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Seven questions about Wales’s new 20mph default speed limits

We recently became the first UK nation to pass legislation to lower the default national speed limit on residential roads and busy pedestrian streets from 30mph to 20mph when the Senedd voted in favour in July this year. Work is now underway to get Wales ready for that change, as limits will begin to change from September next year.

Here are seven things you may not know about the new 20mph default speed limit:

  1. Will it improve safety?

Yes, and the evidence is clear. Decreasing speed limits reduces collisions and saves lives. Previous research has shown that there are 40% fewer collisions in areas with 20mph compared with 30mph. In Wales, it has been estimated that with widespread introduction of 20mph, somewhere between 6 to 10 lives would be saved and between 1200 and 2000 casualties avoided each year. The value of preventing these casualties is between £58m and £94m each year.

As well as making collisions less severe when they do happen, the slower speed also increases the chances of avoiding a collision in the first place and reducing the burden on the NHS. Prevention is better than cure!

2. Will it improve the environment and help create safer communities?

Whatever car you have, getting to 30mph requires more than twice as much energy as getting to 20mph. In fact, evidence suggests that as a result of smoother driving styles, reducing braking and acceleration, improved traffic flow, and possible reductions in fuel consumption, 20mph produces less air pollution than 30mph.

People surveyed say that traffic speed is a barrier to walking and cycling for short journeys, so by lowering the speed limit, we’re helping to create safer, quieter, and more pleasant environments where people feel safer to walk and cycle, further reducing air pollution and benefiting people’s health and the local economy. Welsh communities will become better places to live.

3. Do people support it?

People living in communities where 20mph is already the default speed limit are positive about the change. Evidence from a survey conducted on behalf of the Welsh Government showed that the majority of people were in support of the new lower speed limit – almost two thirds of people surveyed said they would support a speed limit of 20mph in the area they live and 55% saying that ‘streets would be a lot nicer for pedestrians with a 20mph speed limit’. 62% of people also said they wanted ‘drivers to slow down a bit on our roads’.

4. Will people observe the limit?

The 30mph speed limit for residential areas was set before World War II, when there were far fewer cars on the roads and speed limits were set without the wealth of research and data that we have now. Research indicates that the vast majority of drivers observe speed limits on residential streets.

5. Is it a blanket approach?

No. Currently 30mph is the default speed limit for streets with street lighting, but there are variations to that limit marked by signs on the road. In the same way, under the new 20mph legislation, local councils can use their local knowledge to retain a 30mph limit where there is a case for doing so. These 30mph roads will be marked by signs in the same way that variations from the current default speed limit are used.

6. Who else is doing this?

The benefits of reducing speeds are becoming recognised all over the world. 120 countries recently signed the Stockholm Declaration on Road Safety, agreeing that reducing the speed limit to  20mph will improve road safety. In 2021 Spain set speed limits in urban streets to 30km/h (equivalent to 20mph) and now other European countries have 30km/h limits for most of their local roads. Closer to home, areas like central London, the Scottish Borders, Lancashire and Cheshire and Chester have made 20mph the default speed limit for residential streets.

7. When will it come into force?

The new 20mph default speed limit will come into force in September 2023. This will arguably be the biggest change to Welsh roads since the wearing of seatbelts was made compulsory in 1983. It is a big change, but like wearing a seat belt, adapting your driving to the new speed limit will become as natural as driving at 30mph is now!

Lee Waters, Deputy Minister for Climate Change

Have more questions on this? Read our FAQs here.

Darllenwch y dudalen hon yn y Gymraeg.


  1. Robert on

    A waste of money and time. Just because you put a sign up saying 20 do you really think that people will do 20 total waste of money. Spend the money where it’s needed more not waste it on road signs.

  2. Abbas on

    Study in Bristol shows it has not improved safety and there is no significant difference between 20, 30 and 40 so stop telling lies

  3. Ian James on

    What a load of rubbish. I live in a pilot scheme area and the locals hate it and only 10% comply. It was not in the labour government’s manifesto and disgusting to implement.

  4. Big Axe on

    Didn’t realise Wales is working with London, thank one of your vans came to help Reg: CV20ECE working. London’s gone downhill

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