Vehicle Safety Ratings Estimated from Police Reported Crash Data: 2005 Update
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VEHICLE SAFETY RATINGS ESTIMATED FROM POLICE REPORTED CRASH DATA: 2005 UPDATE AUSTRALIAN AND NEW ZEALAND CRASHES DURING 1987-2003 by Stuart Newstead Max Cameron & Linda Watson Report No. 241 June 2005 Project Sponsored By ii MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE REPORT DOCUMENTATION PAGE Report No. Report Date ISBN Pages 241 June 2005 0 7326 2311 1 67 + Appendices Title and sub-title: VEHICLE SAFETY RATINGS ESTIMATED FROM POLICE REPORTED CRASH DATA: 2005 UPDATE AUSTRALIAN AND NEW ZEALAND CRASHES DURING 1987-2003 Author(s) Type of Report & Period Covered Newstead, S.V., Cameron, M.H. and Watson, L.M. Summary Report, 1982-2003 Sponsoring Organisations - This project was funded as contract research by the following organisations: Road Traffic Authority of NSW, Royal Automobile Club of Victoria Ltd, NRMA Ltd, VicRoads, Royal Automobile Club of Western Australia Ltd, Transport Accident Commission and Land Transport New Zealand, the Road Safety Council of Western Australia, the New Zealand Automobile Association and by a grant from the Australian Transport Safety Bureau Abstract: Crashworthiness ratings measure the relative safety of vehicles in preventing severe injury to their own drivers in crashes whilst aggressivity ratings measure the serious injury risk vehicles pose to other road users with which they collide. Updated crashworthiness ratings and aggressivity ratings for 1982-2003 model vehicles were estimated based on data on crashes in Victoria and New South Wales during 1987-2003 and in Queensland, Western Australia and New Zealand during 1991-2003. Both crashworthiness and aggressivity were measured by a combination of injury severity (the risk of death or serious injury given an injury was sustained) and injury risk (the risk of injury given crash involvement). The ratings were adjusted for the sex and age of the person whose injury outcome was being measured, speed limit at the crash location, number of vehicles involved where relevant, the jurisdiction in which the crash occurred and the year in which the crash occurred. These factors were strongly related to injury risk and/or severity. The ratings estimate the risk of being killed or admitted to hospital when involved in a crash, to a degree of accuracy represented by the confidence limits of the rating in each case. Crashworthiness estimates and their associated confidence limits were obtained for 288 vehicle models classified into 12 market groups. They were sufficiently sensitive that they were able to identify 149 models of passenger cars, four wheel drive vehicles, passenger vans and light commercial vehicles that have superior or inferior crashworthiness characteristics compared with the average vehicle. A new aggressivity rating was successfully developed which extended the previous rating to consider the injury outcomes of not only drivers of other vehicles but also of unprotected road users such as pedestrians, cyclists and motorcyclists. The new aggressivity rating measured the risk of death or serious injury to other drivers or unprotected road users impacted by the focus vehicle. In addition to the above factors this rating was also adjusted for type of other road user impacted as this factor was strongly related to injury severity and varied between vehicle models. New aggressivity rating estimates and their associated confidence limits were obtained for 261 vehicle models and were sufficiently sensitive that they were able to identify 115 models of passenger cars, four wheel drive vehicles, passenger vans and light commercial vehicles that have superior or inferior aggressivity characteristics compared with the average vehicle. Also investigated was the relationship between vehicle crashworthiness and the year of manufacture of Australian passenger and light commercial vehicles manufactured from 1964 to 2003. Trends were examined by year of manufacture both for the fleet as a whole and by market group for vehicles manufactured from 1982 to 2003. The results of this report are based on a number of assumptions and warrant a number of qualifications that should be noted. Key Words: (IRRD except when marked*) Injury, Vehicle Occupant, Collision, Passenger Car Unit, Passive Safety System, Statistics Disclaimer: This Report is produced for the purposes of providing information concerning the safety of vehicles involved in crashes. It is based upon information provided to the Monash University Accident Research Centre by VicRoads, the Transport Accident Commission, the New South Wales Roads and Traffic Authority, NRMA Ltd, Queensland Transport, the Western Australian Department of Main Roads and Land Transport New Zealand. Any republication of the findings of the