred in law enforcement. In general, the line slope method tends to underestimate the deceleration. When using the line slope method the user needs to evaluate the result and determine if the value is reasonable and may need to decide if an actual deceleration test may be necessary.

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I

mpact Speeds In general, a significant change in the PCM speed data is an indication of an impact with another vehicle. With the 0.2 second frequency it is unknown if the impact has taken place immediately after the last data point before impact, or if it is as nearly as long as 0.2 seconds later. When the vehicle has been at a constant speed and no braking has occurred prior to the collision then the determination of impact speed may be simple. When braking has occurred leading into the collision then the impact speed determination may require extra effort. Activation of the brakes leading into a collision will cause the PCM reported speed to be underreported. The following section provides a method to evaluate the speed of the vehicle when braking has occurred either during initial engagement or after ABS modulation is taking place.

An understanding of brake activation time and deceleration buildup time can be used as a model to study the effect of the braking on the PCM speed. Shown in (Figure 4) are acceleration readings recorded during ABS brake tests. The vehicles that were tested were braked in a “panic stop” manner in that the brakes were applied quick and firmly. The accelerometer system used for the tests included a pitch rate sensor. The values shown in the graph have been refined to eliminate the effect of vehicle pitch on the accelerometer.

Time zero on the graph represents when the brake pedal is first applied. The graph shown in (Figure 5) is the average of all the tests from (Figure 4). The graph can be grouped into three distinct phases, phase “A” is the time period from brake pedal initiation to when deceleration first begins to increase, phase “B” is the time period of deceleration build-up, phase “C” is when full deceleration has been reached (Figure 6). Based on these tests, the length of phase “A” is approximately 0.07 seconds and full deceleration is typically reached at approximately 0.4 seconds after brake initiation. The time duration of phase “A” is also consistent with the findings shown in (Figure 1) with a time of approximately 0.07 seconds.

Figure 5

Figure 6

The area of phase “B” can be modeled as a triangular area where the speed loss is equal to one half the time multiplied by the acceleration (area of a triangle is equal to one half the base multiplied by the height).

To determine the speed of the vehicle during ABS braking, the following is needed.

1. The length of time from the first PCM brake “ON” (B-0) to impact.

2. The calculated time from brake initiation to (B-0).

3. The calculated effective full level deceleration time.

4. The calculated or determined deceleration rate.

5. The PCM speed at (B-0).

6. The PCM speed at (B-1), speed sample just before the first brake “ON”.

Figure 4

The effective full level deceleration time is a combination of the following: the time from brake “ON” (B-0) to impact plus brake pedal initiation to (B-0) time minus brake to begin of deceleration time minus one half the deceleration build-up time. A graphical depiction of this is shown in (Figure 7).

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Figure 7

Sample Calculation of Effective Deceleration Time:

Sample Calculation of Impact Speed where 55.1 is the speed at B-1:

This is a good method for estimating speed after initial brake engagement, assuming a maximum or panic type brake engagement.

The calculation begins with the last speed reported before braking begins and calculates the minimum speed every 0.2 seconds instead of using the actual value being reported by the PCM. Testing has shown that the PCM value is likely to be more under-reported during the initial brake engagement period.

Speed at B0 = 67.18 - (0.868 * ((.084 - .07) / .33 ) * 32.2 * (0.0+0.084 - 0.07- (.084 - .07) / 2) * 60 / 88 = 67.17 Speed at B1 = 67.18 - (0.868 * ((.284 - .07) / .33) * 32.2 * (0.2 + .084 - .07 - (0.284 - 0.07) / 2) * 60 / 88 = 65.86 Speed at B2 = 67.18 - (0.868 * 32.2 * (0.4 + .084 - .07 - (0.4 0.07) / 2) * 60 / 88 = 62.44 Note how in the first few calculations the vehicle has not reached full braking capacity and the effective braking time must be calculated for each point using the triangular area appropriate for the time since brakes were first applied. Also in the first two calculations the deceleration has not reached the upper level so an appropriate ratio is factored into the formula.

After the initial brake engagement period when ABS begins to modulate the brakes, most ABS systems are designed to control to a specified percentage of slip. For the vehicles tested, the typical slip percentage was approximately 7%. In analyzing the voluminous data, while the greatest under-reporting occurs during initial braking engagement, the authors observed some instances where even though ABS modulation had begun, that the brakes seemed to “grab” momentarily and cause a more significant underreporting.

For the data set above, brake slope f = (54.39-1.02)/2.8 = 0.868 Difference B-1 to B0 = 67.18 - 66.89 = 0.29 Time from brake to B0 = .0477 (.29) + 0.0698 = .084 sec

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Note that in the typical situation there will only be about 2 seconds of brake data before power may be lost in the crash, and the same data set presented in the last few figures would end part way through the data set as follows:

In this last case, the last EDR data point was 36.57 mph but the calculated last data point before impact would be 39.58 mph. To complete estimating a range for speed at impact, you would use the f to calculate the additional possible decel from last data point to impact of 0.868 * 0.2 * 32.2 * 60 / 88 = 3.86 mph (a range from 0 to 3.86 mph). In addition, a +/- 3mph tolerance band would have to be added.

Max speed at impact = 39.57 + 0 + 3.0 = 42.57 (Assuming Max Pedal Force) Min Speed at impact = 39.57 - 3.86 – 3.0 = 32.71 (Assuming Max Pedal Force)

In this situation the calculated f would be (54.39 - 36.56) / 21.95 / 0.8 sec = 1.02.

Because of the small number of samples available to calculate the f, and the unusually high f value obtained, let us assume you did a decel test and arrived at the same 0.868 value used in the prior set of calculations, and used that instead of 1.02. Small changes in f do not have a significant effect on the values near the start of braking – the f is more of a factor if there is prolonged braking before impact.

While calculations here have been shown to hundredths of a mile per hour for precision, recognizing the uncertainty in the assumptions, it may be more appropriate to use the nearest mile per hour.

In addition, if maximum pedal force is not used, the actual speed at impact could be higher than the high end of the range cited for when max pedal force is used.

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uture Research Future research will include vehicle tests where the braking is done at several rates that are lower than maximum.

These tests can then be evaluated to compare measured and calculated line slope deceleration rates. The test can also be evaluated for calculated impact speed methods. eferences Lawrence JM, Wilkinson CC, Heinrichs BE and Siegmund GP. “The accuracy of pre-crash speed captured by event data recorders” SAE 2003-01-0889, 2003.

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.

Reust TJ, Morgan JM. “The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and Other Factors” Collision Volume 1, Issue 1, 2006.

Reust TJ, Morgan JM. “The Accuracy of Speed Recorded by a Ford PCM and the Effects of Brake, Yaw and Other Factors” Collision Volume 3, Issue 1, 2008.

Ruth RR, Reust TJ, West O, Engle J. “Accuracy of Powertrain Control Module (PCM) Event Data Recorders” SAE 2008-010162, 2008.

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Alcohol and Vehicle Collisions - Correlation or Cause?

Peter H. Rast

r. Henry Lee once said that reconstruction was "predicting the past." He was speaking of crime scene reconstruction, but his observation applies equally well to collision reconstruction. What he meant by his observation was that crimes - and collisions - leave evidence which, when analyzed scientifically, can lead only to an opinion of a probable sequence of events that could have produced the evidence. The prediction is an opinion because the reconstructionist did not see the event in question and so can not say from direct observation what caused the observed evidence pattern. A thorough and competent analysis and reconstruction may result in a very accurate prediction, but it is still an opinion. As certain as a forensic expert may be of his conclusions, they remain opinions, models, approximations, and predictions - and could very well be wrong. The Economist notes that every model, i.e. prediction, is an approximation that makes

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simplifications and so is not a complete description - something is always left out. Business Week, speaking of financial models, points out that models are approximations and suggests that it is important to know what is left out of a model and how wrong might it be. The implication for forensics is that experts can be expected to be wrong to a greater or lesser degree because it is not possible to completely account for all aspects of an event that was not observed by the analyst. A competent, thorough analysis by a qualified and experienced forensic expert can, nevertheless, reduce “wrongness” to a minimum and present useful and meaningful conclusions.

In criminal jurisprudence generally and forensic engineering specifically, the cause of a vehicle collision is a matter of determining factual causation in terms of the sine quo non, or but for, test. This test, the proximate cause test, is defined as a cause that directly pro-

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duces an event and without which the event would not have occurred. The test is commonly stated as: but for X, Y would not have occurred. For example, had X not fired the shot, Y would not have died. In the case of motor vehicle collisions, had X not crossed over the double yellow line, he would not have collided with Y. In an alcohol involved collision, the question is whether alcohol is the cause or is alcohol a contributing factor, i.e., had X not been intoxicated, would this collision have occurred?

Researchers who have investigated the relationship between alcohol consumption and traffic collisions have done so by investigating collision frequencies and probabilities. Researchers have consistently found that as alcohol consumption and intoxication as measured by blood-alcohol content (BAC) increased, accident probability, accident risk, and accident frequency also increased. However,

while the relationships between BAC, driving ability, and collision risk are well established, researchers have not stated explicitly that alcohol causes collisions. Causality is inferred by correlating BAC to collision frequency and risk.

Courts have ruled that correlation and probability are insufficient to convict in criminal cases, requiring instead demonstration of a direct connection between an act and a criminal result. A causal relationship may be said to exist as a result of analysis of data,

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whether in the social sciences, physical sciences, or jurisprudence.

However, an identified relationship or correlation may be insufficient to reach the legal standard of proximate cause as factual cause even if such a relationship is deemed to be sufficiently strong for policy purposes or is established in statutory or case law as corpus delicti.

A cause other than the sine quo non cause may be a proximate cause if it is legally sufficient to result in liability. A cause sufficient to result in liability may be said to be a cause that produces the event or injury, even if it is one of several contributing factors.

In practice, for the law to impose responsibility, proximate cause should be limited to causes which are connected and significant to the event. Furthermore, it is reserved for the jury to determine cause in fact, which may include more than one event that may have contributed to a result. lcohol-Related Collision Investigation, Reconstruction, and Research Determination of the but for, sine quo non, cause of a collision begins with accident investigation and continues with accident reconstruction. Much has been written and taught about these subjects; accident investigation protocols and accident reconstruction methodology are well known. But, confusion arises when the correlation between BAC and collisions is confused with but for causes of collisions.

