Automatic speed management in The Netherlands. [Paper presented at the 75th Annual Meeting of the Transportation Research Board TRB, Washington, D.C., January 7-11, 1996.]

Speed warning and enforcement can be applied locally, on a road-stretch and on a road-network. Local automatic speed warning at an urban intersection reduced the mean speed by 5 km/h. Theoretically a reduction in accidents of 25-65% can be achieved. At a rural intersection, the speed limit was reduced from 100 to 70 km/h. An automatic sign warns speeding cars; this resulted in a lowering of the mean speed from around 80 to 63 km/h. An automatic speed warning and enforcement system on 2-lane rural road stretches - speed limit 80 km/h - resulted in a reduction of the mean speed from 78 to 73 km/h, the percentage of speeders went down from 40 to 10%. The total number of accidents was reduced by 35%. This effect was almost the same, 3 years after concluding the experiment. Vandalism was a problem. This could be diminished by mounting the camera on a high pole, mechanically preventing climbing the pole, automatic detection of vandalism and wireless communication to a near-by police station. Enforcement of speed on a provincial road network using radar and camera exclusively, from a parked unmarked car, was conducted in three provinces. A sign, downstream of the enforcement site, shows `Your speed has been checked. Police'. Periodical information campaigns were conducted to increase the subjective risk of being caught. The result was a reduction of average speed by 4-5 km/h, though the percentage of speeders is still high: reduction from 40 to 30%. This type of enforcement is accepted by 75% of the drivers. Greater priority for speed enforcement is needed, also automating the enforcement and processing to increase the efficiency