This before and after study describes an experiment with a combined use of police enforcement and publicity on drinking and driving. This experiment was conducted in the Leyden subregion in October 1988 - October 1989. The aim was to reduce the proportion of drivers while under the influence of alcohol in week-end nights by at least one fourth. The experimental design was mainly based on a deterrence model. The magnitude of the risk of being caught, the punishment certainty, and the penalty promptness are factors that play a more important role within this model than does the punishment severity. In the course of the experiment, the percentage of drivers with a blood alcohol content (BAC) of 0.5 promille or more during weekend-nights decreased from 8.1% in October 1988 to 6% in October 1989. This decrease was already realized in April 1989. No important changes in driving while under the influence of alcohol (DWI) took place in the second half year of the experiment. The decrease in DWI occurred almost exclusively in the group of car drivers with a BAC between 0.5 and 0.8 promille. The most important conclusion of the experiment is that an increase of the effectiveness of police enforcement can have a positive influence on DWI.
Samenvatting