Traffic Accidents Investigation preview.pdf - Thomson Reuters

140 

Traffic accidents 

investigation, analysis and 

reconstruction 

updated by 

G Rechnitzer B Eng (Hons), M Eng Sc, PhD, MIEAust, CPEng, 

FSIA, MSAEA 

S Richardson B Eng (Mech), MSc (MVT), MIEAust, MSAEA 

A Short BA (Physics), MSc, BMED, D Phil (Oxon) 

T Orton B S Mechanical Engineering [UCSB] 

[Updating authors, Update 46, December 2008] 

by 

G Rechnitzer B Eng (Hons), M Eng Sc 

J Lenard B Eng (Hons), MA 

W Keramidas B App Sc, BA 

[Original authors] 

© 2008THOMSONREUTERS 

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Update: 46

EXPERT EVIDENCE 

The views expressed in this work are those of the authors. 

Although considerable care has been taken in regard to ensuring the accuracy of 

the work presented, the responsibility for the correct use, interpretation and 

verification of accuracy of any materials used must rest with the user. 


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Expert Evidence

Author information 

Dr George Rechnitzer is a partner and Principal Forensic Engineer with Delta-V 

Experts International Pty Ltd (see www.dvexperts.net) a Forensic Engineering and 

Safety Solutions consultancy. He has extensive experience in the application of the 

engineering sciences to safety in many areas including road safety, crashworthiness of 

all vehicle types, occupational health and safety, accident and incident investigation 

and reconstruction, analysis and countermeasure development for injury prevention. Dr 

Rechnitzer was a Senior Research Fellow at the Monash University Accident Research 

Center for some 12 years, and has carried out major projects for the Australian 

Defence Force, Vic Roads, Federal Office of Road Safety, Victorian Work Cover 

Authority and the Victorian Occupational Health and Safety Commission. He has also 

carried out a number of in-depth investigations for the State Coroner; consultancies on 

vehicle safety related projects for BHP, Australia Post, SECV and the Australian 

Industrial Relations Commission, amongst others. Dr Rechnitzer provides expert 

evidence for litigation cases in Australia and the USA, and his work has been published 

extensively with over 80 publications including contributing chapters in books relating 

to traffic accidents, accident investigation and reconstruction; and has made 

presentations at over 60 conferences and seminars, both nationally and at international 

forums. 

Dr Rechnitzer graduated in 1971 from Monash University with a Bachelor of 

Engineering (Civil) (Hons), has a Master Engineering Science degree from Melbourne 

University (1979), and a PhD from Monash University (2003). He is a Member of the 

Institution of Engineers and Sociey of Automotive Engineers, a Fellow of the Safety 

Institute of Australia and is Chair of its National Technical Panel. 

Dr Rechnitzer may be contacted at: 

Principal Forensic Engineer 

DVExperts International 

377 St Georges Road 

FITZROY NORTH VIC 3068 

AUSTRALIA 

Telephone: +61 (0)3 9481 2200 

Mobile +61 (0)418 998 158 

Fax + 61 (0)3 9481 2277 

Email: grechnitzer@dvexperts.net 

Website: http://www.dvexperts.net 

Shane Richardson is a partner and Principal Forensic Engineer with Delta-V Experts 

International Pty Ltd (see www.dvexperts.net) a Forensic Engineering and Safety 

Soultions consultancy. Shane has provided expert evidence in the Supreme, County 

and Magistrates Courts related to collision/incident investigations for rollover collisions, 

heavy equipment, tram collisions, boat collisions, vehicle dynamics, collision damage, 

crashworthiness, lines of sight, motorcycle collisions, bicycle collisions, pedestrian 

collisions, human impact, ballistics and vehicle data recorders. Shane is a Mechanical 

Engineer with 20 years experience in applying systems engineering methods to the 

procurement, specifications development, and design of automotive, military, 

mechanical and safety systems. Shane evaluated technical integrity issues such as: 

design, documentation, drawings, systems of work, maintenance and reliability and 

investigated equipment faults and failures. 

