Introducing 20mph speed limits: frequently asked questions

There is a growing consensus on safe speeds in communities that we can build from. We still believe that 20mph is right, but we want to make sure we are getting the right speeds on the right roads.

Between April and August 2024, Ken Skates MS, Cabinet Secretary met and listened to citizens, bus drivers, emergency services, the police, young people, vulnerable people, businesses, county, town and community councillors, local authorities and many others – to understand their views on road safety in residential areas.

In July 2024, we gave highway authorities revised guidance to make it clearer where roads can be 30mph. In 2024, the public has had a chance to suggest where they feel changes should be made.

Highway authorities are now using our revised guidance to assess these suggestions.

Any change in speed limits will need to be made through a traffic regulation order. This process will take several months to complete.

Not all 30mph roads changed to 20mph in September 2023.

You can see a map on DataMapWales that shows which roads have stayed at 30mph.

In 2024, the public has had a chance to suggest where they feel changes should be made. 

Highway authorities are now using our revised guidance to assess these suggestions.

You can still provide feedback about local authority-managed roads by contacting your local authority directly.

If you are driving in a residential or built-up area, and there are streetlights, then drive at 20mph unless you see a sign telling you otherwise.

See streetlights, think 20mph.

There are gateway speed limit signs, the larger signs shown as you enter a different speed limit area, to clearly indicate the correct speed.

Repeater signs, the small circle signs often seen on streetlights, are no longer allowed on roads where the default speed limit is 20mph. However, since they display the correct speed, highway authorities will have until September 2024 to remove these signs. This also applies to 20mph zone signs outside schools and highway authorities have until 2028 to remove 20mph signs painted onto road surfaces.

In any 20mph areas without streetlights, additional signs are in place to indicate the speed limit.

But in built up areas, see streetlights think 20mph, unless you see a sign that says otherwise.

The latest monitoring report, which brings together the most recent data on traffic speeds, journey times and air quality, was published by Transport for Wales (TfW) in September 2024. 

TfW will continue to monitor the effects of the 20mph limit, with its next report due early in 2025.

GoSafe and police partners are using a combination of engagement and enforcement. 

More information can be found on the GoSafe website.

Welsh Government does not receive any money from speeding fines. As with all speeding fines, any money generated goes to HM Treasury.

Police, fire and ambulance services are allowed by law to exceed speed limits to respond to emergency calls. The introduction of the 20mph default speed limit does not change that and so should not delay their response.

The police believe response times will not be affected and that the roads being slower could make it easier for emergency services to make progress.

So far there's no indication that congestion has increased as a result of the new speed limit

Lower driving speeds should result in lower tyre, road and brake abrasion. Smoother driving, with fewer accelerations and decelerations, generates fewer particulate emissions from tyre and brake-wear. You can read more in this Transport for London report from 2018.

Fuel consumption is mainly influenced by the way we drive – driving at a consistent speed is better than stopping and starting (see NICE Overview | Air pollution: outdoor air quality and health | Guidance | NICE). A default 20 mph limit and a smooth driving style, can help avoid unnecessary speeding up and slowing down, saving fuel.

Accelerating up to 30mph can take twice as much energy as speeding up to 20mph.

Transport for Wales (TfW)  published the 20mph phase 1 air quality monitoring report in May 2024. The data shows no material effect on local air quality to date.

Imperial College London found that 20mph limited areas were “pollution neutral”. Many things contribute to pollution levels. 

They include:

• driving style
• acceleration
• braking
• vehicle condition
• distance travelled
• engine temperature

We believe the lower speed limits may encourage more people to choose active ways to travel and there will be fewer polluting cars on the roads.

The evidence from around the world is very clear – decreasing speeds will reduce collisions, save lives, and reduce injuries – helping to improve quality of life and make our streets and local communities safer for all.

Data published in June 2024 shows reduced casualties on 20/30mph roads since the introduction of 20mph in September 2023. 

We’ll need multiple years’ worth of data to draw firm conclusions, but it’s encouraging to see things moving in the right direction. 

The implementation of the 20mph speed limit has cost around £32 million.

