From 2 March 2020, the roads we operate and manage within the central London Congestion Charging Zone will have a new speed limit of 20mph. Some of these have an existing speed limit of 20 mph, however 19 of 37 of these will be new.
Collision data from around the world is very clear. It shows that the faster a vehicle is travelling:
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.
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.
The Metropolitan Police will continue enforcing all speed limits across London, including where new speed limits are in place.
The second phase will look at a further 140 kilometres of our road network in inner and outer London, including on the inner ring road, high-risk roads and roads in town centres.
We've completed a risk analysis to identify roads in inner and outer London where speeds should be lowered to reduce the risk of road users being killed and seriously injured, focusing on town centres and roads with the highest risk of a collision occurring.
The risk analysis considers:
This might mean speeds will be lowered along some roads from 50mph to 40mph, or from 40mph to 30mph.
We'll be engaging with local communities and road users about how we introduce these limits as we lower speeds across the city.
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:
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.
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 Safety Publications and Reports page.
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.