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Accident Investigation, Reconstruction, and Causation Analysis Accident reconstruction and causation analysis are inductive processes applied to collision evidence to determine how and why a collision occurred. Developing a theory of a collision begins with investigation, the process of locating, collecting, and identifying information specific to a question under consideration. Engineering and physics principles are employed to determine primary collision causes and associated factors. Rivers and Baker, among many others, have written texts specifically describing accident investigation techniques and methods. Innumerable texts and articles have been written describing applicable engineering and physics principles, forensic methodology, and legal consequences.

Daily and Shigemura published a comprehensive text describing physics and engineering principles applicable to accident reconstruction and causation analysis. They followed with a text presenting techniques and methodology specifically applicable to accident reconstruction based on physics and engineering principles. Other examples of well-regarded accident reconstruction texts include those by Fricke and Clark.

In addition to general and comprehensive accident investigation and reconstruction texts, books and articles dealing with specific and narrow accident reconstruction topics are frequently published.

Sens, Cheng, and Weichel, for example, reviewed specific literature and compiled a comprehensive treatment of perception-reaction times, a crucial factor in the analysis of right of way collisions often associated with alcohol-related collisions. This author has researched and written on topics related to low speed collisions, glass evidence, and admissibility of scientific evidence and opinion.

Risk and Causation in Alcohol-Related Traffic Collisions

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The physiological and cognitive effects of alcohol ingestion have been extensively researched and documented. The literature on the subject of alcohol’s affects on driving and other performance is also voluminous. The relevant question for forensic engineers and the judiciary is whether alcohol can be a collision cause or whether it is limited to being an associated or contributing factor. If collisions are investigated and analyzed in accordance with accepted forensic principles and methods, factually correct collision causes, primary collision factors, and any associated factors, can be properly established and the responsible driver and driving behavior identified.

With regard to driving behavior, it is well-established that alcohol affects divided attention, reaction times, night vision, judgment, vigilance, visual and spatial working memory, tracking, perception, and other factors. Researchers have consistently concluded that cognitive and motor skills deteriorate rapidly as blood-alcohol concentration increases. Although the debilitating effects of alcohol on driving behavior are well documented in the research literature and are probably within the personal experience of most adults, no study yet reviewed has stated explicitly that alcohol causes collisions. For example, Fansen et al. stated in the introduction of their paper that “...it is frequently heard that a driver after drinking often causes traffic accidents.”, however, they do not offer this statement as a conclusion after presenting their research. They conclude from their research that driving is a complex activity and that different drivers have differing capacities for alcohol and react differently after consuming alcohol.

The Grand Rapids Study investigated the correlation between BAC and collision probability. Krüger et al., Vilardo, and others re-analyzed and expanded on The Grand Rapids Study, comparing collision relative risk ratios to BAC. BAC versus collision probability studies consistently show relative collision risk increases rapidly and exponentially with increased BAC, but no identified study concluded that alcohol causes collisions.

The objective of computing relative risk ratios is to compare the probability of an event occurring when a risk factor is present at some level with the probability of the event occurring when the risk factor is not present. In the case of relative intoxication, a relative risk greater than one (1) indicates increased risk due to alcohol.

A relative risk of two (2) is interpreted as the risk of an event occurring is twice as high after consuming alcohol when compared to no alcohol consumption. Relative risk, relative probability, and odds ratio are used interchangeably, different researchers preferring one term to another.

Statistical analysis of actual collision experience was employed

by Borkenstein et al. in The Grand Rapids Study, although they considered their methodology to be survey based. Their original research was conducted in Grand Rapids, MI, in 1964, hence the popular name of the study: The Grand Rapids Study. The 1964 research was never completely published (although parts were widely disseminated), but Borkenstein et al. re-edited the research and published the results in 1974. Borkenstein and his colleagues were the first to investigate relative collision risk at various BAC levels and their work remains a model for alcohol involvement risk assessment.

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The original Grand Rapids Study was designed to identify and compare characteristics of drinking drivers and sub-groups of study participants as they were identified. The study was not designed to estimate relative collision risk, but data collected suggested such an analysis. The Study’s most noteworthy and now famous chart, Relative Probability of Causing an Accident, relates BAC levels to relative probability of collisions. The authors suggest strongly that alcohol causes traffic accidents, but do not go so far as to explicitly so state. In another chart, Percent Reduction in Total Accidents if Drivers Above a Given BAC Were Prevented From Driving, they suggest that a cause and effect relationship exists by relating accident reduction potential to elimination of drivers with specified BAC levels from the roadway.

Krüger et al. revisited The Grand Rapids Study because of a major shortcoming of that study. The Grand Rapids Study authors estimated collision risk because it was not known if the alcoholinvolved driver caused the collision in question. Using German data, Krüger et al. were able to distinguish at-fault drivers using police records and estimated DUI prevalence from survey data. The Krüger et al. results compared favorably with Grand Rapids Study results, but their relative risk curve was steeper and shifted somewhat to the left. This can be interpreted as risk increasing more rapidly than found by the Grand Rapids Study, although the two studies are consistent with regard to the general form of the risk curve.

Krüger et al. global results were distinguished by sub-groups of drinkers: moderate, heavy, and excess. As might be expected, they found differences in collision risk between the three groups. Excess drinkers had risks similar to moderate drinkers, but at higher BAC levels. The more one drinks, the more one seems to become accustomed to, i.e., be able to compensate for, or develop a tolerance for alcohol’s detrimental effects.

Krüger et al. used methods similar to Borkenstein et al., but called risk ratios odds ratios. However, Krüger et al. came closer than Grand Rapids Study researchers to explicitly stating alcohol causes accidents by using such phrases as attributed to intoxication, due to alcohol, and may be attributed to the effects of alcohol. Nevertheless, their analysis was presented in terms of odds, i.e., probabilities, so it can be said that they were suggesting, not concluding, causation although correlation clearly exists.

Levitt and Porter proposed a different and radical (their characterization) method of determining relative risk using fatal accidents as reported to the federal Fatal Accident Reporting System (FARS).

The authors presented an analysis of FARS data that correlated miles driven, which are in the trillions of vehicle-miles per year traveled (VMT), with number of fatal accidents, which are in the tens of thousands. They concluded that drinking drivers are seven times more likely to cause fatal collisions than sober drivers. Drivers with BACs above the legal limit are thirteen times more likely than sober drivers to cause fatal collisions.

Although Levitt and Porter suggested a unique method of assessing relative risk and defining externalities, they stated that their method was conservative because only fatal collisions are compiled in the FARS database and not collisions that caused only injuries or property damage. Consistent with other researchers, they did

not state that alcohol causes collisions, writing only in terms of the danger and relative risk of drinking drivers.

"relative risk studies generally concluded that doubling BAC from 0.08% to 0.16% increases the risk ratio six fold" Although relative risk studies generally concluded that doubling BAC from 0.08% to 0.16% increases the risk ratio six fold, the studies nevertheless failed to conclude explicitly that high BAC levels, or any BAC levels, cause collisions. Krüger et al. concluded, somewhat counter intuitively, that lowering presumptive BAC violation levels below the universal 0.08% level would have negligible effect on collision rates. Krüger et al. inferred that alcohol causes collisions at high levels of BAC, but they concluded the inference of causation was questionable at low levels of BAC. It may be inferred from the literature that, if alcohol causes collisions, it may not do so at all levels of BAC, for all persons, or different persons may be affected differently at the same BAC level. Borkenstein et al. reported a slight decline in relative collision risk with low levels of BAC. Garriott reported that, for a given BAC level, relative risk of collision decreases with the frequency of drinking, falling rapidly for daily drinkers as compared to infrequent drinkers. This is often referred to as the practiced drinker phenomenon. isk, Causation, and Plea Bargaining in Judicial Proceedings Statistics and Probability in Court Although risk ratios are valid statistical expressions, courts are reluctant to allow statistical evidence into criminal proceedings primarily because statistical probabilities are considered insufficient to establish the guilt or innocence of individual defendants. In People v. Collins, the California Supreme Court ruled that the probability of any two people sharing the characteristics of interest in the case says nothing about who actually committed the robbery in this case. Statistical inference, even if valid, is not a valid basis for determining guilt, absent other evidence.

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Kristen Gilbert was a nurse in a Veteran’s Administration hospital in Leeds, Massachusetts, from March, 1989 through February, 1996. In United States v. Kristen Gilbert, the 1st Circuit Court of Appeals (MA) ruled for Gilbert and said that the statistically significant evidence of increased emergencies and deaths on Gilbert’s shifts could not be admitted under Federal Rules of Evidence. The Court agreed with the trial court that such evidence was prejudicial, impressionistic, and lacked objectivity.

Rachals v. The State of Georgia reached a somewhat different conclusion, perhaps because the rules of evidence in Georgia are different from Federal Rules of Evidence. Rachals was a nurse in Albany,

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Georgia. Similar to Gilbert, patients died at a noteworthy rate when Rachals was on duty. Contrary to Collins and Gilbert, the Georgia Supreme Court admitted probability, base rate, statistical evidence. The Georgia Court ruled that statistical evidence could be admitted to show the deaths were unlikely to have occurred by chance if the data on which the probabilities were based were scientifically sound. Although the Georgia Court was reluctant to allow probability testimony because such evidence invaded the province of the jury, the jury could reject all such testimony. The Court expressed “serious reservations about mathematical computations as to the probability of guilt of an accused person”. lea Bargains and Jury Verdicts Once criminal charges are filed by prosecutors, they are disposed of by dismissal, trial, or plea bargain. Finkelstein reported that pre-trial guilty pleas in Federal District Courts in 1974 ranged from 44% to 84%, averaging 60%. Years later, Felten suggested that the vast majority of criminal cases never reach trial. Katz and Lynch wrote, in separate articles, that plea bargaining pervaded the criminal justice system. Katz and Sandefur, also separately, reported that approximately 90% of criminal cases ended in plea bargains.

