REDUCING THE RISKS

This article assesses the relation between British urban road accidents and vehicle speeds, and discusses whether urban speed limits are too high. Although less than 5% of these accidents are officially due to 'excess vehicle speed', accident statistics indicate that most drivers involved in accidents travel within 10% to 15% of the indicated speed limit. The author suggests speed limits appropriate for various types of road, in the light of injury causation mechanisms, especially for urban areas, where many vulnerable road users are at risk. In collisons between cars and pedestrians, a pedestrian's chance of being killed rises dramatically with increase in car speed. A reduction of motor traffic speeds to 20 mph would reduce the levels of pedestrian injuries in collisions, and give both pedestrians and cars a better chance of avoiding a collision. Accident analysis shows two types of accidents that can be treated by various speed reduction techniques: (1) accidents to single vehicles driving fast and 'out of control'; (2) accidents to vulnerable road users especially pedestrians, cyclists and children. Experience in The Netherlands, Germany and Denmark indicates that accidents can be reduced by 15% to 40% within an area treated by traffic calming and speed reduction. Several examples of the effects of these measures are given. The author advocates similar calming measures for the UK and estimates their possible costs. (TRRL) (Author/TRRL)