Police, fire and ambulance services are allowed by law to exceed speed limits to respond to emergency calls, with many people being fearful that emergency services may be held up by the law changes.
Paul Barker, managing editor at carwow, warned: “Drivers will have to do some serious mental adjustment to account for the arrival of widespread 20mph zones in Wales, and we'd urge authorities to ensure there's equally widespread signage and information to avoid drivers being caught out by a poorly advertised new limit.
“The 30mph urban limit has been in place for getting on for a century, and speed awareness courses even teach that roads with streetlights and no signage can be assumed to be 30mph limit, so large areas of 20mph zones require a complete reset of driving instinct.
“These zones have proven unpopular with motorists when introduced on a big scale in places including London and Brighton, so despite the claimed safety and pollution benefits there is going to be a difficult transition period if 20mph is going to become the new 30mph in urban areas.”
Spain reported much safer roads after implementing similar speed limit changes
Spain was one of the first countries to introduce a 30km/h (18mph) speed limit in 2019, with the nation reporting 20 per cent fewer urban road deaths, and a 34 per cent drop in cyclist fatalities.
Álvaro Gómez, head of the National Road Safety Observatory in Spain, wrote to the Welsh Government reassuring them of the plans, adding that everything had gone well in Spain.
He added: “The main message to the people of Wales is that you can do it. There will be some fears beforehand but our experience and the experience of other cities across the world is that once it is done things become normal quickly.
“There are no big delays, there is no congestion there is no increase of pollution. Everything becomes normal, and everything gets better.”