Mandatory vehicle inspections – are they worth it?
New research which weighed the safety benefits of periodic vehicle inspections against the expense to motorists found that very frequent inspections don't prevent enough crashes to justify the costs.
Researchers at the Monash University Accident Research Centre (MUARC), a Centre within the Monash Injury Research Institute, compared the schemes, which identify and remove defective vehicles from the road, in New Zealand and Victoria, Australia.
The New Zealand Warrant of Fitness (WoF) scheme requires motorists to obtain an inspection annually for cars up to six years old and every six months for older vehicles. The inspection checks for structural and mechanical defects that can impact on safety.
In Victoria, a Roadworthy Certificate must be obtained whenever a car is sold or if a used vehicle needs to be reregistered. In addition, police may issue a defect notice requiring the motorist to fix identified problems and obtain a Roadworthy Certificate.
The New Zealand WoF scheme is relatively expensive with six monthly inspections estimated to cost NZ motorists an additional $250 million annually compared to yearly inspections.
MUARC's Associate Professor Stuart Newstead led the research.
“For twice annual WoF inspections to be cost-effective compared to annual inspections, the increased inspection frequency would need to result in at least a 12 per cent reduction in injury crashes,” Associate Professor Newstead said.
“Analysis of the WoF inspection data showed that the average number of defects detected per vehicle was very small for new vehicles but grew steadily as the vehicle aged. Increasing the frequency of the WoF from once to twice yearly reduced the number of defects detected per inspection by 13.5 per cent."
"However, analysis in both this study and results from other research showed the reduction in crash risk from doubling the frequency of inspection was likely to be significantly less than the 12 per cent required to make six-monthly inspections cost effective,” he said.
The Victorian analysis is not entirely conclusive; however, it suggested the maximum annual crash savings that could be achieved through introducing an annual vehicle roadworthiness inspection for vehicles over five years old would be around 4 per cent. This is likely to be much less than required to make an annual inspection scheme cost effective.
“There are definite safety benefits to having periodic vehicle inspections, but our analysis shows that the benefits are at best modest and that the costs of implementing these schemes are likely to far outweigh any benefit to the community,” Associate Professor Newstead said.