This report describes the development of further updated vehicle secondary safety ratings for 1982-2013 model vehicles. The ratings produced cover vehicle crashworthiness, aggressivity and total secondary safety. 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 including pedestrians, bicyclists and motorcyclists. The total secondary safety index measure integrates into one measure the combined crashworthiness and aggressivity performance of a vehicle in a way most representative of the crash population involving the vehicle fleet being rated. It considers relative injury outcomes in the full range of crashes involving light passenger vehicles including single and multi-vehicle crashes, crashes with heavy vehicle and crashes involving unprotected road users. All three measures of vehicle secondary safety performance are estimated from data on real crashes reported to police. The update is based on crash data from Victoria and New South Wales during 1987-2013, from Queensland during 1991-2012, Western Australia and New Zealand during 1991-2013 and from South Australia during 1995-2013. Each of the 3 ratings sets was 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). As far as possible, each index reflects the secondary safety performance related to vehicle design alone by controlling for a range of non-vehicle related factors known to affect injury outcome. Non-vehicle related factors considered were the sex and age of the person whose injury outcome was being measured, speed limit at the crash location, number of vehicles involved, the jurisdiction in which the crash occurred and the year in which the crash occurred. For each measure these factors were strongly related to injury risk and/or severity. In addition to the above factors the total secondary safety rating was also adjusted for the type of crash and road user combination. 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 585 individual vehicle models manufactured between the years 1982-2013. 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 516 models of Australian and New Zealand passenger vehicles manufactured between the years 1982-2013. The 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. Average aggressivity for vehicles in each of the 10 defined market groups was also estimated. Estimated vehicle aggressivity towards drivers of other vehicles or unprotected road users was found to have little or no relationship with ratings of vehicle crashworthiness, demonstrating the independence of the two complementary measures. The total secondary safety index measures the average risk of death or serious injury to all light passenger vehicle drivers and unprotected road users (pedestrians, cyclists and motorcyclists) when involved in a crash with the rated light passenger vehicle to a degree of accuracy represented by the confidence limits of the index in each case. It is a measure of the combined crashworthiness and aggressivity performance of the rated vehicle. Total secondary safety index estimates and their associated confidence limits were obtained for 646 vehicle models classified into 10 market groups. Estimated total secondary safety was found to have a stronger relationship with ratings of vehicle crashworthiness than with vehicle aggressivity. This reflects that crashworthiness is relevant to the injury outcome of road users in a wider range of crash types than are covered by the aggressivity ratings. The index serves as a valuable summary of overall secondary safety of light passenger vehicles both for consumer information as well as for regulators and vehicle safety advocates in identifying and promoting vehicle safety characteristics that optimise overall secondary safety characteristics. For each type of rating estimated, the expanded data set has been able to produce more upto-date and reliable estimates for individual car models than those published previously. A method of presenting the ratings for consumer information is described. The new rating presentation classifies vehicles according to where their rating lies in relation to a best performance benchmark. The crashworthiness of passenger vehicles in the Australian vehicle fleet (cars, station wagons, four wheel drives and vans), has been estimated by year of manufacture for the years 1964 to 2013. This study further updates the original one by Cameron et al (1994a) for years of manufacture 1964 to 1992. Updated trends in Australian crashworthiness by year of manufacture show similar patterns as previously obtained with the greatest gains over the years 1970 to 1979 in which a number of new Australian Design Rules aimed at occupant protection took effect. Further significant gains in crashworthiness have also been observed over the years 1986 to 2012, with notable steady gains from 1985 to 1995 and since 2000. Trends in crashworthiness by year of vehicle manufacture from 1982 to 2013 for each of the 10 vehicle market groups were also estimated showing differential improvement in crashworthiness by market group by year of manufacture. The results and conclusions are based on a number of assumptions and warrant a number of qualifications that should be noted. (Author/publisher)
Samenvatting