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Finkelstein, Katz, Felton, Lynch, and Sandefur all suggested that plea bargaining was largely coercive in nature. Katz, Felton, and Lynch, especially, stated that there was considerable evidence that not only were plea bargains coerced, but those who failed to agree to offered pleas were punished by prosecutors who pursued enhanced criminal charges and greater punishments. Sandefur wrote that, even if plea bargains were coercive and those who did not accept plea bargains were treated more severely, neither of these outcomes were unconstitutional, unlawful, or improper. onfusing Correlation and Causation in Alcohol-Related Traffic Collisions Most research and common experience conclude that BAC and collision relative risk are significantly positively correlated. However, a well-known axiom in research and statistical analysis is that correlation is not causation. When correlation and causation are confused, one transformed into the other, for example, any conclusions that follow are suspect and questionable.

How is it, then, that when thinking of alcohol consumption and vehicle accidents, correlation has become causation in the public mind? Why does alcohol-related crash in a news report seem to imply that alcohol consumption caused the crash?

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"Why does alcoholrelated crash in a news report seem to imply that alcohol consumption caused the crash?"

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he MADD Imperative What might be the source of this correlation to causation translation? Because there is no patent empirical justification or support for the translation, the source of the confusion must lie elsewhere. Duma suggests some possibilities.

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Duma notes that drunk driving was recognized as a problem as early as 1904. Although significant anti-drunk driving efforts began in the late 1960s, serious efforts to reduced drunk driving fatalities date to the 1980s. Groups such as Mothers Against Drunk Driving (MADD), Remove Intoxicated Drivers (RID), and others began to conceptualize drunk driving as a criminal justice issue, defining drunk drivers as sinful killers” and drunk drivers as deviants. Before this period, injuries and fatalities related to drinking were considered accidents, not crimes. Recasting drunk drivers as criminals has redefined drunk drivers as a target group of deviants to which policy makers responded by legislating ever stricter deterrent-based measures as solutions to the drunk driving problem.

Duma notes that drunk driving policy and legislation can be viewed as largely morality based, having little opposition and eliciting little debate about its effectiveness. The result is technical simplicity with little review of efficacy. Because drunk driving was cast as immoral, groups such as MADD were able to project their own moral superiority and the moral inferiority of the target group, mobilize large numbers, and directly impact legislation without generating significant opposition. No supports drunk driving so laws against drunk driving will be perceived as desirable, the stricter the better. alifornia Highway Patrol Collision Investigation Manual Lack of opposition, review, and challenges to official policy regarding drinking and driving may account for investigative and judicial anomalies that have become commonplace in spite of a dearth of empirical support. A stark example of transforming correlation into causation is provided by collision investigation protocols taught to and practiced by California law enforcement officers.

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In accordance with the investigation and reporting requirements of the California Highway Patrol (CHP) Collision Investigation Manual (CIM), the factually correct but for collision cause, the Primary Collision Factor (PCF), is determined and reported in the Traffic Collision Report. Normally, CIM investigation and reporting requirements comport with accepted accident reconstruction protocol. Instructions to collision investigating officers for identifying and recording the Primary Collision Factor are contained in CHP CIM, Chapter 4, Section 9: 9. PRIMARY COLLISION FACTOR. Select the one element or driving action which, in the officer’s opinion, best describes the primary or main cause of the collision.

Whenever possible, this should be a Vehicle Code (VC) violation: a. VC Section Violated.

(1) Enter the VC or other code violation considered to be the primary cause of the collision. Include the proper subsection when applicable. Omission or error in selection of a subsection may cause the report to be rejected as an error from the SWITRS computer or the statistics may record or reflect the incorrect cause of the col-

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lision. Do not use VC Sections which do not describe the cause of collision, such as VC Sections 20001, 20002, 23103, 23104 or 23153. These violations should be charged, but are not what actually caused the collision.

The CIM also instructs investigating officers to describe the cause(s) of the collision in the narrative section of his report. Instructions for satisfying this requirement are contained in Chapter 7, Section 13, Subsection e, as follows:

cases, also by CIM mandate, the factual, sine quo non, collision cause is reported as an Associated Factor. The CIM instruction for identifying the Primary Collision Factor when the at-fault driver is determined to be under the influence of alcohol is found in Chapter 4, Section 9, Subsection a (5): (5) When the involved party, considered by the officer to be most at fault, is driving a vehicle under the influence of alcohol or drugs, the PCF shall (sic) be VC Section 23152, regardless of any other violation (running a stop sign, following too closely, excessive speed, etc.). Enter other violations under “Other Associated Factor.”

e. Cause. The officer shall include the PCF and, if applicable, any associated factors that contributed to the collision; which party was at fault; and an explanation of the items upon which the officer’s opinion is based.

Fore example, Party #1, (J. Jones), was in violation of VC Section 22450, failure to stop at a stop sign, based upon statements of parties, witnesses, and physical evidence. A party’s action or failure to act must agree with the summary and sketch.

The summary section referred to above is a subsection of the Opinions and Conclusions section of the Traffic Collision Report. Instructions for addressing this requirement are found in Chapter 7, Section 12, Subsection c (1): (1) Summary. The officer shall give his/her opinion of what took place, explain how the collision occurred, and why the collision occurred in a logical, time-sequenced manner. Each vehicle’s pre-collision, at collision, and post collision location with respect to direction of travel, highway, speed, lane, and relationship to each of the involved parties shall be addressed. The summary should also include the actions of the parties or information regarding defective vehicle equipment which contributed to the collision and how this was established and verified.

The CIM further requires that the officer include a causation subsection in the Opinions and Conclusions section of the Traffic Collision Report in accordance with instructions found in Chapter 7, Section 12, Subsection c (4): (4) Cause. The officer shall include the primary collision factor (PCF) and, if applicable, any other associated factor that contributed to the collision (which party was at fault), and an explanation of the items upon which the officer’s opinion is based. A party’s action or failure to act must agree with the summary and sketch. For example, P-2 was in violation of Vehicle Code (VC) Section 521804(a), Entry onto Highway. The cause was based on the clear line of sight which was available to P-2, frontend damage to V-1, side impact damage to V-2, 83 feet of tire friction marks from V-1, location of the AOI, and statements from the involved parties and witnesses.

However, contrary to the aforementioned instructions and good forensic practice, the CIM requires and mandates that when the atfault driver in a collision is determined to be under the influence of alcohol, an alcohol-related vehicle code violation specified by the CIM is to be identified as the Primary Collision Factor, regardless of the factual ‘but for’ collision cause. In alcohol-related collision

(a) Examples: (1) Party #1, who is under the influence of alcohol, failed to stop for a posted stop sign (VC Section 22450) and collided with Party #2 within the intersection. The PCF should indicate Party #1 for violation of VC Section 23152. “Other Associated Factor” will show Party #1 was also in violation of VC Section 22450.

Section 23152 of the Vehicle Code states, in part: “It is unlawful for any person who is under the influence of any alcoholic beverage or drug, or under the combined influence of any alcoholic beverage and drug, to drive a vehicle” (Vehicle Code). orensic Error Forensic error occurs when the CIM requires and mandates an incorrect sine quo non collision cause, alcoholrelated or otherwise, be specified as the PCF. Criminal prosecution error may follow in such circumstances when a factually correct collision cause is rejected in favor of a factually incorrect collision cause for reasons other than objective forensic analysis. Similarly, error also occurs when the factually correct collision cause is not identified as the actual cause. If, as in the Anglo-Saxon legal tradition, one enjoys a rebuttable presumption of innocence, prosecutorial error may occur when a defendant is charged with, convicted of, or pleads guilty to an incorrect criminal charge resulting from an incorrectly specified PCF. In statistical nomenclature, this is a type one error where the null hypothesis, the principle assertion, is innocence.

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onclusions It is established and accepted by competent research and common experience that alcohol adversely affects driving ability and factors affecting driving ability to a greater or lesser extent depending on BAC. It is also established that there is a statistical relationship, a correlation, between collision risk and BAC levels. Researchers have not, however, gone so far as to state that alcohol causes collisions, although inferences of a causal relationship are generally clear.

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Most courts have not allowed statistical evidence in criminal cases and so would be expected generally to disallow collision risk ratio versus BAC evidence as proof that alcohol causes collisions.

However, even if unintentional, the California Highway Patrol’s Collision Investigation Manual protocols mandate that alcohol be elevated to the but for collision cause in alcohol-related collisions when there appears to be no empirical justification for such mandate.

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With the additional consideration of plea bargaining, it is possible that criminal charges and convictions resulting from CIM mandates are relatively more severe than if CIM mandates had not been imposed. In addition, punishments resulting from application of CIM protocols may be greater than warranted by factual collision causes because plea bargaining and infrequent trials would make it less likely that inequities would be corrected. The findings in the literature strongly indicate judicial inequities.

Daily, J., Shigemura, N., & Daily, J. (2006). Fundamentals of traffic crash reconstruction. Jacksonville, FL: Institute of Police Technology and Management.

Dalrymple-Alford, J. C., Jones, R. D. & Kerr, P. A. (2003). The effects of alcohol on driving-related sensorimotor performance across four times of day. Journal of Studies on Alcohol, 64: 9397. Retrieved July 25, 2007, from http://www.highbeam.com/ doc/1G1-98079701.html

The imposition of plea bargains and the CIM mandate is particularly insidious if Felton and Lynch are correct in their assertions concerning plea bargaining. Most vehicle code violations that would be specified as Primary Collision Factors in the majority of collisions not involving alcohol are misdemeanors. Criminal charges resulting from errors mandated by the CIM in alcoholrelated collisions can be expected to be more serious than if CIM required errors had not been committed. Potential punishment for the higher charges, those which might be associated with CIM required errors, are significantly greater than for most vehicle code violations.

Dennis, M. E. (2002). Analysis and evaluation of the effects of varying blood alcohol concentrations on driving ability. American Driver and Traffic Safety Education Association, 50(4), 9-10.

Whether the CIM protocols result in systemic bias and skewing of the criminal justice system in California is unclear. Criminal procedures from arrest through arraignment, preliminary hearing, trial, and sentencing may be sufficiently extensive and diligent as to compensate for any bias introduced by the CIM’s mandate. If not, effectively transforming correlation into causation through protocols such as found in the CIM effectively subverts courts’ traditional reluctance to accept probability evidence in criminal court proceedings. However, even if the criminal justice system ultimately corrects such error in criminal prosecutions for alcohol-related collision offenses, such errors remain error and the possibility for bias and injustice in the system remains for random suspects, if not for all suspects. Because the CIM mandate is official policy and procedure, it affects all suspects initially. Whether judicial outcomes are skewed as a result is unknown, but until the question is investigated, doubt will linger in California - and perhaps in other jurisdictions, as well. eferences Aczel, A. D. & Sounderpandian, J. (2002). Complete business statistics. Boston: McGraw-Hill Irwin.

