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Southwestern Collision Analysis
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Publications

McClafferty, K.J., German, A. "High-Tech Vehicle Safety Systems", Proc. of Canadian Multidisciplinary Road Safety Conference XVIII, Whistler, British Columbia, June 2008
Sophisticated electronic sensing and control systems are increasingly being integrated into the motor vehicle fleet to provide drivers with advanced occupant protection and collision avoidance mechanisms. There is currently no single source of information for the Canadian motoring public to obtain information on the operation and benefits of such new vehicle safety technologies. A project to develop a series of linked web pages outlining the major features of high-tech motor vehicle safety systems, in simple terms that will be readily assimilated by the general public, has been undertaken on behalf of the Canadian Association of Road Safety Professionals. The major concepts and functions of the systems described are illustrated by appropriate diagrams and/or photographs. Links are provided to additional technical information, performance evaluations, and external web sites providing supplementary data. The project includes advanced occupant restraints (seat belt pretensioners, load limiters, advanced frontal air bags, side air bags and head curtains), active head restraints, anti-lock braking systems, brake assist, traction control systems, electronic stability control systems, event data recorders, night vision systems, adaptive cruise control, blind spot detection and backup warning systems. The readily-accessible web pages provide useful information to the vehicle-buying public and will assist individuals to make informed choices for safety features that may only be available in certain makes and models and/or as optional equipment.

PDF fileThe full text paper is available for downloading (438 KB)

Undeployed seat belt pre-tensioner Deployed seat belt pre-tensioner
Undeployed seat belt pre-tensioner Deployed seat belt pre-tensioner

McClafferty, K.J., Shkrum M.J., Tiessen P.F., German, A., Comeau, J.L. "Event Data Recorders in the Analysis of Frontal Impacts", Proc. 51st AAAM Conference, Melbourne Australia, October, 2007

Evaluations of crash protection safety features require measures for quantifying impact severity. Velocity change (delta-V) is the major descriptor of collision severity used in most real-world crash databases. One of the limitations of delta-V is that it does not account for the time over which the crash pulse occurs (delta-t). Late model GM vehicles equipped with event data recorders capture the cumulative delta-V in 10 ms intervals over the crash pulse. Deceleration can be readily calculated from these data and provides a complementary measure of severity that has not previously been available for real world crashes. The relationship between maximum delta-V and deceleration was examined for different vehicle platforms involved in real world frontal impacts and frontal crash tests. Maximum deceleration was observed to be closely correlated to the maximum delta-V.

AAAMThe full text paper is available on-line courtesy of the
Association for the Advancement of Automotive Medicine

Event data recorder (EDR) download

McClafferty, K.J., Green R.N., Tiessen P.F., Brown J., German, A., Comeau, J.L. "A Comparison of Real World Frontal Impacts and Staged Crash Tests", Proc. of Canadian Multidisciplinary Road Safety Conference XVII, Montreal, Quebec, June 2007

Real world evaluations of motor vehicle crash protection safety features require measures for quantifying impact severity. Velocity change (delta-V) is the primary descriptor of collision severity used in most databases of real world crash information. Historically, the delta-V has been calculated using conventional accident reconstruction techniques such as damage or momentum analysis. A major shortcoming of the sole use of delta-V as a measure of crash severity is the lack of information on the timing of the velocity change, the delta-T of the collision event. Late model vehicles equipped with event data recorders record the time history of the delta-V during the crash pulse. The average deceleration that occurs over different time durations can often be readily calculated from the data recorded by the EDR. This paper examines the recorded longitudinal delta-V data for 104 real world collisions involving 1996 to 2005 Chevrolet Cavaliers and Pontiac Sunfires that were equipped with event data recorders. The real world crash pulse data is compared to similar data for staged crash tests. The relationship between longitudinal delta-V and deceleration is evaluated for different frontal impact modes.

