The surprising results of Wales’ new 20mph speed limit

In mid-September 2023, the Welsh government implemented a then-deeply-unpopular policy: A default 20 miles an hour (32km/h) speed limit on roads where cars mix with pedestrians and cyclists. With some exceptions, it applies to all residential areas and cities.

The aim, according to policymakers, is to reduce the number of collisions and severe injuries — in part to take strain off the healthcare system — to encourage more people to walk and cycle for short, every-day journeys, to promote social cohesion, and to improve air quality.

During initial trials of the policy in certain areas — before the national roll-out — the transport department found that:

• Even though compliance with the 20mph limit was high, mean journey time increases during the morning and afternoon peak periods were “minimal and generally not more than one minute”. This is partly because traffic simply flowed better.
• Many bus routes became more punctual (although some became less so).

Similar findings were made by consulting firm Agilysis, which monitored changes in commuter behaviour in the week after the rules went national. It found that:

• Average traffic speeds declined by 2.9mph, to slightly below the new limit.
• Despite this, average journey times increased by only 45-63 seconds.

“The immediate impact on traffic speeds in Wales has been astonishing, and far greater than many would have predicted,” Richard Owen, Agilysis CEO, said in a statement. “Welsh drivers are, on the whole, accepting lower speed limits and have changed their behaviour accordingly.”

It is too early to tell whether the reduced limit will have a significant impact on road deaths and injuries, and if it will substantially improve air quality.

But although compliance rates have been high, not everyone’s on board with the new policy.

Conservative party members and supporters have been driving vans around the country with the message: ’20mph isn’t working’, according to a post on X by Andrew RT Davies, a member of parliament. And ITV reported that some fire and rescue service officers are concerned that response times could be impacted, even though fire engines can exceed the speed limit.

Meanwhile, Amsterdam is preparing to lower its default speed limit to 30km/hr (18mph), with the aim of creating safer and quieter roads.

According to a report by NL Times, it is estimated that this will result in 20-30% fewer serious accidents.