Vehicle Safety Ratings Estimated from Police Reported Crash Data: 2007 Update
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VEHICLE SAFETY RATINGS ESTIMATED FROM POLICE REPORTED CRASH DATA: 2007 UPDATE AUSTRALIAN AND NEW ZEALAND CRASHES DURING 1987-2005 by Stuart Newstead Linda Watson & Max Cameron Report No. 266 June 2007 Project Sponsored By ii MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE REPORT DOCUMENTATION PAGE Report No. Report Date ISBN Pages 266 June 2007 0 7326 2336 7 68 + Appendices Title and sub-title: VEHICLE SAFETY RATINGS ESTIMATED FROM POLICE REPORTED CRASH DATA: 2007 UPDATE AUSTRALIAN AND NEW ZEALAND CRASHES DURING 1987-2005 Author(s) Type of Report & Period Covered Newstead, S.V., Cameron, M.H. and Watson, L.M. Summary Report, 1982-2005 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, Queensland Transport, Royal Automobile Club of Queensland, Royal Automobile Association of South Australia 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 drivers of other vehicles and unprotected road users such as pedestrians, cyclists and motorcyclists. Updated crashworthiness ratings and aggressivity ratings for 1982- 2005 model vehicles were estimated based on data on crashes in Victoria and New South Wales during 1987-2005, in Queensland, Western Australia and New Zealand during 1991-2005 and in South Australia during 1995-2005. This update of the ratings included South Australian crash data for the first time. 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, the 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. In addition to the above factors the aggressivity rating was also adjusted for the type of other road user impacted as this factor was strongly related to injury severity and varied between vehicle models. 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 381 vehicle models classified into 10 market groups. They were sufficiently sensitive that they were able to identify 180 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. Aggressivity rating estimates and their associated confidence limits were obtained for 349 vehicle models and were sufficiently sensitive that they were able to identify 145 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. The relationship between vehicle crashworthiness and the year of manufacture of Australian passenger and light commercial vehicles manufactured from 1964 to 2005 was also investigated. Trends were examined by year of manufacture both for the fleet as a whole and by market group for vehicles manufactured from 1982 to 2005. 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, South Australian Department of Transport, Energy and Infrastructure 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: 2007 UPDATE iii EXECUTIVE SUMMARY This report describes the development of further updated vehicle safety ratings for 1982- 2005 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. The aggressivity rating measure is based on collisions between the vehicle being rated and both other vehicles and unprotected road users. It was first developed and successfully applied in Newstead et al (2005b) and in the most recent ratings of Newstead et al (2006) and has been updated here. 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 1987-2005, from Queensland, Western Australia and New Zealand during 1991-2005 and for the first time from South Australia during 1995-2005. 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 aimed at informing consumers about relative vehicle safety performances as well as encouraging manufacturers to improve vehicle safety. 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 293,505 drivers injured in crashes in Victoria during 1987-2005, in New South Wales during 1987-1998, in South Australia during 1995-2005 and in Queensland, Western Australia and New Zealand during 1991-2005. Crashworthiness injury risk was based on 1,608,956 drivers involved in crashes in New South Wales during 1987-2005, in South Australia during 1995-2005 and Western Australia and Queensland during 1991- 2005 where a vehicle was towed away or someone was injured. 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 non-vehicle related 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. Crashworthiness ratings and their associated confidence limits were calculated for 381 individual vehicle models manufactured between the years 1982-2005. The estimates and their associated confidence limits were sufficiently sensitive that they were able to identify 180 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 10 market groups for presentation of the ratings with average crashworthiness of vehicles in each market group estimated. The measure of aggressivity was calculated for 349 models of Australian and New Zealand passenger vehicles manufactured between the years 1982-2005. The aggressivity ratings estimate the risk of a vehicle driver or unprotected road user impacting with the focus iv MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE vehicle model being killed or admitted to hospital when involved in a crash. The estimates and their associated confidence limits were sufficiently sensitive that they were able to identify 145 vehicle models that have superior or inferior aggressivity characteristics compared with the average aggressivity across all vehicle models in the data. Average aggressivity for vehicles in each of the 10 defined market groups was also estimated. Estimated