Report whether by way of summary or reproduction of the tables or otherwise is prohibited unless prior written consent is obtained from the Monash University Accident Research Centre and any conditions attached to that consent are satisfied. A brochure based on this report is available from the sponsoring organisations and may be freely quoted. Reproduction of this page is authorised Monash University Accident Research Centre Building 70, Monash University Victoria 3800, Australia. Telephone: +61 3 9905 4371, Fax: +61 3 9905 4363 VEHICLE CRASHWORTHINESS AND AGGRESSIVITY RATINGS: 1987 TO 2003 DATA iii iv MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE EXECUTIVE SUMMARY This report describes the development of further updated vehicle safety ratings for 1982- 2003 model vehicles. The ratings produced cover both vehicle crashworthiness and aggressivity. Crashworthiness ratings measure the relative safety of vehicles in preventing severe injury to their own drivers in crashes whilst aggressivity ratings measure the serious injury risk vehicles pose to other road users with which they collide. Both measures are estimated from data on real crashes reported to police. The update is based on crash data from Victoria and New South Wales during 1987-2003 and from Queensland, Western Australia and New Zealand during 1991-2003. The rating of vehicle crashworthiness through analysis of real crash data, as carried out here, and through crash tests carried out by consumer groups such as the Australian New Car Assessment Program is likely to have encouraged manufacturers to improve vehicle safety. A new aggressivity rating measure based on collisions between the vehicle being rated and both other vehicles and unprotected road user was successfully developed. Previously, the aggressivity ratings published were based only on the analysis of injury outcomes to drivers in collisions between two vehicles. Through incorporation also of crashes involving unprotected road users including pedestrians, bicyclists and motorcyclists in the aggressivity rating, the aggressivity measure is more representative of the threat of subject model cars to all vulnerable road users. In addition, increased crash numbers relating to unprotected road users in the aggressivity measure resulted in ratings with greater accuracy and coverage. Crashworthiness ratings were measured by a combination of injury severity (of injured drivers) and injury risk (of drivers involved in crashes). Crashworthiness injury severity was based on 237,069 drivers injured in crashes in Victoria during 1987-2003, in New South Wales during 1987-1998 and in Queensland, Western Australia and New Zealand during 1991-2003. Crashworthiness injury risk was based on 1,144,092 drivers involved in crashes in New South Wales during 1987-2003 and Western Australia and Queensland during 1991-2003 where a vehicle was towed away. The crashworthiness ratings were adjusted for the driver sex and age, the speed limit at the crash location, the year in which the crash occurred, the jurisdiction in which the crash occurred and the number of vehicles involved in the crash. These factors were found to be strongly associated with injury risk and injury severity. Adjustments were made with the aim of measuring the effects of vehicle factors alone, uncontaminated by other factors available in the data that affected crash severity and injury susceptibility. The crashworthiness ratings estimate the risk of a driver of the focus vehicle being killed or admitted to hospital when involved in a tow-away crash, to a degree of accuracy represented by the confidence limits of the rating in each case. Statistically reliable crashworthiness ratings were calculated for 288 individual vehicle models manufactured between the years 1982-2003. The estimates and their associated confidence limits were sufficiently sensitive that they were able to identify 149 models of passenger cars, four wheel drive vehicles, passenger vans and light commercial vehicles that have superior or inferior crashworthiness characteristics compared with the average crashworthiness across all vehicles in the data. Vehicles were classified into one of 12 market groups for presentation of the ratings with average crashworthiness of vehicles in each market group estimated. ii MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE The new measure of aggressivity was calculated for 261 models of Australian and New Zealand passenger vehicles manufactured between the years 1982-2003. The new aggressivity ratings estimate the risk of a vehicle driver or unprotected road user impacting with the focus vehicle model being killed or admitted to hospital when involved in a crash. The degree of accuracy of the aggressivity ratings is represented by the confidence limits of the rating in each case. The estimates