This study describes the calculation of updated vehicle safety ratings that measure the relative safety of vehicles in preventing severe injury to people involved in crashes. Three different aspects of secondary safety are examined: crashworthiness which focuses on drivers of the rated vehicle, aggressivity which focuses on drivers of other vehicles and unprotected road users such as pedestrians, cyclists and motorcyclists colliding with the rated vehicle and total secondary safety which examines the combined crashworthiness and aggressivity performance of the rated vehicle. Updated ratings for 1982-2007 model vehicles were estimated based on data on crashes in Victoria and New South Wales during 1987-2007, in Queensland, Western Australia and New Zealand during 1991-2007 and in South Australia during 1995-2007. Each rating is measured as 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, crash configuration and type or road user 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. A new method of presenting the ratings for consumer information is introduced. The new rating presentation classifies vehicles according to where their rating lies in relation to a best performance benchmark. Crashworthiness estimates and their associated confidence limits were obtained for 427 vehicle models classified into 10 market groups with 203 models of vehicles identified as having ratings of adequate statistical precision to be compared to the crashworthiness benchmark rating of 1.60%. Aggressivity rating estimates and their associated confidence limits were obtained for 397 vehicle models with 154 having ratings of sufficient statistical precision to be compared to the aggressivity benchmark rating of 1.93%. The total secondary safety index estimates and their associated confidence limits were obtained for 484 vehicle models classified into 10 market groups with 239 being of sufficient statistical precision to be compared to the total safety index benchmark index of 1.91%. The relationship between vehicle crashworthiness and the year of manufacture of Australian passenger and light commercial vehicles manufactured from 1964 to 2007 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 2007. The results of this report are based on a number of assumptions and warrant a number of qualifications that should be noted. (Author/publisher)
Samenvatting