Effect of Speed limits on speed and safety: A review

This paper draws on the results of studies conducted around the world on the effect of speed limits on speed and safety. It is observed that, generally, motorists do not adhere to speed limits but instead choose speeds they perceive as acceptably safe. Perceptions of safety are influenced by the environment in which travel takes place such as whether the road is a controlled access facility, the nature of adjoining land use, the geometry of the road and existing weather conditions. The relationship between speed and safety is influenced by factors such as the type of road, driver age and vehicle safety devices. Research shows that speed cannot be linked statistically to the incidence of accidents, although it is statistically significant in accident severity. If speed limits are increased only on controlled-access facilities, while retaining lower speed limits on other facilities, system-wide safety may not be adversely affected. The main benefits of increasing speed limits seem to be in improving their credibility with the public and regaining control of speed behaviour on highways.