alt-text Lambeth has introduced a borough-wide 20mph speed limit across Lambeth from April 2016 onwards.

By reducing speeds to 20mph, it will reduce the number of casualties in the borough, improve pedestrian safety, encourage more confidence among cyclists and cut the number of incidents around schools.

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1. Summary

Lambeth has introduced a borough-wide 20mph speed limit in Lambeth. Lambeth Council is committed to making our streets a safe and clean place for everyone. We are taking preliminary steps into making Lambeth a safe haven, not only for its residents but for visitors as well.

As part of the aim to have the safest and greenest streets in the capital, all Lambeth’s roads have been given a 20mph speed limit. Lambeth council are in charge of the majority of roads in the borough, apart from the major routes into and around London, which are controlled by Transport for London.

Driving slower on residential roads has been proven to reduce traffic accidents, making the urban environment safer, not only for drivers but for pedestrians, cyclists and motorcyclists, which make up 80% of serious and fatal collisions.

2. Key benefits

By reducing speeds to 20mph it will reduce the number of casualties in the borough, improve pedestrian safety, encourage more confidence among cyclists and cut the number of incidents around schools.

Main benefits of the roll out include:

  • Health- More people are encouraged to walk and cycle Road safety- Reducing speed reduces the number of severe casualties on the road
  • Cleaner air- The air quality is improved by less carbon emissions from vehicles
  • Safer Communities- creating ‘healthy’ streets where people feel safer to walk, cycle, drive and play.

3. Frequently asked questions

What is the evidence that roads will be safer with 20mph speed limits?

Evidence from several areas across England shows that the implementation of 20mph limits reduces the number and severity of road traffic collisions. The Government has recommended that local authorities consider 20mph speed limits in cities based on this evidence. The severity of injuries sustained in the event of a collision is directly linked to the speed at which vehicles travel. A pedestrian, if struck by a vehicle driving at 20mph, is likely to suffer slight injuries. At 30mph they are likely to be severely hurt and at 40mph or above are likely to be killed. Reducing the speed limit to 20mph will have a direct impact on pedestrian safety and is one of the principal reasons for introducing the scheme throughout the borough. Evidence from other schemes includes:

  • Portsmouth; 20mph limits have lowered casualties in road traffic collisions by a further 8% than may have otherwise occurred
  • Warrington; A reduction in collisions of 25% in 20mph speed limit areas
  • Nottingham; In the Sherwood area of Nottingham, which has had a full year of 20mph on residential roads, average speeds have decreased by 5.2%. Casualties in road traffic collisions have reduced from an average of 9.4 per year before implementation, to 8 (all slight) in the year following implementation.

Will a new speed limit really change drivers’ behaviour?

The introduction of 20mph speed limits is just one element of a package of measures to reduce vehicle speeds. Reducing the speed limit should not be seen as an end in itself, but as part of the wider ‘Do the Right Thing’ campaign to encourage people to create a safer and more pleasant environment in the borough, with the understanding that a default appropriate driving speed of 20mph in residential areas can contribute to such an aim.

Surely journey times will increase due to lower speeds?

Inevitably some journey times for some people will increase slightly, however the disadvantage to drivers is considered to be far outweighed by the road safety benefits. The increase in journey time is expected to be small in reality and by easing traffic flow, 20mph may actually reduce some journey times.

Will there be more congestion on our roads?

On a clear stretch of road, travelling at 20mph will obviously take longer than travelling at a higher speed. However research indicates that at slower speeds vehicles flow more smoothly through junctions. As such, within an urban environment, 20mph may help to improve traffic flow and, as a result of reduced acceleration and braking, 20mph may help to reduce fuel consumption and associated emissions.

Will a 20mph speed limit increase traffic noise?

Driving at 20mph has been found to reduce traffic noise. The benefit of a signs-only scheme is that drivers can adopt a smoother driving style than if they were driving through a calmed zone with humps. A study in Graz, Austria found that the introduction of 30kph (18mph) signs-only limits led to a noise reduction up to 2.5 decibels. Compared to 30mph, 20mph means 3 decibels less traffic noise. This level of noise reduction means that people can more easily listen to each other and also sleep better.

What impact will 20mph limits have on air pollution?

The greatest environmental benefit from the change will come from unlocking the potential for walking or cycling short distances instead of driving. Adopting a smoother driving style can also achieve lower emissions. Generally, driving more slowly at a steady pace saves fuel and carbon dioxide emissions, unless an unnecessarily low gear is used. Along shorter roads with junctions and roundabouts, limiting acceleration up to 20mph reduces fuel consumption.

Will bus journey times increase?

Most bus services travel along roads that will stay at their current speed limit. It is only at the ends of some routes, where the buses go onto residential roads, where the speed limit might be 20mph. Most buses spend very little time travelling at more than 20mph, particularly in residential areas due to the frequency of stops and the need to carefully negotiate obstacles such as parked cars.

Will emergency services be affected?

All speed limits contain an exemption for vehicles on emergency calls, so ambulances using blue lights could travel as quickly as was safe to do so, based on road conditions rather than the speed limit.

What will be the impact on business costs and delivery times?

Evidence from Germany shows that slower limits resulted in 12% less fuel use by vehicles as driving became smoother. The impact of reduced transport costs on business supply chains is significant and will help Lambeth businesses thrive. Journey times may also actually be reduced as traffic moves more smoothly (see comments above), resulting in more efficient deliveries. We plan to work with businesses on the publicity and education campaigns around 20mph areas, looking at both business operations and benefits to the workforce through promotion of walking and cycling and improved road safety.

Aren’t 20mph limits just another way of unfairly targeting motorists?

20mph creates a safer environment for everyone, including motorists. It will not significantly increase journey times and, by easing traffic flow, may actually reduce some journey times. We are not trying to stop people from driving, but are trying to balance the needs of drivers with the safety and environment of local residents. The change can be compared to anti-drink driving campaigns and the Clunk, Click seatbelt campaign: over time it has become unacceptable to drive while drunk and it is now second nature to put a seatbelt on to drive. In reality vehicles are rarely driving at a consistent speed, particularly in a city where there is constant accelerating, decelerating and braking to respond to current traffic speeds, traffic lights or junctions. Speed enforcement is carried out by the Police, in association with the local authorities. The revenue from any fines goes to central Government funds, and to fund speed awareness courses. None of the money from fines goes directly to local authorities.

Will the new speed limits actually be enforced?

We expect that most drivers will comply with the newly introduced speed limits and recognise the benefit in making the borough’s roads safer places to be. The Police support the introduction of 20mph speed limits across the borough in appropriate locations. Where persistent breaches of the speed limit are identified a referral will be made to the local police teams who may choose to deploy community speed watch in that area. Officers can also use powers under the Police Reform Act to warn drivers and seize vehicles from persistent offenders.

How much will it cost?

A £700,000 budget has been made available to introduce the borough-wide 20mph speed limit. This funding comes from Transport for London’s (TfL’s) Local Implementation Plan budget; money allocated by TfL to boroughs to spend on transport projects. The funding will cover site surveys, scheme design, the communications campaign, statutory consultation, new signage and construction.

4. How you can get involved

To become an advocate for the 20mph campaign all you need to do is:

  • Share your personal road incident stories to help others understand the implications of speeding
  • Send in photos of alternative ways you commute to work i.e. cycling
  • Share any road safety initiatives that you spot within your community
  • Send us your views /findings on Twitter using the hashtag #Lambeth20mph

For more information or to discuss the 20mph plans please email us at

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