Speed is a major contributory factor in accidents. Several studies indicate that speed is a contributing factor in about 30% of all accidents. It is however not so easy to make firm statements on simple accident causes, because in a majority of accidents more factors are involved. Drivers driving above existing speed limits are using 'excess' speeds. Excess speeds are strongly related to accident risk. However, drivers driving below a speed limit may still drive too fast for the conditions. Such drivers drive at 'inappropriate speeds'. By definition these inappropriate speeds correlate perfectly with accident risks and it is to be preferred to work with inappropriate speeds. A safe speed can be a speed below an existing limit. But in practice it is hardly possible to establish which speed is appropriate and which speed has to be considered as inappropriate. Excess speed is used almost always in speed policies and in related research for practical reasons. A lot of literature is available on the speed problem. (Author/publisher)
Abstract