Welsh drivers who break the new 20mph speed limit will be slapped with fines from today, officials have warned.

A three-month “grace period” has been in place to allow people to adjust to the change and to allow Highways authorities to adjust road signage and Traffic Regulation Orders. However, this period ends today, even as there remains some confusion over where the 20mph areas are.

Many of the roads effected by the change used to be labelled 30mph. A petition earned hundreds of thousands of signatures speaking out against the new speed limit, describing it as a “foolish idea”.

The Welsh Government said the measures were made to “save lives” and make streets safer, as well as improve pollution. The Labour-led authority also hopes the scheme will encourage residents to walk or cycle more.

But a petition calling for a u-turn on the scheme has amassed more than 460,000 signatures. The petition’s creator, Welshman Mark Baker, claims the government has failed to prove the speed limit reduction will save lives.

“The Welsh government has failed to produce any convincing evidence to support these claims of safety,” Mr Baker wrote. 

“This law is being spearheaded by the WG Climate Change department and not Health & Safety!”

He added: “You have not listened to us. The Welsh government was put there by the people of Wales. We are your boss! We demand that this foolish idea be stopped.”

Enforcement was temporarily halted in September to enable people to get used to the change. Welsh Deputy Climate Change Minister, Lee Waters, confirmed in October that the enforcement would launch on December 17.

GoSafe, the road safety partnership in Wales, has said the change will not impact the level of enforcement but will instead “increase roadside engagement.”

The enforcement thresholds for issuing tickets will reportedly be set following NPCC guidelines of at least 10 percent as well as 2mph, making a limit of 24mph. But to ease the transition, police chiefs have increased the threshold to 10 percent plus 4mph in 20mph zones – meaning drivers will face prosecution from driving at 26mph.

Those caught speeding significantly over 20mph in these zones will face points on their licence, as well as a speeding fine.