Traffic Calming

Traffic Calming


In 2016 a total of 23,550 pedestrian casualties occurred on UK roads. Of this total, 448 were killed (34 of which were children) and 5,140 were seriously injured (1,253 of which were children). (RRCGB, DfT, 2017)

Reducing vehicle speeds would help to reduce the frequency and severity of these RTIs. This is demonstrated by the well established relationship between speed reduction and RTI reduction – a 1 mph reduction in speed results in an average of 5 per cent reduction in RTIs.

Physical traffic calming measures were found to be most effective at reducing speeds when compared to other interventions, such as standard and variable message signs or education campaigns. Of the different types of physical traffic calming, those involving some form of vertical deflection (e.g. speed humps, bumps or cushions) were the most effective at achieving speed reductions. While the numbers can vary quite considerably, many traffic calming schemes have shown RTI reductions of between 60-80 per cent post implementation.

Studies which compare injury severity with vehicle speed show that RTIs at speeds above 20 mph are more likely to result in severe injuries, rather than slight injuries. Traffic calming schemes have been shown to reduce the severity of injury in the event of a RTI and make it easier for drivers to avoid RTIs.

Urban 20 mph zones have become more popular over the past few decades as evidence for their effectiveness has strengthened. These 20 mph zones have been successful in substantially reducing speeds and RTIs in the areas where they have been applied. In some cases they have reduced child pedestrian RTIs by 70 per cent and cyclist RTIs by 48 per cent.

The main issue associated with implementing traffic calming schemes is their cost, although cost benefit analysis does show that it is possible to achieve payback within a year. In addition to cost, some of the physical measures can also produce noise and/or vibration which make them unpopular with some residents.


  • Date Added: 03 Apr 2012, 08:08 AM
  • Last Update: 12 Jan 2018, 11:42 AM