20mph speed limits

As Welsh Government has begun its review of the 20mph speed restrictions, Denbighshire County Council is inviting residents to get in touch to propose additional exceptions to the 20mph speed limit. All suggestions should be sent to traffic@denbighshire.gov.uk by 30 June 2024. After the closing date, we will assess all proposals against the new Welsh Government criteria.

You can find further information about the review on Welsh Government's website:

20mph speed limits

About 20mph in Wales

Since 17 September 2023, a new default 20mph speed limit applies to roads in Welsh cities, towns and villages that have street lights.

The Welsh Government (external website) made this change for a number of reasons, including:

  • reducing the number of collisions and severe injuries from them (also reducing the impact on the NHS from treating the people who are injured)
  • encouraging more people to walk and cycle in our communities
  • helping to improve our health and wellbeing
  • making our streets safer; and
  • safeguarding the environment for future generations

According to the World Health Organisation, the most effective way to improve pedestrian safety is to reduce the speed of vehicles. The evidence from around the world is very clear - reducing speed limits reduces collisions and saves lives. In the distance it takes for a car travelling 20mph to stop, a 30mph car is still moving at 24mph. This makes a substantial difference to the ability to avoid collisions. When a pedestrian is hit by a vehicle travelling at around 30mph they are around five times more likely to be killed than when hit by a vehicle travelling around 20mph (external website).1

Public information and Frequently Asked Questions


Public Health Wales believe that lowering the default speed limit to 20mph could have substantial health benefits. 20mph will reduce the risk of collisions, help people feel safer and benefit people’s physical and mental well-being. A recent public health study2 estimated that the 20mph default speed limit could result in:

  • 40% fewer collisions
  • saving 6 to 10 lives every year; and
  • avoiding 1,200 to 2,000 people being injured every year.

This would save around £92 million in prevention during the first year alone.


There is also evidence from across the world that vehicle speeds are one of the main reasons why people do not walk or cycle or do not allow their children to walk or cycle to school. Lower traffic speeds will create more liveable communities and encourage walking and cycling. People will feel more comfortable when walking and cycling. It will be safer for children from the moment they are outside their homes, playing or walking to school, while older people will also feel more able to travel independently and safely.

Driving slower produces less noise, reduces fuel consumption, and exhaust and non-exhaust emissions are also likely to be reduced. Accelerating up to a reduced speed of 20mph, and driving at a more consistent speed, should result in lower tyre, and brake abrasion3 and this can also save on your fuel costs (external website)4.


The speed limit on restricted roads will usually be changed to 20mph.

However, it is recognised that not all roads with a currently at 30mph limit will be suitable to change to 20mph. These roads will be known as exceptions.

Based upon Welsh Government criteria (external website) and subsequently, the views of our County Councillors, we have identified some roads that will potentially remain at 30mph. We will be consulting with local communities on those roads that are proposed to remain at 30mph.

Welsh Government have published a map on DataMapWales (external website) that will show which roads will remain at 30mph, including a DataMapWales user guide (external website).

We are currently finalising this information which will be available soon to view on the DataMap Wales website.

Latest news and updates

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20mph speed limits

Related websites


  1. Davis, A. 2023 Essential Evidence 4 Scotland No.63 Impact speed and pedestrian fatality risk, Transport Research Institute (external website)
  2. Jones, S., Brunt, H. 2017 Twenty miles per hour speed limits: a sustainable solution for public health problems in Wales, Journal of Epidemiology and Community Health, doi:10.1136/jech-2016-208859
  3. Williams, D., North, R. 2013. An evaluation of the estimated impacts on vehicle emissions of a 20mph speed restriction in central London
  4. NICE, 2017 Air pollution: Outdoor air quality and health, NICE Guideline (external website). London: NICE