Accidents in 20mph zones rise nearly 150% in three years

The number of accidents that happen in 20pmh zones increased by 148% in three years as drivers continue to ignore the slowest speed-restrictions across the UK, according to new research by Britain’s leading garage comparison site,

20mph zonesJust 13% of drivers in the UK adhere to 20mph limits on the road, despite the slow zones accounting for more than 10,000 accidents a year.

The research comes while a growing number of councils introduce 20mph limits to improve road safety and reduce accidents.

Analysis of Department for Transport (DfT) figures on speeding found 86.88% of drivers in the UK exceed the speed limit on 20mph roads, with the average speed measured at 26mph*.

The analysis suggests that, as the number of 20mph zones rises, so do the average speeds of motorists using them. Since 2017, the average speed of motorcyclists in 20mph zones has increased from 27mph to 30mph, while van drivers’ average speed has also gone up from 25mph to 26mph during the same period.

The latest DfT Road Casualty Report shows that there were 10,661 accidents in 20mph roads in the UK in 2018**, accounting for nearly one in 10 of all road accidents for the year. Head of Marketing, Jessica Potts, said: “It’s been proven that 20mph zones help improve traffic flow and cut down on accidents, with the DfT’s own research suggesting 20mph zones work best when the average speed is below 24mph***.

“But the zones have been largely despised by motorists, who find it painfully slow going to drive through them, which is probably why the limits are being roundly ignored.”

To see a heatmap showing where the most accidents happen in 20mph zones across the UK, visit

*Source: DfT



  1. In my opinion, the number of accidents has increased in these particular zones because the number of the zones has increased significantly. As a driver I did used to take note of the few 20mph zones and drove at the speed limit as they were rare and only on busy high streets and streets with a high number of pedestrians (train stations and bus stations), so in my opinion they were justified reasons to implement this change.
    London now has plenty of these roads with no difference between the quiet residential side streets, busy high streets and main roads. Just blanket changes to tick boxes.
    As the number of 20mph zones has increased I find that I no longer take note and default to the previous speed limit. I do drive through the areas which are busier with a high number of pedestrians at a lower speed as this is common sense, but a lot of the changes didn’t and don’t have much traffic and therefore driving at 20mph is painful and unnecessary.
    For the roads which have been changed for the sake of implementing this change London-wide I cannot say I will stick to this speed limit, its unjustified.

  2. There has been a large increase in crashes on 20mph roads because there has been a large increase in the number of 20mph roads. It is patently obvious that if you convert 30mph roads to 20mph you will increase the total casualties on 20mph roads and decrease total casualties on 30mph roads.

    The DfT report on compliance was only on 9 “free-flowing” roads where there were no houses or hazards. In fact the report said that these roads were “atypical” of most 20mph schemes. Even considering this, speeds on the “free-flowing” 20mph roads were 6mph less than on “free-flowing” 30mph roads.

    Converting 30mph roads to 20mph has resulted in reductions of the order of 20% on those roads in Bristol, Calderdale, Edinburgh and many other places. Recently 130 road safety ministers from around the world called for the default speed limit in urban/village streets to be 30km/h or 20mph. Intelligent Speed Assistance speed limiters will be mandatory on all new car models from 2022 and will further increase the success of 20mph limited streets.

Advertise here