PDF fileThe full text paper is available for downloading (202 KB)

Air bag firing times

Foster, M., McClafferty, K.J., Shkrum, M.J., Tiessen, P.F. Hibbert, W., Carter, D. "Event Data Recorders: An Impartial Witness", Proc. of Canadian Multidisciplinary Road Safety Conference XVII, Montreal, Quebec, June 2007

Real world field studies can yield tremendous insight into the factors that precipitate motor vehicle collisions. The strength of such in-depth studies is the quality of the data obtained, especially when this data is based on solid physical evidence. While witness statements can provide some clarification of crash events, the fallibility of eyewitness memory and bias can result in substantial errors. Furthermore, many fatal single vehicle crashes have no witnesses leaving investigators to rely solely on scientific analysis of the available physical evidence. High- level data from real-world collisions regarding crash severity, pre-crash speeds, perception and reaction, evasive inputs and seatbelt use are of great importance in the resolution of legal issues and are critical data elements to researchers conducting studies into vehicle collisions.

Cumulative delta-V curves

Many late-model General Motors light-duty vehicles are equipped with event data recorders (EDRs) that capture data relating to the crash pulse, the time history of the velocity change, and in some cases the time history of a number of pre-crash data elements including, vehicle speed, brake switch status, throttle position and engine speed. The objective of this research is to examine the role of the EDR in the reconstruction and understanding of fatal crashes. Thirteen real world collisions involving a driver fatality in a vehicle equipped with an EDR were studied. In each case a detailed collision investigation and reconstruction was conducted to determine the crash events and validate the recorded data. The EDR data greatly improved the understanding of pre-crash events and often provided critical insight that otherwise would have remained unknown.

PDF fileThe full text paper is available for downloading (736 KB)

Green, R.N., Shkrum, M.J., McClafferty, K..J. "Guidance for Research Teams: Injury Data Collection for Crash Reconstruction Studies", Proc. of Canadian Multidisciplinary Road Safety Conference XVII, Montreal, Quebec, June 2007

More than thirty years ago, the Road Safety and Motor Vehicle Regulation Directorate of Transport Canada began establishing multidisciplinary accident research teams across Canada. Historically, these teams have been located in universities under the direction of one or more professors who have an interest in, and a commitment to, road traffic safety. The motivation for this data collection project is to provide the ministry with the necessary field research data that will identify important safety issues and monitor responses to government rule making.

The multidisciplinary aspect of the teams is essential, providing engineering skills for crash reconstruction, and medical knowledge to explain injury data and suggest likely injury biomechanics. Cooperation of the policing and legal communities has been most helpful in locating and obtaining access to crash sites and damaged vehicles.

Collision reconstruction studies involve inspecting and photographing damaged vehicles, and roadway and roadside evidence. One of the more challenging aspects of data collection by the teams involves obtaining injury data on the crash victims. In completing most reconstruction reports it is impractical to obtain the consent of injured individuals whose personal health information is required. This has required establishing and maintaining the trust and cooperation of the legal custodians of recorded injury data, in keeping with recognized legal safeguards.

Salus Populi Supremus Lex

In order to manage the tension between the need to protect confidentiality and the public's right to know, when such research contributes to public safety, federal and provincial governments have enacted legislation that recognizes the value of such research. In support of this research, these statutes spell out necessary safeguards for the protection of confidentiality. This paper outlines these developments and reviews how the multidisciplinary accident research teams have been collecting injury data while recognizing these necessary constraints.

When crash data collection involves a large urban area, or when a particular study requires statistical sampling of a broad geographical area, it is challenging for a reconstruction team to establish a working relationship with many health information custodians. In spite of the best efforts of medically trained team members, inadequate case sampling may result in such studies being curtailed or abandoned. This paper provides research teams with the background information and guidance to most effectively collect, utilize and disclose this sensitive personal injury information.

PDF fileThe full text paper is available for downloading (307 KB)

George, A., McClafferty, K.J., Shkrum, M.J., Tiessen, "To Deploy of Not to Deploy: Frontal Impact Case Studies", Proc. of Canadian Multidisciplinary Road Safety Conference XVII, Montreal, Quebec, June 2007

Front airbags in conjunction with seatbelts are known to protect occupants from incurring serious injury or fatality in high speed crashes. However, airbag deployment in low to moderate severity crashes has often resulted in disproportionate injuries and has caused considerable public controversy. Despite subsequent improvements in front airbag design, they can cause serious injury in some collisions. Accurate determination of the role of the airbag in such cases is critical for improving restraint system design, developing motor vehicle safety standards, and resolving medico-legal issues. This study investigated the role of the front airbags in two moderate- severity (delta-V = 27 km/h) single vehicle frontal impacts where there were unusual fatal outcomes. In both cases, either trauma from the collision or airbag involvement was hypothesized to be involved.

