The effect of market group mix on crash risk in the Australasian light vehicle fleet

Monash University Accident Research Centre - Report #295 [2010]

Authors: Keall, M. D. & Newstead, S.V

Full report in .pdf format [590KB]


The objective of this study was to examine potential crash risk and injury effects of wholesale changes in market preference within the light passenger vehicle fleets of New Zealand, NSW and Victoria Analysis was carried out on the registers of licensed vehicles in these jurisdictions which were linked via licence plate numbers to crash data. This enabled an assessment of the composition of the vehicle fleet to be made as well the estimation of crash involvement rates per licensed vehicle.

The study found important differences between the New Zealand light passenger vehicle fleet and the fleets in NSW and Victoria. The New Zealand fleet, probably influenced by the widespread importation of used cars from Japan , was older on average than the NSW and Victorian fleets, but also had proportionately fewer older vehicles. There were also marked differences in crash patterns, with a much larger proportion of crashes in New Zealand occurring on higher speed limit roads than in either Victoria or NSW. This is likely to be a reflection of substantial differences in driving patterns which may also influence the composition of the vehicle fleet that achieves the lowest crash involvement rates. Passenger vehicle market groups were evaluated in terms of their crash rates per vehicle in the three fleets studied. In New Zealand , large cars were generally found to have lower crash involvement rates, whereas in the Australian states, medium cars were superior in terms of crash involvement.

By modelling crash involvement rates using the available data on the vehicles and their owners, various scenarios were tested that involved shifts in market group preferences in each vehicle fleet. In particular, the effects on crash involvement rates were tested where entire market groups were removed from the vehicle fleet and replaced by market groups with lower crash involvement rates. These cannot be seen as realistic scenarios, but rather as extreme shifts that indicate the direction in which vehicle fleet safety could move, given shifts in market group preference. These extreme shifts from large cars to medium cars were predicted to result in as much as a 10% injury crash involvement rate decrease for Victoria and a 5% reduction in tow-away crash involvement in NSW. For New Zealand an overall switch from medium, small and light cars to large cars was predicted to yield an almost 4% decrease in injury crash involvement. Purely lowering the average aggressivity of the fleets by switching from large cars to medium cars was predicted to yield only a very modest reduction in road injury.

Sponsoring Organisations - This project was funded as contract research by the following organisations: Road Traffic Authority of NSW, Royal Automobile Club of Victoria Ltd, NRMA Motoring and Services, VicRoads, Royal Automobile Club of Western Australia Ltd, Transport Accident Commission, New Zealand Transport Agency, the New Zealand Automobile Association, Queensland Transport, Royal Automobile Club of Queensland, and by grants from the Australian Government Department of Transport, Infrastructure, Regional Development and Local Government and the Road Safety Council of Western Australia