New data shows significant improvements in road safety in London since introduction of 20mph speed limits

13 February 2023
At sites monitored on the Transport for London Road Network (TLRN), collisions involving a vulnerable road user have decreased by 36 per cent, while collisions resulting in death or serious injury have decreased by 25 per cent after speed limits were lowered
"It's brilliant to see the huge impact the introduction of 20mph speed limits has had on road safety around London. "
Penny Rees
TfL Head of Healthy Streets Investment
  • Lower speed limits play a critical role in the Mayor's Vision Zero plan to eliminate death and serious injury from the transport network     
  • People hit by a vehicle at 20mph are around five times less likely to be killed than at 30mph    

Transport for London (TfL) has released new data that shows a significant reduction in the number of collisions since the implementation of 20mph speed limits on key roads in London. Lowering speed limits is a key part of the Mayor's Vision Zero goal to eliminate death and serious injury from London's transport network and to enable more walking and cycling in the capital.    

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), demonstrating the huge impact of lowering speeds across London. 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 110km is on TfL's network. TfL is now working to lower speeds on 220km of its roads by 2024 in inner and outer London and plans to introduce a new 20mph speed limit on over 28km of roads in Camden, Islington, Hackney, Tower Hamlets and Haringey in March.    

Collision data from around the world shows that the speed at which people are driving or riding is the single most important factor in whether a collision takes place and how severely people are injured. In 2020, 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 new speed limits have also made a large portion of London safer for people to live, work and commute, encouraging more Londoners out of their cars to walk, cycle and use public transport. More people now use healthier and more sustainable forms of travel which is vital to reducing congestion and air pollution.    

TfL is working with the Met Police to increase their capacity to take enforcement action against drivers and riders who speed. They are currently on target to be able to take action on a million speeding offences by 2024.  In 2021/22, the Met enforced 476,685 speeding offences, an increase of 72 per cent compared to the previous year.       

Will Norman, London's Walking & Cycling Commissioner, said: "I'm delighted to see that the introduction of 20mph speed limits is having such a positive impact on the number of collisions on London's roads; this forms an important part of the Mayor's Vision Zero plan. I look forward to the continued expansion of this programme on TfL roads and to working with colleagues in boroughs to make even more streets safer for Londoners. 

"Sadly more than 4,000 people are killed and seriously injured on London's roads every year. Lowering speeds is one of the most important things we can do to reduce road danger and make it easier and safer for people to walk, cycle and use public transport, creating a safer, greener London for everyone." 

Penny Rees, TfL Head of Healthy Streets Investment, said: "It's brilliant to see the huge impact the introduction of 20mph speed limits has had on road safety around London. We are determined to eliminate deaths and serious injuries from London's roads in line with our Vision Zero goal, and this data proves that lowering speeds is crucial to achieving this goal. 20mph speed limits not only save lives, but also encourage Londoners to travel in more active and sustainable ways. We look forward to seeing the expansion of the programme benefit more areas of London."    

Jeremy Leach, London Campaign Co-ordinator for 20's Plenty for Us said: "This research underlines once again the importance of reducing vehicle speeds to a maximum of 20mph in built-up areas. Injuries are reduced and more people can feel safe to walk and cycle. TfL is right to be rolling out more 20mph limits on the roads that it manages and to be calling for the default speed limit on all residential roads in London to be changed to 20mph."  

Scott Williams, Head of Programme Delivery at Brake, the road safety charity, said: "We have long supported the call for 20mph speed limits in places where motorised traffic is in close proximity to people walking and cycling. We are encouraged by the reduction in collision numbers, including those involving the most vulnerable road users, following the introduction of the 20mph schemes. We believe that everyone has the right to make safe and healthy journeys, every day, whoever they are and however they travel, and we know that slow traffic is fundamental to this - saving lives and creating happier and healthier communities."