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Baker, K. S. (2001). Traffic collision investigation. Evanston, IL: Northwestern University Traffic Institute.

Borkenstein, R. F., Crowther, R. F., Shumate, R. P., Ziel, W. B. & Zylman, R. (1974). The role of the drinking driver in traffic accidents (The Grand Rapids Study). Blutalkohol, 11(Supplement 1), 1-131.

Derman, E. & Wilmott, P. (2009, January 12). Perfect models, imperfect world. Business Week, 59-60.

Clark, W. E. (1982). Traffic management and collision investigation. Englewood Cliffs, NJ: Prentice-Hall.

Daily, J. & Shigemura, N. (1997). Fundamentals of applied physics for traffic accident investigators. Jacksonville, FL: Institute of Police Technology and Management.

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Department of the California Highway Patrol. (2003). Collision investigation manual. (HPM 110.5). Sacramento, CA: Author.

Duma, T. (2006). MADD, drunk driving, and deterrence: The impact of state laws on individual attitudes and behavior. Dissertation Abstracts International, 67/01. (UMI No. 320345) Fansen, K., Jie, S. & Hsin, G. (2001). The effect of drinking on driver’s visuospatial working memory. (SAE 2001 World Congress.

No. 2001-01-0044). Warrendale, PA: Society of Automotive engineers.

Felton, E. (1993, February 15). Crime and punishment: Disorder in the court. (how pressure to enter into a plea bargain hurts those innocent of committing a crime). Insight. Retrieved November 16, 2007, from http://www.highbeam.com/doc/1G1-13462243.html Finkelstein, M. O. (1978). Quantitative methods in law. New York: Free Press.

Foster, K. R. & Huber, P. W. (1999). Judging science: scientific knowledge and the federal courts. Cambridge, MA: MIT Press.

Fricke, L. B. (1990). Traffic collision reconstruction. Evanston, IL: Northwestern University Traffic Institute.

Garner, B. A. (Ed.). (1999). Black’s law dictionary (7th ed.). St. Paul, MN: West Group.

Garriott, J. C. (Ed.). (2003). Medical-legal aspects of alcohol (4th ed.). Tucson, AZ: Lawyers and Judges Publishing, Inc. Huber, P. (1993). Galileo’s revenge. New York: Basic Books.

In plato’s cave. (2009, January 24th-30th). The Economist: Greed and fear, a special report on the future of finance. 10-14.

Jones, R. K. & Lacey, J. H. (2001). Alcohol and highway safety 2001: A review of the state of knowledge. Washington, DC 20590: National Highway Traffic Safety Administration. (NTIS No. DOT HS 809 383).

Katz, L. R. (1980). The justice imperative: An introduction to criminal justice. Cincinnati, OH: Anderson Publishing Company.

Keeton, W. P. (Ed.). (1984). Prosser and Keeton on the law of torts (5th ed.). St. Paul, MN: West Publishing Co.

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Koehler, J. J. (2001). When do courts think base rate statistics are relevant? Retrieved October 19, 2007, from The University of Texas at Austin, McCombs School of Business and School of Law website http://www.mccombs.utexas.edu/faculty/jonathan.koehler/articles/2002_Jurim.pdf

People v. Collins, 68 Cal. 2d 319, 438 P.2d 33, 66 Cal. Rptr. 497, 1968 Cal. LEXIS 167

Krüger, H. –P., Kazenwadel, J. & Vollrath, M. (2007, August 6).

Grand Rapids effects revisited: Accidents, alcohol and risk. Retrieved September 24, 2007, from http://www.druglibrary.org/ Schaffer/Misc/driving/s9p2.htm

Perkins, R. M. & Boyce, R. N. (1989). Criminal law and procedure (7th ed.). Westbury, NY: Foundation Press.

Levitt, S. D. & Porter, J. (2001). How dangerous are drinking drivers? The Journal of Political Economy, 109(6), 1198-1237. Retrieved October 22, 2007, from ABI/INFORM Global database.

(Document ID: 95456143).

Perkins, R. M. & Boyce, R. N. (1982). Criminal law (3rd ed.).

Mineola, NY: Foundation Press.

Rachals v. The State of Georgia. 184 Ga. App. 420, 361 S.E. 2d 671. (1987).

Rast, P., Stearns, R., Allison, M., Gloekler, T. & Beals, D. (2000).

Acceleration factors and maximum speeds under conditions of idle acceleration. Accident Investigation Quarterly, 1(23), 16-17.

Lynch, T. (2003, Fall). The case against plea bargaining. Regulation, 24-27.

Rast, P. H. (2006). Glass as forensic evidence. Accident Investigation Quarterly, 1(42), 33-37.

McFarland, R. A. (1969). Significant trends in human factors research on motor vehicle accidents. (13th Stapp Car Crash Conference. No. 690795). Warrendale, PA: Society of Automotive Engineers.

Rast, P. H. (2006). The Daubert decision: Accident reconstruction considerations. Forensic Examiner, 15(4), 37-41.

McLean, J. & Kloeden, C. (2002). Alcohol, traveling speed and the risk of crash involvement. Paper presented at the 16th International Conference on Alcohol, Drugs and Traffic Safety. Retrieved October 8, 2007, from http://www.saaq.gouv.qc.ca/t2002/actes/ pdf/(07a).pdf Moenssens, A. A., Starrs, J. E., Henderson, C. E. & Inbau, F. E. (1995). Scientific evidence in civil and criminal cases (4th ed.).

Westbury, NY: Foundation Press.

Moskowitz, H. (1973). Laboratory studies of the effects of alcohol on some variables related to driving. Journal of Safety Research, 5(3), 185-198.

Moskowitz, H., Burns, M., Fiorentino, D., Smiley, A. & Zador, P. (2000). Driver characteristics and impairment at various BACs. Washington, DC: U.S. Department of Transportation.

Moskowitz, H. & Fiorentino, D. (2001, April). A review of the literature on the effects of low doses of alcohol on driving-related skills. Retrieved from U.S. Department of Transportation, National Highway Traffic Safety Administration site http://www.nhtsa. dot.gov/people/injury/research/pub/Hs809028/DocPage.htm Ortman, P. (2000, Spring). The medical, legal, and social aspects of drinking and driving: annotated bibliography. Retrieved August 6, 2007, from The University of Dayton School of Law, Institute on Race, Health Care and the Law Web site: http://academic.udayton.edu/health/01status/00Ortman.htm

Rivers, R. W. (1995). Training and reference manual for traffic accident investigation. Jacksonville, FL: Institute of Police Technology and Management.

Sandefur, T. (2003, Fall). In defense of plea bargaining. Regulation, 28-31.

Sens, M. J., Cheng, P. HI., & Weichel, J. F. (1989). Perception/reaction time values for accident reconstruction. (SAE International Congress and Exposition. No. 890732). Warrendale, PA: Society of Automotive Engineers.

Spencer, B. D. (2007). Estimating the accuracy of jury verdicts.

Journal of Empirical Legal Studies, 4(2), 305-329. Abstract retrieved August 7, 2007, from http://www.blackwell-synergy.com/ doi/abs/10.1111/j.1740-1461.2007.00090.x United States v. Kristen Gilbert, 229 F. 3d 15, 55 Fed R. Evid.

Serv. 280 1st Cir. (Mass.) Oct 03, 2000.

Vehicle Code. Division 11. Rules of the Road. Chapter 12. Public Offenses. Article 2. Offenses Involving Alcohol and Drugs.

Vilardo, F. J. (1987). Relative risk of alcohol involved crashes. (SAE International Congress and Exposition. No. 870601). Warrendale, PA: Society of Automotive Engineers.

Zikmund, W. G. (2003). Business research methods (7th ed.). Mason, OH. Thomson Southwestern.

Pastore, A. L. & Maguire, K. (Eds.). (2006). Sourcebook of criminal justice statistics. Retrieved October 8, 2007, from Albany University, School of Criminal Justice from http://www.albany.edu/ sourcebook

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Forensic Photography and Crash Reconstruction Part 2: Solutions to Common Problems Robert Wyman

“This picture really doesn’t show it well, but…” f you’ve ever spoken the words, “This picture really doesn’t show it well but…,” you, too, have failed. As mentioned in Part 1, speaking these words is an admission that your image cannot be relied upon to convey the proper message to your audience.

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Does it matter?

Again, from Part 1, is your failure a detriment to your case? Will it adversely affect your other testimony points? Will the ineffectiveness of a single image result in a verdict supporting your opposition?

Let’s make sure that you never encounter such circumstances.

Proper operation of your camera takes training, just like operating your Total Station, completing your recon calculations, driving your vehicle and firing your weapon. All too often the camera is an afterthought, or perhaps approached with the belief that anyone can perform forensic photography just by aiming and pushing a button.

In Part 1, we discussed the following photo subjects which are often problematic:

• Nighttime scenes in which your images only show the reflections from license plates, roadway reflectors (RPMs) and nearby traffic signs.

• Bright, sunny scenes in which you try to record something in a shadow, but the image comes out too dark to see any details.

• Roadway surface evidence, including gouge marks and fluid spills, which appear too small in your images to be of any illustrative value.

• Recording a VIN through the windshield without seeing your own reflection in the glass.

• Illustrating a lamp filament with high magnification.

• Capturing strands of hair embedded in a windshield.

Let’s add fingerprints, seatbelt loading, crush deformation, component failures, traffic control device issues and sight distance issues to the photo discussion list, and attack each problematic

The first part of this article ran in the last issue of Collision. In that issue, the author suggested the title: "Forensic Photography and Crash Reconstruction Part 1: "The Professional Amateur Expert Witness Photographer" "this picture really doesn't show it well, but.." In the context of that article, the last portion of that title connected with the article's introduction. As a function of layout considerations, that phrase was omitted and may have made the first line in the article confusing. Collision apologizes for any confusion that omission may have caused.

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Note: the CD included with this issue of Collision contains a folder of photographs from Robert Wyman illustrating examples of photographic techniques used in this article.

