The International Transport Forum (ITF) has released a study that examined changes in road safety performance in 10 countries that made amendments to speed limits or introduced automatic speed cameras on a large scale. It found a strong relationship between speed and the number of crashes in every case.
An increase in mean speed was accompanied by a higher number of crashes and casualties. A decrease was associated with fewer crashes and casualties. In no case did an increase in mean speed coincide with fewer crashes or casualties.
The ITF says the results confirm existing scientific evidence that speed has a direct influence on the occurrence of traffic crashes and on their severity. According to a widely used scientific formula, every 1% increase in average speed results in a 2% increase in all injury crashes, a 3% rise in fatal and severe crashes and 4% more fatal crashes. Thus, reducing speed by a few kilometres per hour can greatly reduce the risks of and severity of crashes.
The report makes several recommendations. These include reducing the speed on roads as well as speed differences between vehicles; setting speed limits based on the Safe System principles, that is, at a level that humans can survive without dramatic consequences in case of a crash; introducing compensation measures where speed limits are increased, for instance, stricter enforcement or a safety upgrade of the road infrastructure; and using automatic speed control to effectively reduce speed.
Working towards a Safe System, the authors propose as reasonable speed limits: 30km/h in built-up and residential urban areas where motorised vehicles and vulnerable road users share the same space; 50km/h in other urban areas with intersections and high risk of side collisions; and 70km/h on rural roads without a median barrier and a risk of head-on collisions.
The report notes that lower driving speeds generally improve citizens’ quality of life, especially in urban areas. They also reduce emissions, fuel consumption and noise.
You can download the free report here.
