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Large reduction in road casualties in Welsh built-up areas after 20mph limit

Rhodri Clark
19 June 2024
Casualties in collisions on roads with 20mph and 30mph speed limits, 2010 to 2023
Casualties in collisions on roads with 20mph and 30mph speed limits, 2010 to 2023


Data for the first full quarter following introduction of the 20mph default speed limit in Wales have revealed a 32% reduction in casualties on restricted roads. This is the lowest figure on record for Welsh roads with 20mph and 30mph limits, excepting the Covid-19 period when traffic volumes were low.

Separate evidence from insurer esure paints a similar picture, showing a 20% fall in claims from Welsh drivers in the last quarter of 2023 – a period of the year when esure would expect claims to increase.

The emerging evidence of health benefits from the change in the default limit has not deflected the Conservatives from their sustained attacks on the policy. Their general election manifesto includes a pledge that a Conservative UK Government would take the extraordinary step of over-riding the Welsh devolution settlement. It says: “We will expand our Backing Drivers’ Bill to cover Wales, reversing Labour’s blanket 20mph speed limit by requiring local consent for 20mph zones and giving local communities the legal right to challenge existing zones.”

Welsh roads are devolved, including the setting of speed limits. The Conservatives do not propose in their manifesto to extend that Bill to Scotland, where the government remains committed to rolling out 20mph limits across Scotland by the end of next year.

In the last quarter of 2022, there were 681 casualties on 20mph and 30mph roads in Wales, mostly on 30mph roads. The default speed limit changed to 20mph on 17 September 2023. In the last quarter of 2023, there were 463 casualties on 20mph and 30mph roads.

Most of those casualties in Q4 2023 were on 20mph roads, reflecting the large increase in roads where 20mph had become the speed limit.

Vehicle mileage statistics for that quarter are not yet available. If the traffic growth known to have occurred in the rest of 2023 continued in the final quarter, the reduction in the casualty rate per vehicle mile would be even larger than the 32% reduction recorded in the above data.

One statistical consequence of the safety improvement in Q4 2023 is a 6.8% decrease in total casualties on restricted roads in Wales in 2023 as a whole. Without the large fall in the last quarter, the total for 2023 would have been higher than the 2022 total.

The data is from STATS19, relating to collisions reported to police. The data excludes collisions not reported to police, ones which occurred on private land or where no personal injury was recorded, and collisions later confirmed to result from suicide or medical episodes.

Officials stressed that one quarter’s data can be influenced by factors such as changes in weather, and it is too early to draw conclusions on the 20mph default limit.

However, there are reasons to believe that the reduction in collisions in the last three months of 2023 will be sustained, if not bettered during 2024. In Q4 2023, drivers were still getting used to 20mph as the norm in built-up areas. It was also well known to the public that none of the new 20mph limits would be enforced during that quarter.

There is also evidence that compliance with the Welsh 20mph limit is continuing to improve.

Claims to esure from car drivers in Wales have continued to decline this year, following the 20% drop in Q4 2023. Rob Clark, esure’s head of motor underwriting, said: “We can see a clear drop in claims for car accidents in Wales since the 20mph speed restriction was introduced in September 2023. During a time when we usually see these claims rise, they dropped and have continued to do so in Q1 2024. PANEL

Drop in road casualties may have saved NHS millions

The reduction in road casualties in Q4 2023, compared with Q4 2022, may have saved the NHS approximately £3.7m, according to a rough and ready calculation by LTT.

The DfT ascribed a value of £2.329bn to the response by medical and ambulance services to road casualties in Great Britain in 2022. There were 135,480 road casualties in 2022, giving an average value of £17,191 per casualty for medical and ambulance response.

Using this average, the 218 fewer casualties on Welsh 20mph and 30mph roads in Q4 2023 than in Q4 2022 represent a saving of £3.748m to the medical and ambulance services.

The DfT ascribed in 2022 an average value of £92,168 per road casualty prevented. This includes “human costs” – the largest component – as well as police costs, insurance, damage to property, lost output and medical and ambulance costs. Human costs are calculated using people’s “willingness to pay” for reductions in risk exposure and relate to non-resource costs, such as pain and distress for victims or relatives and, for fatalities, loss of enjoyment of life.

Using this average value, the Welsh reduction in casualties on restricted roads in Q4 2023 would equate to an overall saving of approximately £20m. If the casualty figures in Q1 2024 prove to be similar, the savings associated with the 20mph default limit will have exceeded the £34m implementation cost within the first six months.

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