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circumstance in the order listed. ight Scenes These always present the greatest challenge to a photographer, and are the greatest point of failure for amateur photographers. For the “automatic” camera crowd, night scenes exceed what the camera is programmed to do, so one should never expect a perfect image. Think of it in this manner: the camera is programmed for the majority of scenes it will encounter, and those scenes are typically in daylight and bright sun. Thus, a nighttime scene is 180-degrees opposite to the camera’s programming.

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once off “automatic” it only has a limited amount of programming to rely on. The camera doesn’t know if an image is too light or too dark for your taste (or for your accurate recording of evidence).

So, you’ll have to decide if the brightest areas are too bright and washed-out or if the darkest areas are too dark and lacking detail.

Digital imaging makes this an easy exercise, as many shots can be completed rapidly and the settings can be tweaked until they are correct.

What to do? Go “manual” instead of “automatic,” or try utilizing the pre-programmed nighttime scene modes available in some cameras. A tripod is essential for night photos, and a flash has value as well, along with other illumination strategies.

The typical problematic night shot is an expanse of black space with some pinpoints of light reflecting from license plates and traffic signs. Why does this happen? A combination of automatic settings, including short shutter speeds, in-camera light metering and illumination from a flash all contribute to the poor image. The solution is to get the camera off “automatic” mode and learn what “manual” can do for you. With longer shutter speeds and some creative lighting techniques, all the details of a scene can be rendered in an acceptable manner.

with internal flash

"One note of caution: night photos are not a “one size fits all” proposition."

One note of caution: night photos are not a “one size fits all” proposition. Segregate your photo assignment into different facets, and use equipment best suited for each subject. For example, a handheld automatic mode with flash may be fine for initial orientation views and to capture the true colors of each vehicle, plus it’s perfect for interior shots of damage, seatbelts, blood, etc.

This same setup, though, cannot be used to record the actual scene lighting provided by skylight, street lights and other sources of illumination. For an “actual light” image, within a reasonable degree of accuracy, you’ll have to use a tripod and time exposure without a flash. For each image you take, perform a critical review of the image’s brightest and darkest areas and make notes regarding whether the image is too light, too dark, or just right. This review can be done using the camera’s display screen immediately after you take the photo (if using digital). Adjust your camera settings as needed to fine-tune the exposure.

with external flash

with 3 second exposure and no flash

If your head is already spinning over this, let’s simplify the thought.

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unny Scenes with Heavy Shadows Another circumstance which confuses the typical, built-in programming of a camera is a bright, sunny scene with a dark and shadowy segment. Think of a car in a salvage yard, and your photos which start wide to encompass the entire car and end up narrow to show just the interior.

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If the camera is aimed at a bright portion of the scene, such as the vehicle’s roof or side, the bright areas will be exposed properly but the dark areas will be too dark and without detail… just another black expanse of space. This may be acceptable for the widest shots of the entire vehicle, but not for the close-up shots.

Conversely, if you aim at the dark areas of car’s interior, the entire dark area will have a significantly better exposure and much more detail; however, the exterior of the car will be too bright and washed-out.

In this scenario, break out your flash. Yes, in the daytime. Set your camera to use the flash full-time. That is, most cameras will only let the flash fire when the camera’s programming detects too little light, and that will not happen on a bright and sunny day. Delve into your camera’s menu and settings until you see how to toggle the flash “on” full-time, then fire away for all medium and close-up shots. The light emitted from the flash is not so bright as to wash out the exterior, but it’s certainly bright enough to illuminate the interior. Your images will have a more balanced exposure, meaning that few spots, if any, will be too dark or too bright on the subject vehicle. oadway Surface Evidence Gouge marks and fluid spills are often photographed too far away or too close to be meaningful. That is, a wide-angle shot of the area-of-impact may illustrate gouges in relation to other evidence, but they are typically too small to be recognized by a viewer of the photo unless specifically pointed out. Realizing this, the photographer usually completes a second photo, this time standing almost directly over the gouge, and filling the frame with nothing but the gouge.

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The problem? Individual gouges cannot be identified, nor can the gouge length and direction be determined by the close-up photos alone. To remedy this, one only has to add some tools to the closeup images of gouges and fluid spills. Plastic evidence markers, a surveyor’s compass, and a small GPS can be used individually or in combination to fully document each point of roadway evidence.

The depth of a gouge, if important, can be modeled with a carpenter’s contour gauge or measured directly with a laser.

As for the GPS, don’t sweat the “accuracy” issue. We’re not building the road, we’re just trying to show that a particular gouge or fluid spill is in fact part of this scene at this intersection. A consumer GPS is more than adequate for the task.

IN Plates VIN Plate photography through a curved windshield calls for a polarizing filter. In many VIN photographs, the number is barely visible through on-glass reflections of the sun, sky, clouds, trees, buildings or even the photographer themselves.

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Utilization of a polarizer will reduce and often eliminate the surface reflections, leaving the VIN more visible to the camera. If reflections remain problematic, a compact black umbrella… just a small rain umbrella… can be held low near the windshield to mask the sky, clouds and other visual elements. The back (non-reflective) side of a photo reflector panel may also be held and angled to best mask a problem reflection in the glass. amp Filaments If you have the luxury of extracting components and working with them in a lab environment, filaments can be imaged with just a simple setup that provides support, illumination and a measurement scale for the bulb’s base and/or envelope.

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In the field, however, a damaged vehicular lamp can be in any state of destruction and may be facing in any direction. Crushed sheetmetal which obstructs access to the lamp and/or sharp components which make close-quarters photography a hazard may further compound the assignment.

For this task, I prefer a small point-andshoot (digital) camera with top-rated macro capabilities. Don’t look to the camera manufacturers for this information, however. Instead, read the reviews on photo websites to see which cameras provide the best macro performance and smallest close-focusing distance.

Using a small camera and a safetygloved hand, I can usually reach in and around most obstacles to get a macro photo of a filament without having the need to look into a larger camera’s viewfinder or maneuver a larger camera’s body and lens through the sheetmetal maze. For photographers who wish to

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guard against scratches and damage to the camera in this environment, a lightweight hard-plastic or soft-vinyl waterproof camera case/sleeve works perfectly. air Strands in a Windshield As with lamp filaments, hair strands are perfect subjects for macro photography. Experimentation with direct lighting, reflected lighting (using a mirror, white card, or photo reflector panel) and back-lighting (through the windshield) are recommended prior to taking the “final” documentation series of images. Of primary interest in hair strand documentation is the strand itself, not the spiderweb of shattered glass around it. The glass pattern can be photographed separately and without an extreme close-up or macro shot.

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standard flash photo

To optically separate the strand from the nearby (and often confusing) array of lines from the shattered glass, the strand is kept in sharp focus and a shallow depth-of-field is used, via the Aperture control mentioned previously. ingerprints I’m seeing a convergence in the disciplines of Crash Reconstruction and the more classic forms of Forensic Science. Traffic Homicide Investigators are starting to talk to Crime Scene Technicians, and the tools and techniques are beginning to merge or even overlap.

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A few “Crime Lab” assignments have always had a natural linkage to crash recon, such as the documentation of tire tread patterns and perhaps shoe prints on brake pedals. But, the “CSI Factor” has definitely made its mark on the recon world, both in the public and private sectors.

Some recon practitioners are looking into using Alternative Light Source (ALS) photography, including ultraviolet and infrared, to produce images of occupant biological evidence beyond what can be seen with the naked eye. Liquid chemical sprays, gases and powdered materials are also being used to better expose biological residues. In fact, traffic homicides as well as less-severe crashes are often being treated with the same reverence as a crime scene, instead of the more typical “it’s just another crash” mentality and the accompanying “evidence eradication” procedures.

Fingerprint documentation has emerged as a relatively new task for reconstructionists. Whether on a steering wheel, gearshift handle, headlight switch, radio knob, ignition key or door, fingerprints are being requested in all manner of cases to identify occupant positions and verify the use or non-use of safety equipment.

If formal documentation by criminologists is unavailable, nondestructive photographs can often be completed with just a little patience, some creative lighting, and perhaps some colored filters (either physical filters attached to a lens or electronic filters applied via post-processing software). Excellent fingerprint images can usually be obtained from smooth knobs and flat panels, and surprisingly good images are often obtained from textured and irregular surfaces, all with just a macro lens, various lamps, and (optionally) the aforementioned filters.

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strong sidelight flash

eatbelt Loading Macro photography is an excellent tool for seatbelt issues.

Loading may generate d-ring damage from light abrasions to melted plastic, plus webbing which may be stretched, abraded or torn. Biological evidence may also be present in the webbing and suitable for macro, microscopic and Alternative Light Source (ALS) photography.

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rush Deformation Overall images of severe crush deformation require little thought, and represent the staple of most vehicle inspection documentation. But what of the more subtle impacts and low-speed collisions? What about adding poor lighting and light-color vehicles to the mix? Photographing a shallow indentation on a white vehicle in the shade is particularly daunting.

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For such assignments, I use a visualization technique that models the crush to provide a visual reference and measurable documentation effort. The large contour gauge, mentioned previously, allows either 12” or 24” long contour models. This technique is also useful for modeling pedestrian-impact indentations to hoods and quarterpanels, as well as any other issue where the shape of an item is important. omponent Failures Once again, macro photography is the proper tool. Solid objects in close quarters present their own unique challenges for lighting, measurements and photo accuracy. The

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key is to practice on such small subjects, at the comfort of your desk, so you’ll be proficient once a field-assignment materializes.

sociations such as AASHTO. For those unfamiliar, many local Codes can be freely obtained at www.municode.com. Select “online library” and then select your state from the map. A text-link listing will appear with all online jurisdictions such as counties and municipalities. Next, do a keyword search for “sight triangle” or similar phrase, and any Code with that keyword will be immediately displayed.

The next need to fulfill is that of photography and visualization. I want to show a jury what could have been seen barring any other circumstances. Now, I don’t want my Human Factors friends to get up in arms, because I’m not saying this is exactly what a driver actually saw prior to a crash; I’m only saying that ‘n’ distance was available to the driver for a clear view in that specific direction.

I use a 50mm equivalent lens to best simulate the normal magnification and horizontal visual field of human binocular vision, and a visible laser to pinpoint the line-of-sight dimension.

raffic Control Device Issues Documentation of traffic control devices (traffic signals, signs and roadway pavement markings) are fairly straightforward, but sometimes a circumstance is so unique that special documentation is needed before the situation changes. My only advice is to get the shot and don’t procrastinate. Personal safety is always #1 of course, but get the shot now because it probably will not be available later.

