Trends in the safety of the New Zealand vehicle fleet: 1964 to 2021. Supplement to MUARC Report 367 - vehicle safety ratings estimated from police-reported crash data: 2023 update.
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. This project further investigated the relationship between vehicle crashworthiness and both the year of manufacture and the year of first registration in New Zealand. Analysis was based on New Zealand light passenger vehicles manufactured from 1964 to 2021 and crashing during 1991 to 2021. Analysis by year of first registration in New Zealand was aimed at assessing crashworthiness trends in the fleet of used imported vehicles in New Zealand whilst analysis by year of manufacture 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. The most rapid improvement (70%) occurred over the years of manufacture from 1983 to 2007. 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. Over the period 2007 to 2021, the risk of death or serious injury to drivers reduced by a further 53% for the fleet as a whole. Estimates of crashworthiness trends in the used import vehicle fleet by year of first registration in New Zealand from 1986 to 2021 showed improved crashworthiness of the used import fleet over these years. A differential in apparent safety between the new and used imported vehicles was identified along with a trend to improving crashworthiness for new vehicles sold in recent years.
This report also presents the updated Used Car Safety Ratings (UCSR) that measure the relative safety of vehicles in preventing severe injury to people involved in crashes. Where a particular vehicle is not sufficiently common in the Australasian light vehicle fleets, the Vehicle Safety Risk Rating (VSRR) shows the likely safety level of the vehicle based on similar vehicles but produced at a more aggregated level than the UCSR. The VSRR applies to specific market groups (e.g., small cars) for each year of manufacture. For a very small proportion of vehicles, the average rating for a given year of manufacture across all market groups is the best safety rating available as information regarding the market group of the vehicles is lacking.
The results of this report are based on a number of assumptions and warrant a number of qualifications that should be noted.
