In the period from September 1999 till March 2000, SWOV conducted a roadside survey in 10 Dutch police regions in order to establish the motorists' alcohol consumption. In the regions involved, special traffic enforcement units were formed, aimed at intensifying the enforcement of, among other things, drinking and driving laws. The enhanced enforcement effects will be evaluated by means of a pre- and post-test with control group, consisting of motorists in the 15 police regions without a special traffic police unit. In these control areas, SWOV also conducted a roadside survey. The roadside surveys of the pre-test were carried out in close collaboration with the Ministry of Transport and the police. In the experimental area, a random sample of 16,020 motorists were breath tested for alcohol by the police; in the control area, the sample comprised 13,359 motorists. All motorists were tested in Friday and Saturday nights, between 10 pm and 4 am. Some results of the pre-test are: In the experimental group, 4.0% of the motorists tested had an illegal blood alcohol content (BAC more than 0.5 g/l), versus 4.4% in the control group; Nationwide, the weighted share of illegal BAC's was 4.3%. This figure indicates a stabilisation of drink-driving in the Netherlands, compared with the illegal BAC shares for 1997 and 1998; Drink-driving by young male motorists, aged 18-24, is still developing in an unfavourable way: 3.1% illegal BAC's in 1991-1993, 3.5% in 1994-1996, and 4.0% in 1997-1999; and the majority (55%) of motorists with an illegal BAC came from a public drinking place. Recommendations are made for the organisation of police enforcement. For example, in order to ensure cost-effectiveness of the enhanced police enforcement, it is important that it will be concentrated at days and times of day with relatively high numbers of drinking drivers.
Abstract