He has published national and international technical papers, and is currently 


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Update: 46


completing his PhD within the Civil Engineering Department, Monash University. The 

focus of his research thesis is Roll Over Protection Systems for 4x4 vehicles. 

Mr Richardson may be contacted at: 




AUSTRALIA 

Telephone: +61 (0)3 9481 2200 

Mobile +61 (0)409 011 362 

Fax + 61 (0)3 9481 2277 

Email: srichardson@dvexperts.net 


Dr Andrew Short has been publishing, researching and practising in the area of 

biomechanics since 1995 and specialises in the application of statistical methods to 

establish the probability of injury in reported circumstances. 

Dr Short graduated from Trinity College Dublin (BA in Physics) and received 

scholarships to attend Imperial College London (MSc in Engineering and Physical 

Sciences in Medicine) and Oxford University where he received a Doctorate in 

Engineering Science, has spent two years as a Research Fellow at the Accident 

Research Centre, Monash University, where he conducted projects relating to arm 

fracture, serious spinal and head injury and developed strong industry links for 

investigating novel injury prevention devices. Dr Short is the Lecturer in cellular and 

tissue biomechanics at the University of Melbourne. 

Dr Short is a consutant biomechanics engineer and provides expert reports on cases 

of personal injury. These cases include determination of injury outcomes in the 

reported or reconstructed circumstances of a vehicle collision. Dr Short has specific 

skills in comparing injury outcomes for persons wearing and then not wearing a 

seatbelt and the reconstruction of pedestrian impacts where the standard throw 

distance calculations do not apply (MADYMO). 

In addition, Dr Short provides rounded, statistical, holistic and biomechanically sound 

analysis of work processes. 

Dr Short may be contacted at: 

Biomechanics Engineer 




AUSTRALIA 

Telephone: +61 (0)3 9481 2200 

Mobile +61 (0)415984519 

Fax + 61 (0)3 9481 2277 

Email: ashort@dvexperts.net 


Tia Orton completed her Bachelor of Science Degree in Mechanical Engineering at the 

University of California in Santa Barbara (UCSB). While at UCSB, Tia held the coveted 

position of Undergraduate Teaching Assistant for Mechanical Engineering Drafting & 

Design. Following an internship at General Motors, Tia opted for a career in the field of 

independent transportation safety research with Safety Analysis and Forensic 


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Expert Evidence

Engineering (SAFE), a leading US automotive safety research firm. 

Throughout her six-year term at SAFE, Tia became extremely proficient in automotive 

crashworthiness analysis, research and litigation support. Tia’s work at SAFE included 

extensive analysis, testing and research related to vehicle rollover and other crash 

types. Much of the ground-breaking research that Tia encountered at SAFE was 

conducted by DVExperts International, leading to Tia taking a position working for 

DVExperts in Australia in October 2006. 

Since joining DVExperts, Tia has worked on many different cases ranging from car, 

motorcycle, truck and bus collisions, pedestrian impacts, rollovers, and structural and 

road design. Tia has also authored numerous peer-reviewed technical publications and 

has presented research to the US National Highway Traffic Safety Administration 

(NHTSA) on various subjects related to vehicle design. 

Ms Orton may be contacted at: 




AUSTRALIA 

Telephone: +61 (0)3 9481 2200 

Fax + 61 (0)3 9481 2277 

Email: torton@dvexperts.net 


DVExperts is a forensic engineering and safety solutions company specializing in 

accident investigation and reconstruction, failure analysis, road safety, vehicle 

crashworthiness, workplace safety and safety solutions. 


