Evaluation of the regional traffic enforcement plans; Effects of intensified police surveillance on traffic behaviour and road safety Within the framework of a cooperation agreement with the Public Prosecutor's Office, SWOV Institute for Road Safety Research has evaluated the effectiveness of regional plans for traffic enforcement. These plans contain intensified police surveillance of the five 'spearheads' of road safety policy in the Netherlands: speeding, drink driving, not wearing seatbelts and crash helmets, and red light running. First of all, general road safety developments in the various police regions were examined. This was done by comparing the situation in 1994 and 1995 (i.e. before implementing the plans) and that in 2000 and 2001. It must be concluded that the implementation of the regional plans in 2000/01 has not had clearly positive road safety effects. In the regions that had implemented such a plan, the number of severe road injuries (including fatalities) did not decline more than in the other regions (the control area). If, however, only the development in the number of deaths is examined, it appears that in the regions which had implemented such a plan, there has been about a 10% stronger reduction than in the control area. Although this difference was not (statistically) significant, it can be considered a relevant effect. Next, the amount of surveillance and the effect on traffic behaviour was examined. The implementation of regional traffic enforcement plans has especially lead to a considerable increase in police surveillance of driving speeds. Although not to the same extent, this also applied to seatbelt wearing. Intensifying the surveillance of these two spearheads has lead to significant behavioural changes among Dutch motorists. The average speeds and the number of serious speed offences declined significantly and seatbelt wearing increased considerably in the regions with such a plan. Normally these behavioural changes are accompanied by an improved road safety. This indeed happened in some regions that had implemented an enforcement plan, but not in others. Drink driving enforcement activities also increased by about an estimated 5-10% (for the Netherlands as a whole) as a result of implementing regional plans. However, this did not result in a demonstrable decrease in drink driving, nor in an accompanying reduction of alcohol-related injuries. Little data is available about the enforcement level or the behaviour changes regarding crash helmet wearing and red light running. It is assumed that the increase in enforcement of these spearheads during 2000/01 was limited, and that there was probably a limited influence on the behaviour concerned and the resulting road safety. Based on this traffic enforcement evaluation research and literature study, recommendations for future surveillance for each of the spearheads have been formulated. Speeding enforcement: no statement based on the currently available data is possible about the relative effectiveness of the various instruments. It is worth recommending further research. SWOV recommends, while waiting for the results of such research, an extension of driving speed surveillance especially using static controls with inconspicuous radar cars and so-called segment controls. Drink driving enforcement seems to have got a substantial impulse through the regional plans. However, to have substantial road safety effect, it seems to be important that some of the extra surveillance should be concentrated on the small but dangerous group of serious offenders. Only 0.3% of all drivers and 20% of all offenders have a Blood Alcohol Concentration of 1.3 g/l but these are responsible for 80% of all alcohol-related severe injuries. Seatbelt wearing surveillance seems to be very successful according to the regional traffic enforcement teams. SWOV therefore recommend, in future surveillance, to maintain the average enforcement level of the 1999-2002 period in order to at least stabilize the wearing rate and maybe even increase it. Crash helmet wearing surveillance: it is worth recommending that, in future surveillance of mopedists, one strives to consolidate the level achieved in 2001. A further increase does not seem to be cost-beneficial because the target group is relatively small, the wearing rate in 2001 was high, and the enforcement is very labour intensive. Red light running surveillance is not very labour intensive and is usually combined with driving speed surveillance. Although there is no quantitative data about its road safety effect, it seems that surveillance extension can have a positive effect. This is certainly so if attention is concentrated on crossroads with many crashes and/or red light offences and if the road users are informed via a warning. Finally, SWOV recommends an evaluation of the effectiveness and efficiency of using mobile surveillance with inconspicuous video cars for tracing high-risk traffic behaviour (accident-prone drivers). In addition to making recommendations about surveillance, SWOV also recommends a better inventory of surveillance, behaviour, and crash data. This data is essential to determine properly the effectiveness of road safety measures.