Citation

Hauer E, Cooper PJ. Transp. Res. Rec. 1977; 643: 18-22.

Copyright

(Copyright © 1977, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The enforcement of traffic laws is based on the belief that it induces greater driver compliance with the rules of the road, which leads to a reduction in the number of accidents. Conclusive empirical evidence substantiating this belief has, however, not previously been presented. The availability of computerized accident records for the Metropolitan Toronto Police Selective Enforcement program provided a unique opportunity to test whether increased enforcement was followed by a reduction in the number of accidents. By using accident records for 1800 locations over a period of 4 years, estimates of accident rates were obtained that accounted for a time trend and seasonal variations. The expected number of accidents so obtained was compared to the number of recorded accidents. Locations that received increased enforcement showed consistently fewer than the expected number of accidents. In the experiment, all important factors except increase in enforcement are randomized. Thus, unless there is some undetected causal factor, the reduction in accidents is statistically significant and can be attributed to the increased enforcement. If then, selective enforcement leads to a reduction in accidents, enforcement of traffic laws in general has the potential to reduce accidents. Therefore, it is important to deploy available enforcement resources to maximize their effect.