Safe speeds

Changes to speed limits

We're lowering speed limits on more routes where there's a higher risk of someone being killed or seriously injured. This follows our implementation of a 20mph speed limit on red routes within the Congestion Charging Zone in central London.

The work is part of the Mayor's Vision Zero policy which aims to see no one killed or seriously injured on our roads by 2041.

These roads had their speed limits reduced on 31 March 2022:

  • A10 Great Cambridge Road between the Great Cambridge roundabout and White Hart Lane will be reduced from 40mph to 30mph
  • A23 in Croydon from the junction with Green Lane to the junction with Alma Place will be reduced from 30mph to 20mph
  • A10 High Road from the Bruce Grove junction with The Avenue to Olinda Road, including A503 Monument Way from the A10 to the Ferry Lane junction, will be reduced from 30mph to 20mph 
  • A107 Clapham Common from the junction with the A10 past Homerton High Street, which is already a 20mph zone, to the junction of the A102 Kenworthy Road with B113 Wick Road will be reduced from 30mph to 20mph
  • A13 Commercial Road between Whitechapel High Street to Butcher Row will be reduced from 30mph to 20mph
  • 12.8km of red routes we manage in Westminster. These roads include, but are not limited to: A501 Marylebone Road, A41 Park Road - St Johns Wood Road, A5 Edgware Road, A4 Knightsbridge, A202 Vauxhall Bridge Road, A302 Grosvenor Place and A4202 Park Lane

Find out more and comment on our plans on the Lowering Speed Limits page on Have Your Say.

 The minimum penalty for speeding in this section will be a £100 fine and 3 penalty points added to your licence.

The Metropolitan Police enforce all speed limits in London. They do this using on-street officers, mobile speed cameras and fixed speed cameras. In 2018, 154,785 people were caught and penalised for speeding-related offences, including 38,878 on 20mph limit roads.

TfL road with 20mph speed limit

Learning from collision data

We're lowering speeds in London for a reason. Collision data from around the world is very clear. It shows that the faster a vehicle is travelling:

  • The more likely a collision will occur because the driver has less time to react, stop or avoid the collision
  • The more severe an injury resulting from the collision will be

For example, if you hit someone at 30mph they're five times more likely to die than if you hit them at 20mph. That's why this new limit is so important and why we ask for you as a driver to watch your speed as you're driving through central London.

Diagram shows increased vehicle speed from 20mph to 30mph results in five times more fatal injuries

Read tips on how to drive safely in London.

Lowering speeds with self-enforcing speed limits

There are many different ways to encourage people to drive at lower speeds, but evidence shows that self-enforcing speed limits are the most successful way to reduce speeds.

A self-enforcing speed limit means that people are more likely to drive within the signed speed limit because they feel it's the easiest and safest speed to drive along that road. This is generally because of the way the road looks and has been designed.

Some of the design and engineering measures used to lower speeds are:

  • Signs
  • Road markings
  • Speed cushions
  • Speed bumps
  • Raising pedestrian crossings
  • Widening footways for people walking
  • Giving more space to people cycling
  • Removing the white line in the centre of a road
  • Changing the surface of the road
  • Creating curves along the road that requires vehicles travelling in different directions have to slow down or give way
  • Introducing more traffic islands in the centre of the road
  • Placing trees, planters and parklets along the roadside or in the centre of the road

There's no 'one size fits all' approach to reducing vehicle speeds. We use different measures depending on the type of road, who uses the road and the road space available.

We'll continue to monitor the effectiveness of these measures in lowering speeds, so we can determine if more design changes are needed.

Effect on traffic and pollution

Imperial University's evaluation of 20mph zones in London shows they have no net negative impact on exhaust emissions.

It also shows that in 20mph zones vehicles move more smoothly, with fewer accelerations and decelerations, than in 30mph zones. This smoother driving style actually reduces particulate emissions from tyre and brake wear.

We closely monitor changes we make to our roads. This may include looking at possible effects on nearby roads as needed. You can see more of our work and research to into reducing road danger on the Road danger reduction page in Publications & reports.

Achieving lower speeds: the toolkit

We've published a toolkit outlining the various speed reduction measures that can be used when designing streets in London.

It can be used by anyone seeking to make our streets safer, healthier and more attractive for walking and cycling. However, it will be of particular relevance to those responsible for implementing specific speed reduction programmes on the Transport for London (TfL) Road Network and local roads managed by the London boroughs.