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Update: 46


OVERVIEW ..................................................................................................................... [140.10] 

Accident reconstruction ..................................................................................................... [140.50] 

Traffic accident statistics for Australia ............................................................................... [140.90] 

Road safety – Historic trends ................................................................................ [140.100] 

Biomechanics in collisions............................................................................................... [140.140] 

Occupant motion in frontal collisions............................................................................... [140.180] 

Injury biomechanics in collisions ..................................................................................... [140.220] 

Crash test dummies and associated computer models ........................................ [140.230] 

Pedestrians in collisions .................................................................................................. [140.270] 

Injury criteria and tolerance levels for serious injury....................................................... [140.310] 

Crashworthiness and Australian design rules and standards......................................... [140.340] 

RECONSTRUCTION TECHNIQUES 

1.1 Introduction ........................................................................................................... [140.380] 

1.2 Crash scene ......................................................................................................... [140.400] 

1.3 Damaged vehicles ................................................................................................ [140.440] 

1.4 Tyre marks 

1.4.1 Introduction ................................................................................................... [140.460] 

1.4.2 Rolling prints ................................................................................................. [140.470] 

1.4.3 Skid marks .................................................................................................... [140.480] 

1.4.4 Scuff marks................................................................................................... [140.490] 

1.4.5 Friction and the tyre-road interaction............................................................ [140.510] 

1.5 Estimation of speed from skid marks................................................................... [140.550] 

1.5.1 Limitations..................................................................................................... [140.560] 

1.5.2 Accuracy ....................................................................................................... [140.570] 

1.6 Estimation of speed from yaw marks................................................................... [140.590] 

1.6.1 Determing the yaw radius............................................................................. [140.600] 

1.6.2 Limitations..................................................................................................... [140.610] 

1.6.3 Accuracy ....................................................................................................... [140.620] 

1.7 Measurement of friction........................................................................................ [140.640] 

1.7.1 Vehicle test skids .......................................................................................... [140.650] 

1.7.2 Limitations..................................................................................................... [140.660] 

1.7.3 Test skids using accelerometers................................................................... [140.670] 

1.7.4 Drag tyre and drag sled................................................................................ [140.680] 

1.7.5 The British portable skid resistance tester ................................................... [140.690] 

1.7.6 Friction values from tables............................................................................ [140.700] 

1.8 Leaps, flips and vaults 

1.8.1.1 Estimation of speed ................................................................................... [140.740] 

1.8.1.2 Limitations.................................................................................................. [140.750] 

1.8.1.3 Accuracy .................................................................................................... [140.760] 

1.9 Exterior vehicle damage .................................................................................................. 

1.9.1 Introduction ................................................................................................... [140.780] 

1.9.2 Structural performance ................................................................................. [140.790] 

1.9.3 Collision type ................................................................................................ [140.800] 

1.9.4 Crush profile ................................................................................................. [140.810] 

1.9.5 Estimation of speed from vehicle damage ................................................... [140.820] 

1.10 Interior vehicle inspection .............................................................................................. 

1.10.1 Seat belt use............................................................................................... [140.840] 

1.10.2 Intrusion ...................................................................................................... [140.860] 

1.11 Mechanisms of injury ..................................................................................................... 

1.11.1 Signs of contact .......................................................................................... [140.890] 

1.11.2 Occupant motion and mechanisms of injury .............................................. [140.900] 

1.11.3 Other ........................................................................................................... [140.910] 

1.12 Computers and software .................................................................................... [140.930] 

1.13 Documentation.................................................................................................... [140.950] 

Case histories................................................................................................................ [140.1000] 

1.14 Civil cases ........................................................................................................ [140.1020] 

1.14.1 Train and truck, level crossing collision.................................................... [140.1020] 

1.14.2 Pedestrian impact ..................................................................................... [140.1030] 

1.14.3 Motorcycle and car collision ..................................................................... [140.1040] 


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TABLE OF CONTENTS 

1.15 Culpable driving................................................................................................ [140.1070] 

1.15.1 Two vehicle head on collision................................................................... [140.1070] 

APPENDIX 1: SYMBOLS AND GLOSSARY OF TERMS................................. [140.1100] 

APPENDIX 2: PERCEPTION AND REACTION TIME....................................... [140.1200] 

APPENDIX 3: FORCES AND LAWS OF MOTION ............................................ [140.1300] 

FIGURES..................................................................................................................... [140.1640] 

Authors’ Preface 

It has been over 10 years since the original chapter was written. It was motivated by the need 

for a much stronger foundation of science and engineering principles in the presentation of 

expert evidence in courts and tribunals for transport involved collisions. 