Non-deployment and deployment impacts
Non-deployment Deployment

In one case, the front airbags did not deploy and the belted male driver was found dead at the scene. Post-mortem evidence indicated that the occupant had a bicuspid aortic valve and sudden aortic dissection likely precipitated by the collision. In the other case, a belted elderly female front passenger sustained severe head and neck injuries due to interaction with the first stage of the advanced passenger's airbag, and subsequently died in hospital. The elderly female had an underlying arthritic degenerative cervical spinal disc and facet disease which contributed to the injuries. In-depth investigation and reconstruction, including linking crash and injury data was critical for understanding occupant injury mechanisms, and determining the role of the front airbags in these two cases.

PDF fileThe full text paper is available for downloading (2.4 MB)

German, A., Comeau, J.L., Monk, B., White, J., McClafferty, K. "Momentum and Event Data Recorders", Proc. of Canadian Multidisciplinary Road Safety Conference XVII, Montreal, Quebec, June 2007

The principle of conservation of linear momentum has long been used by collision reconstructionists to obtain estimates of initial vehicle speeds in vehicle-to-vehicle crashes. Because, in general, both vehicle speeds are unknown, the method requires extensive scene evidence to provide measures of the vehicle run-out speeds, and the approach and departure angles of the vehicles with respect to the collision. Many late-model vehicles, notably those manufactured by General Motors and Ford, are now equipped with event data recorders (EDR's) that record certain vehicle parameters when a collision occurs. Nominally, the data parameters of interest that might be available for a vehicle equipped with an EDR are the vehicle's impact speed, the change in vehicle velocity (delta-V) occurring in the collision, and the principal direction of force (PDOF) experienced by the vehicle. Effectively, EDR's provide collision investigators with one or more instrumented vehicles in the crash, and give a source of new data that can be integrated into the reconstruction process. The present work demonstrates how the recorded parameters can be utilized in momentum-based calculations, and notes the limitations that may apply to such use. It is also noted that collision situations where both EDR's and adequate scene evidence are available provide real-world \u201cexperiments\u201d whereby the conservation of momentum methodology may be readily verified.

PDF fileThe full text paper is available for downloading (502 KB)

Change in momentum and velocity

In the Archives

German A, Comeau J-L, McClafferty KJ and Green RN; Event Data Recorders and Traffic Safety Research; Proc. 20th ITMA World Congress; 16-18 October, 2006; Melbourne, Australia (Published abstract)

McClafferty K, Tiessen P, Green R, Brown J, German A and Comeau J-L; A Comparison of Real World Frontal Impacts and Staged Crash Tests; Proc. CMRSC-XVI; Winnipeg, Manitoba; June 11-14 2006 (Published abstract)

Green R.N., McClafferty, K.J. "A Review of Jurisprudence Regarding Event Data Recorders: Implications for the Access and Use of Data for Transport Canada Collision Investigation, Reconstruction, Road Safety Research and Regulation", Transport Canada website

McClafferty, K.J., Tiessen, P.F., German A., "The Use of Event Data Recorders in the Analysis of Real World Collisions: Tales from the Silent Witness", In: Contemporary Issues in Road User Behavior ?ISBN 1-59454-268-6, Eds.: D.A. Hennessy and D.L.Wiesenthal pp. 249-260 © 2004 Nova Science Publishers, Inc.

McClafferty, K.J., Tiessen, P.F., German, A. "Comparisons of EDR-Recorded Delta-V to Delta-V Calculated by Crush Analysis", Proc. of Canadian Multidisciplinary Road Safety Conference XIV, Ottawa, Ontario, June 2004

McClafferty, K.J., Tiessen, P.F., German, A., Chan, J., "A Study of Pre-Crash Events Using Information Retrieved from Event Data Recorders", Proc. of Canadian Multidisciplinary Road Safety Conference XIII, Banff, Alberta, June 2003

Shkrum, M., McClafferty, K., Nowak, E., German, A., "Driver and Front Seat Passenger Fatalities Associated with Airbag Deployment. Part 1: A Canadian Study," Journal of Forensic Science

Shkrum, M., McClafferty, K., Nowak, E., German, A., "Driver and Front Seat Passenger Fatalities Associated with Airbag Deployment. Part 2: A Review of Injury Patterns and Investigative Issues," Journal of Forensic Science