Research undertaken by public health practitioners and Edinburgh Napier University suggests that the estimated reduction in casualties each year from the introduction of the 20mph default speed limit in Wales, could provide around £92m in prevention savings.

This includes, but is not limited to, reduced impact on the NHS and emergency services. Other savings included are human costs and lost output (including future lost earnings). 

It does not include the potential wider health benefits of people walking and cycling more. 

Our assessment shows that reducing speeds to 20mph could result in an average increase of one minute per journey, balanced against saving up to 9 lives and preventing up to 98 serious injuries each year.

Before the law was passed, we produced an impact assessment that considered all the potential estimated costs and benefits. This was included in the explanatory memorandum.

It included the costs of any delays to travel time, including journeys for leisure, over 30 years. There has been some academic debate about this method

Therefore, some elements of the estimated cost to the economy may be more uncertain.

Research undertaken by public health practitioners and Edinburgh Napier University suggests that the estimated reduction in casualties each year from the introduction of the 20mph default speed limit in Wales, could provide around £92m in prevention savings.

We trialled the introduction of a default 20mph speed limit in 8 areas. These were: 

• Abergavenny and Severnside, Monmouthshire
• North Cardiff
• Buckley, Flintshire
• Cilfrew Village, Neath and Port Talbot
• St Dogmaels, Pembrokeshire
• St Brides Major, Vale of Glamorgan
• Llanelli North, Carmarthenshire

You can visit the Transport for Wales (TfW) website to read the final monitoring report and first monitoring report, detailing some of the impacts the introduction of 20mph has had in these communities. Overall speed has reduced in these areas.

In May 2024, Transport for Wales published the 20mph phase 1 air quality monitoring report. The data shows no material effect on local air quality to date.

The World Health Organisation states that the most effective way to improve pedestrian safety is to reduce the speed of vehicles.

Transport for Wales’ 20mph monitoring framework includes the number of casualties on roads in Wales. Multiple years of collision data would be needed from the start of the default speed limit for comparisons to be meaningful.

Data published in June 2024 shows reduced casualties on 20/30mph roads since the introduction of 20mph in September 2023. 

We’ll need to look at the data across several years before we can draw firm conclusions, but it’s encouraging to see things moving in the right direction. 

In 2022, police force figures indicate that 51% of collisions happened on 30mph roads.

A Transport for London report  shows considerable improvements in road safety since the introduction of 20mph speed limits. Collisions resulting in death or serious injury within the central London Congestion Charging Zone showed a decrease of 25%, compared with a decrease of 10% across London as a whole.

By reducing the default speed, it will make it easier for drivers to stop in time to prevent collisions.

According to the Highway Code, in the distance a 20mph car can stop, a 30mph car will still be doing 24mph.

Edinburg Napier University Transport Research Institute points to evidence shows a person is around five times more likely to be killed when hit by a vehicle travelling at around 30mph than they are from a vehicle travelling around 20mph.

Journey times on roads in urban areas tend to be determined by junctions and signals, rather than the speed limit.

In many cases lowering the speed limit to 20mph will have little or no impact on journey times. Where there is an impact, our analysis showed us that the average journey would only be around 1 minute longer but this would make the roads safer for pedestrians and cyclists.

The subsequent final monitoring report from first trial areas for 20mph has found in main through routes, average journey time changes are generally not more than one minute, with some exceptions of up to 2 minutes.

Introducing a 20mph default speed limit should make children safer from the moment they leave home, regardless of where they are going, and keeps them safe inside and outside of school hours.

A 20mph speed limit outside the school won’t protect children for the whole journey as they walk or cycle from home, it would only protect them near the school.

And it won’t just protect children. This change is designed to make streets safer for all of us.

20mph speed limits and zones are common in other parts of the UK and in Europe.

There are 20mph speed limits in many cities in England. Scotland and Ireland are set to extend the use of 20mph and 30kmph speed limits, respectively.

30kmph and 20mph limits are being introduced across the world including in:

• Spain
• France
• Italy
• Finland
• Germany
• Ecuador
• England
• Scotland