Improve road safety
Speed influences both the likelihood that a crash will occur on any given road, and the severity of the crash. In general, every 1mph reduction in average is accompanied by a 5% reduction in the number of crashes. Casualty severity is very sensitive to impact speed. Even minor reductions in speed can make the difference between a crash being fatal or serious, and between serious and slight. This relationship is especially important where pedestrians and cyclists are present.
Excessive speed is the single most important contributory factor in road deaths. Drivers who speed are known to be more likely to crash.
Speed is the one common factor in crashes which is most amenable to intervention, through traffic calming, speed limit reductions and enforcement.
The Transport Research Laboratory have estimated that reducing average speeds across the entire road network by only 2mph would save an estimated 280 lives a year, prevent 3900 serious injuries and reduce all crashes involving injury by 24,000. These figures are approximately 10% of the annual casualties on our roads.