McClafferty, K.J., Tiessen, P.F., Shkrum, M.J., German, A., "Fatalities Involving Tilt-Bed Trucks: Underride and Poor Conspicuity ", Proc. of Canadian Multidisciplinary Road Safety Conference XII, London, Ontario, June 10-13, 2001

Dr. Charles H. Miller Award 2001 Dr. Charles H. Miller Award Winner
Le gagnant du prix Dr Charles H. Miller 2001

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

White, J., Guérette, C., Bruneau, J.F., Chan, J., McClafferty, K., Pepper, C., "School Bus Pre-Stop Warning Lights Study Status Report", Proc. of Canadian Multidisciplinary Road Safety Conference XII, London, Ontario, June 10-13, 2001

Shkrum, M.J., McClafferty, K.J., German, A., Dalmotas, D.J., Nowak, E.S., "Canadian Case Studies of Driver and Front Passenger Fatality Associated with Airbag Deployment", Presented at the 49th Meeting of the American Academy of Forensic Sciences, Orlando, Florida, February 15-20, 1998

McClafferty, K.J., Tiessen, P.F., Glazduri, V., Shkrum, M.J., German, A., Nowak, E.S., "Driver Fatalities in Frontal Impacts", Proc. of Canadian Multidisciplinary Road Safety Conference XI, Halifax, Nova Scotia, Ontario, May 9-12, 1999

McClafferty, K.J., Shkrum, M.J., Chan, J., German, A., "A Multidisciplinary Study of a Canadian Airbag Fatality", Proc. Canadian Multidisciplinary Road Safety Conference X, Toronto, Ontario, June 9-11, 1997

McClafferty, K.J., Chan, J., German, A., Nowak, E.S., "The Fundamentals of Damage Analysis", Proc. Canadian Multidisciplinary Road Safety Conference X, Toronto, Ontario, June 9-11, 1997

Shkrum, M.J., Green, R.N., McClafferty, K.J., Nowak, E.S., "Aortic Injury in Fatal Motor Vehicle Collisions", Presented at the 48th Meeting of the American Academy of Forensic Sciences, Nashville, Tennessee, February 19-24, 1996

German, A., McClafferty, K.J., Dalmotas, D.J., Nowak, E.S., "Real-World Collision Experience for Airbag Technology", Proc. of the 1996 Canadian Society for Mechanical Forum, May 7-9, 1996

White, J., McClafferty, K.J., Nowak, E.S., Orton R.B., Tokarewicz. A.C., "Ocular Alkaline Burn Associated with Automobile Air Bag Activation", Canadian Medical Association Journal

McClafferty, K.J., Nowak, E.S., Lane, P.L., "High-Severity Collisions Involving Ambulances," Poster Presentation, Proc. 39th AAAM Conf., Chicago, Illinois, October, 1995

White, J., McClafferty, K.J., Nowak, E.S., Orton R.B., Tokarewicz. A.C., "Case Study - Alkali Eye Injury Secondary to Air Bag Deployment," Proc. Canadian Multidisciplinary Road Safety Conference IX, Montreal, Quebec

Shkrum, M.J., Green, R.N., McClafferty, K.J., Nowak, E.S., "Skull Fractures in Fatalities Due to Motor Vehicle Collisions," Journal of Forensic Sciences, February 1994, pp. 107-122.

Lane, P.L., McClafferty, K.J., Nowak, E.S., "Pedestrians in Real World Collisions," Journal of Trauma, January 1994, pp. 231-236.

Lane, P. L., McClafferty, K. J., Nowak, E. S.; Pedestrians in Real World Collisions; Proc. of the Annual Meeting of the Royal College of Physicians and Surgeons, Toronto, Ontario, October, 1992.

Lane, P.L., McClafferty, K.J., Green, R.N., Nowak, E.S.; "A Study of Injury Producing Crashes on Median Divided Highways in Southwestern Ontario," Proc. 36th AAAM Conf., Portland, Oregon, October, 1992

German, A., Green, R.N., McClafferty, K.J., Nowak, E.S., Tiessen, P.F.; "The Occurrence of Fatality to Restrained Occupants of Passenger Cars in Southwestern Ontario," Proc. Canadian Multidisciplinary Road Safety Conference VII, Vancouver, British Columbia, June 17-19, 1991

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