Wales’s 20mph speed limit saves lives and money. So why has it become a culture-war battlefield? | Will Hayward

Imagine you're a politician running a country. In front of you there is a proposal that in just nine months would save your society more than £45m, prevent almost 500 people being killed or injured, make your residential areas more appealing places to live in and reduce car insurance premiums by an average of £50. Tempting, right?

Still not convinced? It is also backed by multiple scientific studies and examples of where it has been enacted in other parts of the world. Better yet, it was in your manifesto at the last election, when you became easily the largest party in your parliament. It also has the universal support of all emergency services in your nation. This is the dream.

Yet this is exactly what happened in Wales and it became the single most unpopular and controversial piece of lawmaking in the (admittedly short) history of our Senedd (parliament). I still can't quite get over the fact that a scheme designed to save the lives of children became the latest culture war battlefield.

In September 2023 the Welsh government introduced the default 20mph speed limit , changing every road in Cymru that had a 30mph limit to 20mph unless it was given an exemption by the local authority. Essentially, almost everywhere people lived in Wales now had slower speed limits. The evidence that this would save lives was unequivocal and overwhelming.

The response from some to the policy was unrestrained fury. A petition on the Senedd website opposing the new measures has reached nearly 470,000 signatures (in a nation of just over 3 million people).

Protests sprang up citing the cost of the policy ( £32m , mostly on changing the road signs and markings). Some of them were somewhat counterintuitive – many of the 20mph signs were vandalised, meaning they had to be replaced at additional cost. And to show their displeasure at having to drive slower through communities, protesters also held a go-slow drive on the M4 and several other major Welsh roads.

A far from exhaustive list of other gripes included that it would apparently result in more emissions ( it probably won't ), it would "destroy" car engines, it would increase congestion, and road rage incidents would spike. As I reported on the policy, I couldn't believe my inbox. One taxi driver sent me furious messages claiming that accidents would "skyrocket" because people like him would be constantly "staring at the speedometer" rather than looking at the road. This seemed an odd admission for a professional driver to make.

However, a year on from the scheme's introduction we can see pretty strong evidence that the 20mph limit is very effective in saving lives and preventing injuries. We now have the road collision data for the first three quarters since the policy was introduced and the figures are pretty clear. Compared with the same period the year before, the number of people killed on the affected roads is down 35%, serious injuries are down 14.2% and slight injuries 31%.

Leaving aside all the children who won't be killed, the lives not ruined, there is also a massive financial benefit. The Department for Transport estimates that the total societal cost of someone being killed on the road is just over £2.4m. A serious injury is £271,000. Even a "slight" injury is nearly £21,000. If we apply these estimates to the first nine months in Wales we can see the savings that the 20mph change has made . On roads affected by the change there were 10 fewer deaths compared with the previous period, saving £24m. In just nine months there has been a total saving of £45.5m – not even counting the long-term savings to the NHS from people taking up cycling or walking instead of driving, or the savings for many Welsh drivers caused by the reduction in their insurance premiums . Makes that £32m on new road signs and markings look like a pretty smart investment, right?

So why all the outrage? Well, it turns out that much of it was manufactured. In January of this year I did a little digging through four of the main Facebook groups opposing the change to 20mph in Wales. I found that in each case one of the admins was a Tory councillor from Sunderland who has, and this is hilarious, campaigned to have 20mph limits in parts of his home town.

One of the other admins shares a name with a man who was a Tory candidate in Burnley in 2021, another had the same name as the election agent for Vale of Glamorgan Conservatives, while one was seemingly a partner of a Tory Senedd member. Since the policy came in, the Welsh Tory leader, Andrew RT Davies, has been very critical of it , calling it a "blanket" speed limit (which is odd as it isn't a blanket policy ).

The most shameless part is that the Tories know the policy works. Back in 2018, Davies himself proudly posed with a poster saying "20's plenty where people live". In a debate in the Senedd in 2020 the party overwhelmingly supported the policy, with the then leader Paul Davies voting in favour (though Davies did not attend).

The Welsh government itself has been far from flawless in its implementation. It spent only £1.6m of the £32m total cost on explaining the policy, focusing on telling the public that it was coming in, but not why. And the government has since tried to distance itself from the policy, even as evidence of its effectiveness grows. Recent public pronouncements have emphasised that the government has "listened" and decided that some roads will revert to 30mph.

Ultimately, the 20mph change was an attempt to rebalance the communities in which we live, so they are no longer dominated by cars. The policy aims to make our neighbourhoods more livable (20mph is three decibels lower than 30mph). It has a positive impact on particulate pollution because cars have to brake less. And it clearly saves lives.

The experience in Wales is a lesson for the wider UK and beyond. Evidence-based policy does work, but you have to own it, explain it and stay the course. It costs political capital, and politicians need to be brave. In a world where facts and evidence matter less and less, it is all the more vital that we stand by that evidence to take our nation forward (at an appropriate speed).