20mph limits in London helping to reduce collisions

  • February 15, 2023

Transport for London (TfL) has released new data that show a significant reduction in the number of collisions since the implementation of 20mph speed limits on key roads.  

Monitoring of the 20mph schemes in London shows that, since they were introduced, the number of collisions has reduced by 25 per cent (from 406 to 304), and collisions resulting in death or serious injury have reduced by 25 per cent (from 94 to 71). Vulnerable road users continue to be most at risk on London’s roads but, since the 20mph speed limits have been introduced, collisions involving vulnerable road users have decreased by 36 per cent (from 453 to 290), while collisions involving people walking have decreased by 63 per cent (from 124 to 46). 

In March 2020, TfL introduced a 20mph speed limit on all of its roads within the central London Congestion Charging zone as part of its Vision Zero commitment to eliminate death and serious injury on the capital’s roads by 2041.  Currently over half of London’s roads have a 20mph speed limit, of which almost 110 km are on TfL’s network.  

In 2020, TfL says speed was a contributing factor to 48 per cent of fatal collisions. Since the 20mph speed limits have been introduced across London, there have been reductions of 1.7-5mph across most sites surveyed. Analysis of journey times, traffic flows and speeds suggest that the 20mph speed limit has not increased congestion and TfL will be undertaking further quantitative analysis to assess the impact on smoothing traffic flows. 

The London figures follow the publication last month of positive new data for Brussels, which now applies 30 km/h limits on almost all streets.