From 83 percent in 2020 to 78 percent in 2023, fewer major roads have a 70-mph speed restriction.
In order to meet net-zero air pollution targets for 2050, many local authorities are cutting speed limits.
The research revealed that 15 percent of roads managed by National Highways now have a 60 percent speed limit, an increase of nine percent in 2020.
Across the UK, there are now 1,694 miles of major roads with a 60mph speed limit due to the reduced speed limits.
There is a 905-mile increase from 2020, when there were only 925 miles of major roads with lower speed limits.
The A1, M11, A52, and M20 all have 60-mph speed limits for their entire lengths.
Head of Churchill motor insurance, Nicholas Mantel, commented on the speed limit changes and how they will affect motorists on the road.
He said: “Our research shows 60mph speed limits are becoming more common on motorways, so it is important drivers check the signage on each stretch of road or they could risk unexpected fines.
“Many drivers will be surprised to learn that major A-roads across the UK have speed limits as low as 30mph, with controls in place for local safety reasons such as near schools.
“With variable speed limits, changes in permanent limits and temporary road control drivers can’t always rely on phone apps and in-car navigation to identify the speed for the road.”
Growing from nine percent in 2020 to 15 percent in 2023, this was the biggest change in speed limits on roads which are now 60mph.
To cut pollutants and enhance air quality, National Highways has increased the number of 60-mph speed limits along some stretches of motorways.
Because of the reduced traffic, there is an expectation that nitrogen oxide levels will drop, with provisional data suggesting a 17 percent cut.
To make roads safer in non-urban areas and to slash the rate of pollution, more rural areas are introducing slower 20-mph speed limits.
Last year, the Welsh Government announced that it would be introducing a default 20mph speed limit on restricted roads across the country, from September 17.
Restricted roads are typically found in densely populated residential and built-up areas, frequently with street lights 200 yards or less apart.
This is being done to increase the number of people who walk and cycle in our communities and decrease the frequency of collisions and serious injuries.
The changes were discussed and disputed by Lee Walters, Deputy Minister for Climate Change and Member of Parliament for Llanelli.
He said: “The idea that being a minute later to get to school harms the economy, I just don’t believe it.
“So I think the figures are discredited, in my view, and there’s a movement to change that. Also, it’s going to save lives – we know it’s going to save lives,” the BBC reported.
To keep roads safe and educate motorists on the new rules, the police will continue to enforce 20mph.
These new regulations are intended to alter driving behaviour and increase road safety for motorists. Additionally, there is a chance that traffic will move more easily.