20mph Zones and Speed Limits Facts

15 June 2020

In 2018, 806 people were killed, 17,839 were seriously injured, and 98,000 were slightly injured in reported road collisions on built up* roads in Great Britain . A large proportion of these accidents occurred on residential roads, with 108 deaths on B roads in built-up areas and 316 deaths on other minor roads in built-up areas.

Speed significantly increases the chance of being injured in a collision. Further science-based information is available on The Road Safety Observatory.

Research has shown that the risk of death for pedestrians struck by cars increases at higher impact speeds, although the exact risk levels varied between the studies.

One of the first studies of pedestrian injury and car impact speed found that at 20mph there was a 2.5% chance of being fatally injured, compared to a 20% chance at 30mph, although this study is now regarded as having overestimated the risks. A recent review identified the studies which had produced the most reliable modern estimates.

 A new 20mph Zones and Speed Limits Factsheet now available from RoSPA adds more readily available knowledge.