Trends in crashworthiness of the New Zealand vehicle fleet by year of manufacture: 1964 to 2002

Monash University Accident Research Centre - Report #238 [2005]

Authors: Newstead, S.V. & Watson, L.M

Full report in .pdf format [450KB]


Crashworthiness is an estimate of the occupant protection provided by a vehicle, namely the risk of a driver of a vehicle being killed or admitted to hospital when involved in a crash. The relationship was investigated between vehicle crashworthiness and both the year of manufacture and the year of first registration (in New Zealand) of New Zealand light passenger vehicles manufactured from 1964 to 2002 and crashing during 1991 to 2002. The latter analysis was aimed at assessing crashworthiness trends in the fleet of used imported vehicles in New Zealand whilst the former examined trends in the fleet as a whole. Crashworthiness was measured by a combination of injury severity (of injured drivers) and injury risk (of drivers involved in crashes). The ratings were adjusted for the sex and age of the driver, the speed limit at the crash location, the number of vehicles involved in the crash and the year in which the crash occurred. The crashworthiness rating estimates the risk of the driver 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.

Analysis of trends by year of vehicle manufacture showed statistically significant improvement in the crashworthiness of New Zealand light passenger vehicles over the years of manufacture studied. Most of the measured improvement occurred over the years of manufacture from 1983 to 2002. Over this period, the risk of death or serious injury to drivers reduced by around 50% for the fleet as a whole. During this period vehicle safety in New Zealand was affected by several competing effects: a general increase in both active and passive safety features in vehicles; increasing proportions of used imported vehicles entering the New Zealand fleet; and increases in the regulation of vehicle safety standards by the New Zealand Government.

Both the level of absolute crashworthiness and trends on a year of manufacture basis were similar for used imports to those for vehicles sold new in New Zealand. Estimates of crashworthiness trends in the used import vehicle fleet by year of first registration in New Zealand from 1978 to 1998 showed statistically significant improvements in crashworthiness over these years. Absolute levels of crashworthiness and improvements by year of first registration paralleled those seen in the analysis by year of manufacture but occurred some 6 years later, a lag equivalent to the average age of the used imported vehicles over the study period .

Sponsoring organisation - Land Transport New Zealand (previously the Land Transport Safety Authority, LTSA)