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onclusion Avoiding the admission "this picture doesn't really show it well but..." is not all that though when you know a little more about your camera, equipment, and how to use it more efficiently and effectively. Hopefully, this series of highlighted points will help make you photos just that: more effective.

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Photo Exhibit “K” illustrates a traffic signal malfunction during one of South Florida’s particularly heavy summer thunderstorms with horizontal rain… and it wasn’t even a hurricane!

ight Distance Issues In my practice, the documentation of sight distance fulfils two distinct needs. First, I want to obtain a “down range” measurement for use on a CAD diagram or scaled aerial photograph. This allows for the construction of a “sight triangle” which may be compared to a variety of local Codes and Ordinances, plus industry standards and recommended practices published by national as-

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Book Reviews Joseph E. Badger

bout the reviewer:

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Joseph E. Badger, retired state police officer and internationally known crash reconstructionist, has reviewed and evaluated accident reconstruction computer programs and books for nearly two decades. Author of the book Trailer Underride: Conspicuity, Human Factors and Rear Bumpers (IPTM, 1998), Mr. Badger has written over one hundred articles published in such periodicals as the Accident Reconstruction Journal, Accident Investigation Quarterly, Law & Order magazine, and Police & Security News.

Forensic Aspects of Driver Perception and Response, Second Edition, by Paul Olson and Eugene Farber At a recent deposition, one of the five attorneys sitting at the table asked me about the speed a driver could go before overdriving his headlights. I opined at the time that once you get over 30 mph you were probably overdriving your headlights and that got the lawyers all excited.

Naturally, they wanted me to say that someone driving 50 mph was therefore being unreasonable.

Let’s turn to page 157 in a book titled Forensic Aspects of Driver Perception and Response, Second Edition, by Paul Olson and Eugene Farber: “The expression ‘overdriving one’s headlamps’ can be taken to imply that the driver is operating at such a speed as to be unable to cope with any hazard that may happen to be in the roadway.

That is hardly the case. … For some types of targets and driving conditions, the fact is that we begin to ‘overdrive’ our headlamps almost from the moment the car starts to move forward.”

On another matter, Chapter Six, “Judgments of Speed and Distance,” delves into perception of distance and speed. On one particular point, the authors write: “Judging distance to a vehicle 94 Collision

ahead traveling in the same direction at night presents a somewhat more difficult problem. On unlit roads the primary vehicle size cue is the separation of the rear signal lamps. In fact, until the overtaking driver is within headlamp range, tail lamp separation is likely to be the only cue. On cars the separation of the outermost edges of the lamps is on the order of five feet (1.52 m). On semitrailers the distance is around eight feet (2.44 m).

“This variability of tail lamp separation can be a problem for drivers.” And the authors explain why.

Regarding perception-reaction time (PRT), the figure 1.5 seconds has been bandied about for decades and one wonders how that got started. In their chapter on driver perception-response, Olson and Farber state “There is considerable variability, with perceptionresponse times at the 85th percentile ranging from 1.26 seconds to 3.60 seconds.”

I’ve been queried occasional by attorneys, “What’s the standard perception/reaction time?” (They may replace “standard” with “average.”) My answer, while it may sound wishy-washy, is “It depends.”

I posed the question to Paul Olson. His answer is a bit more comprehensive. “If I'm asked what is a "typical" PRT, I usually say there is no such thing. It depends on a number of things.

The investigator has to think through the situation that the driver faced, then try to estimate the PRT based on his/her knowledge of the relevant research.”

Other areas in the book that caught my eye upon first reading and hopefully will interest the accident reconstructionist include the

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chapters covering human factors, driver expectation, conspicuity, problems in the use of nighttime photography as evidence in litigation, and, as they say, the list goes on.

I asked Dr. Olson how and when he got into the field of driver perception/reaction in the first place. He said, “My first introduction to lighting issues came while evaluating lighting and signaling systems that GM had under development at the time.

In 1971, I moved to the University of Michigan Transportation Research Institute (UMTRI). Work had been under way there on lighting problems prior to my arrival and I continued that while I was there. Over the years we carried out a number of studies of headlighting, signal lighting, visibility and legibility of highway signs, and conspicuity treatments for large trucks. At one point NHTSA wanted to put together a book that ended up being called the Driver Performance Data Book. I was given the job of preparing the chapter on perception-response time. That got me into that area.”

The book covers principles of vision and perception, visibility, evaluation methods, and complicating factors.

For those readers who may already have the First Edition, additional chapters have been added to this Second Edition that cover some of the same topics but in greater detail and depth. Newly added chapters present entirely new material on such subjects as driver eye movements and visual attention.

Again, the 6 x 9, 372-page casebound book is Forensic Aspects of Driver Perception and Response, Second Edition, by Paul Olson and Eugene Farber. Published by Lawyers & Judges Publishing Co., Inc. Available through their website www.lawyersandjudges. com.

Speaking of Paul Olson, he has spent decades involved with human factors since receiving his Ph.D. in industrial psychology in 1959.

He has co-authored or contributed to a number of books other than the one mentioned above. Among the newest is a 2007 tome titled Human Factors in Traffic Safety, Second Edition. A tome, just so you’ll know, is defined as “a book, especially a large or scholarly one” (The American Heritage® Dictionary of the English Language, Fourth Edition, Copyright © 2006 by Houghton Mifflin Company).

I mention that because this book is indeed large and scholarly. Its 533, 8.5 x 11 pages weigh four pounds! That’s 1.81 kilograms!

Doctors Olson and Robert Dewar are the co-authors; however, additional contributors include Jeff Caird, Gerson Alexander, Paul Green, Ralph Haber, Lyn Haber, Peter Hancock, Fred Hanscom, Alan Hopewell, Michael Janoff, Herbert Moskowitz, Alison Smiley, and Sue McNeil.

The human factors contributors’ backgrounds range from psychology to kinesiology (the science dealing with the interrelationship of the physiological processes and anatomy of the human body with respect to movement) to psychopharmacology (dealing with the psychological effects of drugs) to ergonomics (the applied science of equipment design, as for the workplace, intended to maximize productivity by reducing operator fatigue and discomfort). They

have written scores of books, papers, treatises, etc.

Brief bios of each may be found at www.lawyersandjudges.com. In the search box enter Human Factors in Traffic Safety and read all about the contributors. You can also click on “Table of Contents” to get an idea of the topics addressed; however, let me give you some detailed observations.

For example, in one of Paul Olson’s chapters he lists nine statements about human memory, such as “An eyewitness report is accurate evidence as to who was present and what happened” and “Your memory is stable over time.” After you finish laughing, read further how all the studies and all the experts give strong evidence “demonstrating that each of those statements is contradicted by the facts.”

We know that driving involves three main fundamentals: the vehicle, the environment, and the driver.

Of those three elements, driver behavior is usually the most complex but least understood. That’s where this book comes in handy. Many chapters offer many insights into the realm of driver expectancy.

Paul Green writes in his chapter “Where Do Drivers Look While Driving (and for How Long)?” that it “does not take a rocket scientist, or even a human factors expert, to realize that driving is a task that depends on visual input.” Many of my associates ask how long particular tasks take (turning the head, looking at the dash board, &c.). Unfortunately, the answer is often “It depends.” This chapter helps explain why that is.

Green notes that “the value obtained may depend upon the decision criteria used by drivers such as (1) limiting the probability of a crash, (2) limiting the probability of a lane departure, or (3) achieving some subjective level of comfort/discomfort for the driving situation while looking away.”

Alison Smiley’s chapter “Fatigue and Driving” has a section titled “Arousal and performance.” That is probably not what you’re thinking. She delves into physiological causes of fatigue, crash risks, and countermeasures to sleepiness.

In one of Robert Dewar’s chapters, “Age Differences – Drivers Old and Young,” he lists some of the limitations of older drivers’ abilities that have received the most attention by the traffic safety community. Foremost are failing sensory and information processing capacity.

Dewar then goes into ocular changes, contrast sensitivity, visual acuity, memory, stress, and more.

One of my favorite topics regarding human factors and the driving experience is cell phone usage. Chapter 10, “Driver Distraction”

by Dewar and Jeff Caird, covers many facets of distraction, chief among them is driver performance while using cell phones, both hands-free and handheld.

The authors state: “Cell phone use while driving research predominates in the distraction literature.”

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They explain, “Using a cell phone increases a driver’s capability to respond by about a quarter-second [and] answering, dialing and conversing all affect performance, but for different reasons.

Answering and dialing remove the eyes from the road causing missed events and slowed response, whereas talking withdraws attention from the roadway.”

They go on to describe why cell phone use is so much different than talking with passengers, roadside advertising, radio, CD, MP3 players, and other distractions.

In discussing cell phone usage while driving, Alan Hopewell’s chapter “Neuropsychological, Medical and Psychiatric Disorders and Motor Vehicle Operations,” says, “Although also not a formal ‘psychiatric disorder,’ the use of cellphones, like road rage, has become a cultural trend in its own right which undoubtedly affects the accident rate of the nation.” He goes on to describe the problem.

read, he answered, “That’s a tough one to answer. It will depend on the problem areas facing the individual at a given time. In my experience (which may be biased by the type of problems I'm called upon to testify about), many reconstructionists testify about night visibility and PRT with some frequency. Thus they should be very familiar with those areas as covered in both books.”

Human Factors in Traffic Safety, Second Edition by Dewar and Olson, et al, (2007), is available through the publisher’s website www.lawyersandjudges.com. You may contact L&J by phone (800-209-7190), by fax (800-330-8795), or by e-mail (sales@ lawyersandjudges.com). You can write the old-fashioned way and reach them at P.O. Box 30040, Tucson, AZ 85751. Alternatively, you can drive over for a visit at 917 North Swan Road, Suite 300, Tucson, Arizona. Tell publisher Steve Weintraub I said hello.

The book includes chapters on alcohol and drugs (I prefer “alcohol and other drugs”), driver education, vehicle and roadway design, visibility with motor vehicle headlamps and under roadway lighting, traffic control devices, environmental factors, railroad grade crossing accidents, highway work zones, and much more.