Since that time much has progressed in terms of road safety improvements [vehicle 

crashworthiness advances, road infrastructure investments and road rules and enforcement]. On 

the other hand the basic physics and engineering principles have, of course, not changed and 

thus the fundamentals of what we present in this updated chapter are retained, although we 

hope made clearer, with revisions added by Shane Richardson, Dr Andrew Short and Ms Tia 

Orton. 

Importantly the authors wish to acknowledge that this Chapter also owes its genesis in part to 

two of the previous co-authors Mr William Keramidas and Mr Jim Lenard. 

We have provided new case examples taken from the large number of cases we have done over 

the last few years. Dr Andrew Short has provided additional information on injury mechanism 

and biomechanics relating to collisions. 

We hope that this primer aimed at the legal fraternity, will be read by all who are involved in 

transport accidents and collisions. We welcome any feedback or queries, with contact details 

provided at the end of the Chapter. 

Please Note: The views expressed in this work are those of the authors. Although considerable 

care has been taken in regard to ensuring the accuracy of the work presented, the 

responsibility for the correct use, interpretation and verification of accuracy of any materials 

used must rest with the user. 

[The next text page is 140-1051] 


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OVERVIEW 

[140.10] The many thousands of collisions which occur in Australia each year give rise to 

many actions, from property insurance claims, medical treatment, compensation claims, 

criminal charges for culpable driving, coronial inquests, product liability and other legal 

actions, road safety research and so on. The list is large. At the heart of many of these actions 

is the need to establish, as clearly and accurately as possible, particular and relevant details 

potentially relating to any phase of the incident. The result of the approximately 160,000 

tow-away crashes in Australia each year is around 1,600 fatalities and 46,000 serious injuries. 

Typical questions include, “How fast was the vehicle travelling”, “What was in its path”, 

“What action was taken by the driver”, “Who was driving”, “How did the vehicle design 

perform in terms of crashworthiness”, “How did the vehicles impact”, “How was the 

occupant injured” and so forth. Queries come from a host of interested parties, including 

insurance companies, police, coroners, road safety researchers, Federal and State regulatory 

authorities, vehicle owners, vehicle manufacturers and, of course, lawyers. The reasons for the 

queries can range from road safety research programs, product liability litigation, to driving 

prosecutions and insurance claims. 

Traffic accident reconstruction is aimed at providing the answers, if possible, to these 

questions. 

This chapter provides an introduction to the science of traffic accident investigation: analysis 

and reconstruction; current methodologies, procedures and limitations; expertise required; and 

questions for vetting expert witnesses. It is not intended – nor is it possible in the space 

available – to be a treatise on the subject, but it can provide those concerned with traffic 

accidents with a brief background and insight into what can be done, what information is 

needed and what questions need to be considered. 

With the great advances in techniques of computer analysis and graphic presentation, it is 

perhaps more important than ever not to confuse technical sophistication with accuracy and 

quality. Sophisticated technology may merely transform poor-quality data and analysis into 

impressive-looking but still poor-quality results. It is our objective to encourage the full and 

effective use of modern accident investigation techniques and also to sharpen the focus on 

ensuring that expert opinions, procedures and results are subject to due and appropriate 

scrutiny. 

Whilst experts can present technical reports and argue their position in Court, our experience is 

that lawyers, barristers, judges must also become more conversant with the principles outlined 

in this chapter. It remains a difficult and challenging exercise to present succinctly such science 

based material in court, where the science rather than the impression of science must be 

properly explained and completely understood by decision makers. This then leads to the 

further need for effective cross examination of experts based on a better understanding of the 

principles outlined in this Chapter. Thus our work as experts can often lose its full impact 

without the partnership of a technically well-informed legal team. Perhaps this is rather 

obvious; nonetheless it is vital that it is always recognised. 

Please refer to the appendices to this chapter in order to fully understand the explanations 

given below: 

Appendix 1: Symbols and Glossary of Terms 


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Appendix 2: Perception and Reaction time 

Appendix 3: Forces and Laws of Motion 

Appendix 4: Figures 

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