Introducing 20mph speed limits: frequently asked questions

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.

Research undertaken by public health practitioners and Edinburgh Napier University suggests that the 20mph default speed limit in Wales could result – every year – in around:

• 40% fewer collisions
• 6 to 10 lives saved
• 1,200 to 2,000 people avoiding injury

The change is also intended to:

• make streets safer for playing, walking and cycling
• encourage more people to walk, wheel or cycle
• makes our communities safer
• improve health and wellbeing
• reduce noise pollution

The legislation was approved by the Senedd in July 2022.

These changes affect most roads that were 30mph before 17 September 2023, but not all.

The law changed the default speed limited on restricted roads. These are usually residential or busy pedestrian streets with streetlights. 

We provided local authorities with guidance to help them to choose which of their roads should remain at 30mph.

We have published a map on DataMapWales that shows which roads have stayed at 30mph.

The introduction 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. Our Welsh transport appraisal guidance (WelTAG) specifically excludes consideration of journey time savings for private car users as a benefit (and by implication, journey time delays as a detriment) as this does not support the priorities and ambitions of the Wales Transport Strategy.

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

We used the experiences in the trial areas to help us understand how to best to introduce the 20mph ​default across Wales.

The feedback also allowed us to improve the guidance to local authorities on how to identify which roads should be excepted from the new default speed limit. 

Early 20mph data published by Transport for Wales in February 2024, shows that speeds have reduced by an average of 4mph on main roads since the national rollout of the default 20mph speed limit. Further monitoring continues and will be published.

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.

As the Fire and Rescue Service attend more calls to road traffic collisions than house fires, they have a dedicated road safety team. These teams are not involved in callouts to emergencies and aim to inform drivers about the consequences of collisions caused by speeding.

Having seen the results of many collisions, they are well placed to engage drivers and are involved in this aspect of the 20mph roll-out.

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.

There is a review, by an independent panel, looking at how exceptions criteria was used by highway authorities when deciding whether or not the speed limit on a road should be 20mph.

The initial report by the independent Review Team, was published in February 2024. It sets out a series of early findings and initial recommendations. 

The Highway Code was updated online on 17 September 2023 to reflect the 20mph speed limit in Wales.

The driving theory and practical tests have also been amended by the DVSA.
 

Lower speeds mean that people feel more comfortable to walk and cycle and it is safer for children to walk to school. Older people, disabled people or people with additional needs will feel more able to travel independently.

Vehicle speeds are one of the key reasons why people do not walk or cycle or do not allow their children to walk or cycle to school.

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

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.

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

Gateway speed limit signs, the larger signs shown as you enter a different speed limit area, are in place to clearly indicate the correct speed limit in built up areas (30mph or 20mph).

20mph repeater signs, the small circle signs often seen on streetlights, are no longer allowed on roads where the default speed limit is now 20mph. However, since they display the correct speed, highway authorities will have 12 months from the coming into force date to remove these signs. This is also the case for 20mph zone signs outside schools and highway authorities have up to five years to remove 20mph signs painted onto road surfaces.

In any 20mph areas where there aren't streetlights present, additional signage is in place to clearly indicate the speed limit.

Remember, in built up areas if you see streetlights think 20mph, unless signed otherwise.

There is no plan to include traffic calming (including speed bumps) as part of the change to speed limits. There are other ‘softer’ measures that might be introduced, such as using buffer speed limits, removing the centre line, narrowing the carriageway visually, using planting etc.

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.

Speed limits in the Road Traffic Regulations and the Highway Code apply to motor vehicles only and not to bicycles.

The Highway Code has been updated to include 3 new rules about the new ‘hierarchy of road users’.

The hierarchy places those road users most at risk in the event of a collision at the top of the hierarchy. It does not remove the need for everyone to behave responsibly.

It’s important that all road users:

• are aware of The Highway Code
• are considerate to other road users
• understand their responsibility for the safety of others

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