When I asked Olson of the two books, which chapters does he consider the most important for accident reconstructionists to

Commercial Vehicle Accident Reconstruction and Investigation, by Roy Sutphen and Rick W. Varner

Back in the day, okay so it was only 2001, Varner asked me to give a presentation on Trailer Underride at a conference put on by the Pennsylvania Traffic Institute for Police Services (TIPS) at the fantastic Seven Springs Conference Center.

In 1973, Rick Varner worked in law enforcement in Cambria County, Pennsylvania. Nearly a decade later he joined forces with TIPS, which grew over the years to become the Institute for Law Enforcement Education (ILEE).

Having written Trailer Underride: Conspicuity, Human Factors and Rear Bumpers, (Institute for Police Technology & Management, Jacksonville, 1998), I thought I had seen the results of just about every type of trailer underride crash on the books. That is, until I saw the photo on page 257 of the Varner/Sutphen book. I’ve seen cars that were fairly well flattened after having passed beneath a semitrailer, but their photo wins the prize, hands down.

Over the years, Rick conducted commercial vehicle (heavy trucks) crash tests.

In fact, I consider their nine-page chapter “Trailer Underride and Rear-End Protection” one of those “must-read” sections of any book.

With that background, Varner teamed up with Roy Sutphen, Sr. and the two of them wrote Commercial Vehicle Accident Reconstruction and Investigation, published by Lawyers & Judges Publishing Co. Inc. of Tucson, AZ.

But the book isn’t about only trailer underride. There are chapters covering Roadway Evidence, Vehicle Evidence, Human Factors, Off-Tracking, Vehicle Dynamics, Commercial Vehicle Rollover and Onboard Computers.

Sutphen retired after 25 years with the Pennsylvania State Police.

He was a motor carrier inspector and had accident reconstruction training. Sutphen eventually became a member of ILEE’s adjunct staff.

96 Collision

Chapter 15, The Brake System, discusses Hydraulic Brakes Systems and Surges, Electric Brakes, Air Brake Components, Air Over Hydraulic Brakes, Truck Retarders and Wedge Brakes.

For those just getting into commercial vehicle accident reconstruction, there are primer chapters on such topics as Out-ofService Criteria, Types of Carriers, Driver Responsibilities, Driver's

www.collisionpublishing.com

Record of Duty Status, Commercial Driver's License Regulations.

The book discusses various vehicle components such as the electrical system, wheels, rims and tires, plus many more too numerous to mention.

Besides 392 pages (including the index) containing valuable text, there are over 100 photographs of everything from a pop-off valve and moisture ejector to graphics demonstrating how to calculate off-tracking and weight shift to showing the difference between a Dayton wheel and a Budd wheel.

Page 291 even shows Rick after getting his hands dirty.

What we have here is three books in one. “Book 1” (my divisions, not Varner’s), including chapters one through six, covers licensing, log books, types of carriers, out-of-service criteria, and such.

“Book 2” (chapters seven through 15) describes commercial vehicle components and systems. “Book 3” (chapters 16 through 29) is what I call the meat of the text. This section covers vehicle and roadway evidence, human factors, vehicle dynamics, onboard computers etc.

The final chapter, titled “Other Speed Equations” discusses a few of the formulae that many accident reconstructionists know about but are the less memorized ones. Such as the commercial vehicle hydroplane formula and determining speed when you know gear positions and the truck’s RPM at the time of the collision.

Then there’s that dreadful weight shift equation that is so beastly that I doubt you’ll ever really use it.

However, it’s nice to know where to find it – just in case.

You may get the book through Lawyers & Judges Publishing by going to their website http://www.lawyersandjudges.com/ and enter “Varner” (without the quotes) in the Search box and click on By Author.

Or call L&J toll-free at (800) 209-7109. Or you may ask questions via e-mail at sales@lawyersandjudges.com.

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Collision 97

Index of Articles Collision Vol.1, Issue 1 to Vol. 3 Issue 2 www.collisionpublishing.com Accelerometers

Hydroplaning: The Effect of Water on the Roadway: Volume 3, Issue 2, Page 78

Effects of Sample Rates on Accelerometer Based Skid Testing and Unit Comparison: Volume 2, Issue 2, Pg 66 Quantifying the Aerodynamic Forces Acting on Objects during a fall: Volume 3, Issue 1, Page 14 Basic Integral Calculus For Crash Reconstruction: Volume 3, Issue 2, Page 56

ACM (Airbag Control Module)

A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53 Two-Dimensional Analyses of EDR In-Formation: Volume 2, Issue 1, Page 12 Cable options for the “CDR System Handyman”: Volume 3, Issue 1, Page 82

Busses

Compartmentalization Compromised: The Issue of School Bus Passenger Safety: Volume 2, Issue 1, Page 28 School Bus Rollovers and Passenger Compartment Ejection: Solving the Puzzle Using Videoanlytics: Volume 3, Issue 2, Page 66 Bus Braking Tests: With and Without ABS: Volume 3, Issue 2, Page 70

Case Problems

Crash Data Case Study: Volume 1, Issue 1, Page 28 (Solution on page 97) Crash Data Case Study (Follow-up from Issue 1): Volume 1, Issue 2, page 40

Aerodynamics

Quantifying the Aerodynamic Forces Acting on a Vehicle and Projectile: Volume 2, Issue 2, Page 120

Book reviews

2 in 3 out Case Study: Volume 1, Issue 2, Page 90 (Solution on page 102) Two Crash Data Case Problems: Volume 2, Issue 1, Page 24 (Solution on page 61)

Book Reviews: Volume 2, Issue 1, Page 82 Book Reviews: Volume 3, Issue 1, Page 60

Secondary Contact Case Problem: Volume 2, Issue 2, Page 58 (Solution on page 150)

Braking

The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and other Factors: Volume 1, Issue 1, page 9 Deceleration Rates of Modern Passenger Vehicles During Straight Line Braking and Yaw Events: Volume 1, Issue 2, Page 20 Identification of Unusual Tire Marks at the Scene of a Motor Vehicle Collision: Volume 1, Issue 2, Page 30 Application of Drag Coefficients to ABS Related Sideslip: Volume 2, Issue 2, Page 46

Commercial vehicles

Contribution of a Laterally Displaced Vehicle to the Post-Impact Deceleration of a Heavy Truck: Volume 1, Issue 2, Page 96

Crash Testing

Carrying out a High Speed Crash Test for the Dutch Police: Volume 2, Issue 1, Page 52 The Accuracy of General Motors Event Data Recorders in NHTSA Crash Tests: Volume 2, Issue 1, Page 70 ARC-CSI Crash Conference – Crash Test Data Summary: Volume 2, Issue 2, Page 6

Effects of Sample Rates on Accelerometer Based Skid Testing and Unit Comparison: Volume 2, Issue 2, Pg 66

Effects of Sample Rates on Accelerometer Based Skid Testing and Unit Comparison: Volume 2, Issue 2, Pg 66

Bus Braking Tests: With and Without ABS: Volume 3, Issue 2, Page 70 98 Collision

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Validating Speed Analysis Calculations with Crash Test Data: Volume 2, Issue 2, Page 70 European Accident Reconstruction by the Visual Comparison with Crash Tests: Volume 2, Issue 2, Pg 92

Crush

Getting Published

Getting Into Print as an Accident Reconstructionist: Volume 1, Issue 2, Page 56

GM

Implications of Symmetric Sine-Based Collision Pulse Models on Force-Deflection Characteristics: Volume 2, Issue 2, Page 104

Analysis of the GM Sensing and Diagnostic Module in 260 Degree Linear Momentum Collisions: Volume 1, Issue 1, Page 17

An Alternative Formulation for Symmetric Sine Based Collision Pulse Models: Volume 3, Issue 1, Page 34

A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53 The Accuracy of General Motors Event Data Recorders in NHTSA Crash Tests: Volume 2, Issue 1, Page 70

Damage-Based Collision Severity Reconstruction Technique: Volume 2, Issue 1, Page 34

General Motors Data Recording: A Visual Approach to the Logic Functions: Volume 2, Issue 2, Page 18

When Measuring Vehicle Crush… Find the Method that Works Best for You: Volume 2, Issue 2, Page 78

Average Daily Ignition Cycles in SDM Equipped, GM Vehicle: Volume 2, Issue 2, Page 42

Vehicle Crush Measurement: Helpful for extracting Key Details of Crash Scenes: Volume 2, Issue 2, Page 98 Implications of Symmetric Sine-Based Collision Pulse Models on Force-Deflection Characteristics: Volume 2, Issue 2, Page 104 An Alternative Formulation for Symmetric Sine Based Collision Pulse Models: Volume 3, Issue 1, Page 34 Single Point Crush Variation: Volume 3, Issue 1, Page 94

EDR Durability

EDR Durability: Volume 2, Issue 1, Page 64 Vehicle Fires and Airbag Modules: Volume 3, Issue 1, Page 18 Getting Data from Destroyed SDMs: Transferring EEPROMs Between Modules: Volume 3, Issue 1, Page 28

Ford

A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53 Dynamic Accuracy of Powertrain Control Module (PCM) Event Data Recorders During ABS Braking: Volume 3, Issue 1, Page 44 The Accuracy of Speed Recorded by a Ford PCM and the Effects of Brake, Yaw and other Factors: Volume 3, Issue 1, Page 48 Comparing Different Sources of CDR Data to “Real World” Crashes: Volume 3, Issue 1, Page 88

Comparing Different Sources of CDR Data to “Real World” Crashes: Volume 3, Issue 1, Page 88

GPS

The Future of Accident Reconstruction: Volume 2, Issue 1, Page 62 Using GPS Based Data Acquisition in Forensic Accident Reconstruction: Volume 2, Issue 2, Page 114

Ignition Cycles

Average Daily Ignition Cycles in SDM Equipped, GM Vehicle: Volume 2, Issue 2, Page 42

Legal Issues

CDR Presentation and Validation in Legal Proceedings: Volume 1, Issue 1, Page 43 Rational Legislative and Organizational Policy for Automotive Event Data Recorders: Volume 1, Issue 1, Page 56

Momentum

Analysis of the GM Sensing and Diagnostic Module in 260 Degree Linear Momentum Collisions: Volume 1, Issue 1, Page 17 2 in 3 out Case Study: Volume 1, Issue 2, Page 90 (Solution on page 102) Analysis of Collisions: Point Mass Mechanics and Planar Impact Mechanics: Volume 2, Issue 1, Page 38 Use of the Combined Velocity Equation in Cases Involving Post-Collision Movement: Volume 2, Issue 2, Page 52

