Crashworthiness ratings measure the relative safety of vehicles in preventing severe injury to their own road
users in crashes whilst aggressivity ratings measure the serious injury risk vehicles pose to other road users
with which they collide. A total secondary safety index was successfully developed which summarises the
combined crashworthiness and aggressivity performance of a vehicle, weighted by the relative importance of
each component in real world crash circumstances, into a single integrated measure. The index estimates the
risk of death or serious injury to light vehicle drivers and unprotected road users in the full range of crash types
involving light passenger vehicles
The total secondary safety index developed has been estimated for 1982-2004 model vehicles were based on
data from crashes reported to police in Victoria and New South Wales during 1987-2004 and in Queensland,
Western Australia and New Zealand during 1991-2004. Total secondary safety 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). The index was 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, 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 this rating was also adjusted for the type of crash
configuration as this factor was strongly related to injury risk and/or severity. The degree of accuracy of the
index is represented by a confidence limit on the index.
Total secondary safety index estimates and their associated confidence limits were obtained for 357 vehicle
models classified into 12 market groups. They were sufficiently sensitive that they were able to identify 139
models of passenger cars, four-wheel drive vehicles, passenger vans and light commercial vehicles that have
superior or inferior total secondary safety characteristics compared with the average vehicle.