In this report the results are presented of two studies which were carried out in the framework of the project on selective traffic law enforcement of speeding behavior. The first study was designed to determine the influence of the intensity in a given time period of speeding directed police surveillance procedures. On two roads, an experimental and a control road, continuous registrations of driver speeds were obtained. Firstly, intensified speeding directed surveillance procedures were performed on the experimental road during a period of two weeks. These procedures were radar control and obtrusive stopping of speeders, placing of an unmanned obtrusive police car alongside the road and motor surveillance. This procedure led to clear-cut effects at both measurment sites on the experimental road in terms of the reduction of the mean speed. Secondly, during a period of three weeks the level of intensified enforcement was reduced to about half the previous level. The second study concerned the determination of the effectiveness of daily posted feedback of the percentage of cars not exceeding 95 kmh on roads with a speed limit of 80 kmh. Posted feedback combined with half intensified surveillance led to greater reductions of the mean speed than were previously found using intensified surveillance. An opinion survey led to the conclusion that road users could clearly perceive these speed reductions. However, the majority of road users claimed not to have changed their speed choice on the basis of the posted feedback procedure. The possibilities of using posted feedback about speeding behavior need to be studied in more detail.
Abstract