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Collision 99

Reconstruction & Analysis of Steering-Induced, OnRoad, Un-tripped SUV Rollovers (Part 2): Volume 2, Issue 2, Page 124

Centrifugal Force: Is It Real?: Volume 3, Issue 2, Page 48

Motorcycles

Motorcycle Crash Investigation: Volume 1, Issue 2, Page 32

PCM

SDM

Dynamic Accuracy of Power train Control Module (PCM) Event Data Recorders during ABS Braking: Volume 3, Issue 1, Page 44

Two-Dimensional Analyses of EDR In-Formation: Volume 2, Issue 1, Page 12

The Accuracy of Speed Recorded by a Ford PCM and the Effects of Brake, Yaw and other Factors: Volume 3, Issue 1, Page 48

Detailed Comparison of Vehicle Speed and the Speed Recorded by an SDM, Volume 2, Issue 2, Page 32 Average Daily Ignition Cycles in SDM Equipped, GM Vehicle: Volume 2, Issue 2, Page 42

PDOF

PDOF: Principal Direction of Force: Volume 1, Issue 2, Page 12

Getting Data from Destroyed SDMs: Transferring EEPROMs Between Modules: Volume 3, Issue 1, Page 28

Pedestrians

Night Time Pedestrian Collision Reconstruction Factors: Volume 2, Issue 2, Page 82

Photography

Pictometry in Crash Investigation: Volume 1, Issue 2, Page 44

Cable options for the “CDR System Handyman”: Volume 3, Issue 1, Page 82

Simulations

Simulations 101: Anatomy of a Simulation: Volume 1, Issue 2, Page 36

Making History: PhotoModeler Software Helps Knott Laboratory Reverse-Engineer the Past: Volume 1, Issue 2, Page 50

Making History: PhotoModeler Software Helps Knott Laboratory Reverse-Engineer the Past: Volume 1, Issue 2, Page 50

Close Range Photogrammetry: Volume 2, Issue 1, Page 20

Snowmobiles

Close Range Photogrammetry as a Routine Crash Reconstruction Tool Within the Florida Highway Patrol: Volume 3, Issue 2, Page 16

Speed

Snowmobile Data: Volume 2, Issue 2, Page 74

Forensic Photography and Crash Reconstruction, Part I: The Professional Amateur Expert Witness Photographer: Volume 3, Issue 2, Page 62

RCM

The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and other Factors: Volume 1, Issue 1, Page 9

A Review of Various ACM Module Types and Data Recorded: Volume 1, Issue 1, Page 53

Vehicle Speed Sensor Calibration: Volume 3, Issue 2, Page 22

Tire marks

Identification of Unusual Tire Marks at the Scene of a Motor Vehicle Collision: Volume 1, Issue 2, Page 30

Visibility

Night Time Pedestrian Collision Reconstruction Factors: Volume 2, Issue 2, Page 82

Rollovers

Vehicle Dynamic Characteristics of SUVs in On-Road, Un-tripped Rollover Accidents: Volume 1, Issue 2, Page 62 Reconstruction & Analysis of Steering-Induced, OnRoad, Un-tripped SUV Rollovers (Part 1): Volume 2, Issue 1, Page 88

100 Collision

Yaw

The Accuracy of Speed Recorded by an SDM and the Effects of Brake, Yaw and other Factors: Volume 1, Issue 1, Page 9 Deceleration Rates of Modern Passenger Vehicles During Straight Line Braking and Yaw Events: Volume 1, Issue 2, Page 20

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BOSCH CDR 3.2 Software

• Added roll angle data to CDR reports for the following vehicles (if equipped):

CDR System v3.2 Release Info CDR Version 3.2 is a “Software Only” release.

There will be no new hardware required to support the added software capabilities. Below lists the new and exciting software changes made to the CDR product for version 3.2.

General changes to the CDR System In general, there were many improvements to the CDR software application including but not limited to: • Added "_ACM" as part of the default CDR file name when saving EDR data from airbag control module • Changed "KPH" units of measurement label to "km/h" • Added support for CDR "double click" file opening when the CDR application is already running • Many changes to the CDR application help file

New Chrysler Coverage Below lists the new Chrysler vehicle coverage for airbag control module (ACM) crash data retrieval.

For details on total coverage, refer to the Supported Chrysler Vehicles section of the CDR help file.

• 2008 Dodge Magnum • 2008 - 2009 Chrysler 300, Town & Country; Dodge Caravan, Challenger, Charger, Dakota; Jeep Commander, Grand Cherokee, • 2009 Journey • Added DLC download capability for 2008 2009 minivans and Journey (some early 2008 minivans are not supported through the DLC).

New Ford/Lincoln/Mercury Coverage Below lists the new Ford vehicle coverage for ACM and powertrain control module (PCM) crash data retrieval. For details on total coverage, refer to the Supported Ford Vehicles section of the CDR help file.

Ford • 2008 - 2009 Crown Victoria (ACM and PCM) • 2008 - 2009 Edge (ACM and PCM) • 2009 Focus (ACM only) Lincoln • 2008 - 2009 MKX (ACM and PCM) • 2008 - 2009 Town Car (ACM and PCM)

Dodge • 2008 – 2009 Voyager

Mercury

General Chrysler Changes

• 2008 - 2009 Grand Marquis (ACM and PCM)

• Added Pre-crash data graphs in all Chrysler CDR reports 102 Collision

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• Windows Vista (Home and Business for PC/Laptop Computers)

General Ford Changes • Added Pre/Post crash data graphs for all Ford PCM CDR reports • Added vehicle roll angle data and new pre-crash -5 second (10 sample/second) data parameters for 2009 Ford F150, Econoline & Escape

* CDR will not work correctly on international version of the above Windows (Non-US Windows) operating systems.

New GM Coverage For details on total GM coverage, refer to the Supported GM Vehicles section of this help file.

Added several Module SW IDs for: • 2008 - 2009 vehicles with SDMs that require 02003293 and 02003320 cable • 2008 - 2009 Light truck/SUV Rollover modules • 2008 - 2009 Pontiac G8 SDMs Improved the display of Rollover fault codes and Roll Rate data

Product Compatibility Information Below lists system compatibility information for version 3.2 of the CDR system software.

• Version 3.2 Software and CDR Vehicle Interface Module Compatibility This software version is compatible with the blue and green metal CDR interface modules marked with a “CAN plus” logo on its label. Other versions of the CDR module (black plastic or blue units without the “CAN plus” logo) are not supported and can cause the software to not function as intended.

Supported Operating Systems CDR Version 3.2 software is currently supported on the following operating systems (United States/Canada version only*): • Windows 2000 (PC/Laptop Computers) • Windows XP (Home and Pro for PC/Laptop Computers)

Crash Data Group is the exclusive distributor for Bosch Crash Data Retrieval software and Hardware

We can help you with: CDR Software Subscriptions CDR Software Renewals CDR System Kits CDR Cables CDR Adapters CDR Cases CDR Replacement Parts CDR Certification Training Contact CRASH DATA GROUP for ordering and special pricing information.

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Collision

103

W E N CSV Pro 2008 broke new ground in Crash Data Retrieval (CDR) data analysis by taking advantage of the new CDR program CSV (comma separated value) function for certain data sets allowing the end user to view and rearrange the recovered data into meaningful, clear and concise reports and graphs supplementing the original CDR report for Ford PCM "pre crash" downloaded data.

CSV Pro 2009 is a huge leap forward giving the end user not only the ability to analyze and graph Ford PCM reports but, with CDR version 3.1.1, import and analytical access to select Ford airbag control module data and Chrysler "pre-crash" and crash pulse data.

With CSV Pro 2009, the CDR end user can better deal with the massive quantities of data provided by the latest accessible modules and more effectively use that data together with a situationally complete crash analysis.

Some of the changes from CSV Pro 2008 • • • • •

The ability to graph crash pulse data by axis individually or with complementary axial data Select a "time zero" rather than adopt a pre-formatted time based on the end user's analysis of the event Import and evaluate Ford PCM "pre-crash data" Import and evaluate Chrysler airbag control module "pre-crash data" Import and evaluate Ford ACM crash pulse data from the latest modules for longitudinal and lateral acceleration and delta-V • Import and evaluate Chrysler ACM crash pulse data from the latest modules for longitudinal and lateral acceleration and delta-V, in some cases, together with "pre-crash data for the same download/module

Order your copy today - www.csv-pro.com The CSV Pro Excel Utility file is to be used in conjunction with Bosch CDR software. If you need to order the newest version of the Bosch CDR Software please visit the following URL: www.cdr-system.com.

CSV Pro 2009 includes support for Ford and Chrysler CDR CSV export files.

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Crash site evidenCe

A 1968 Mustang GT, driven by Lt. Frank Bullitt, is chasing a 1968 Dodge Charger R/T, driven by a man known only as “The Killer,” down Taylor Street on Russian Hill in San Francisco.

Collision: The International Compendium for Crash Research

For a full reconstruction of this 46 second chase sequence, visit www.edccorp.com/bullitt

HVE directly answers the following questions using Newton’s laws of motion:

Questions

Answers

Speed on Taylor St.

30 – 37 mph (both vehicles)

Driver Inputs

Mustang: 2-3 lb brake pedal force, 200 deg left steer onto Filbert, then 25-65 %WOT Charger: 3-5 lb brake pedal force, 175 deg left steer onto Filbert, then 70-75 %WOT

Maximum Undercarriage Impact Force

Mustang: Fx= -1730 lb, Fy= -13 lb, Fz= -2120 lb Charger: Fx= -8610 lb, Fy= -120 lb, Fz= -11100 lb

Maximum Suspension Force

Mustang: 4330 lb @ L/F; 3270 lb @ R/R Charger: 4810 lb @ R/F; 3530 lb @ L/R

Hubcaps Lost

Mustang: N/A (American Racing Mags) Charger: Five

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4/8/09 1:26 PM

Volume 4, Issue 1 - SPRING 2009

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Volume 4 Issue 1

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CDR Evidence: FAQs Forensic Photography

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Accuracy of Selected 2008

Chrysler ACM EDR’s During Braking

Other software may claim to answer these questions. Have you closely evaluated their claims and the basis for their results?

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