Edinburgh 20mph speed limits: Deaths, crashes, and casualties reduced by 20mph limit, researchers say

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And it says support for the speed cap has increased since it was introduced, as has motorists’ willingness to obey the limit.

The research was carried out by a team from the universities of Edinburgh, Cambridge, East Anglia, St Andrews and Bristol and Queen’s University Belfast in collaboration with walking and cycling charity Sustrans.

They said accident rates across Edinburgh fell, even without extra traffic-calming measures or police patrols, making the £2.76 million scheme cost-effective.

Although average speeds had only fallen by 1.3mph after a year, the researchers found prior to the new limit, 45 out of 100 cars in Edinburgh travelled above 25 mph. But one year later, the figure had dropped to 31 out of 100.

The study, the UK’s most extensive evaluation of 20mph speed limits so far, said the number of collisions in one year fell by 40 per cent to 367, and there were 409 fewer casualties – a drop of 39 per cent.

A breakdown of the casualty figures showed fatalities dropped by 11 – or 23 per cent – and serious injuries fell by 33 per cent.

The 20mph scheme – which even had its own super-hero mascot The Reducer – was rolled out in residential streets across the city between 2016 and 2018.

And amid concerns about the lack of resources for police enforcement of the new limit, communities were offered a cardboard cut-out traffic cop, Pop-Up Bob, for a two- or three-week deployment to help deter speeding motorists.

Researchers worked with local and national traffic authorities to gauge the effectiveness of 20mph restrictions, They interviewed residents to assess the overall impact and also examined official records and data, and studied how decisions were reached and regulations enforced.

The study also assessed a smaller 20mph scheme in Belfast and concluded that reducing traffic speed also helped to create better quality environments.

Researchers measured liveability – safety, health, sustainability, education, transport, amenities and living standards – and found it improved in both cities after the introduction of the 20mph limit.

But they said they were not able to measure the effect of the lower speed limit on walking and cycling.

Project leader Professor Ruth Jepson, of Edinburgh University, said: “The study shows that city-wide speed reductions can reduce collisions and casualties and that they were increasingly accepted by the local community.”

The city council’s former transport and environment convener Lesley Hinds, who proposed the scheme, said: “It is encouraging to see the reduction in deaths, accidents and speeds. It is also good there is an increase in support from the public in residential streets as well as in the city centre.”

The Belfast scheme, which was restricted to city centre streets, led to a two per cent drop in casualties and collisions. The researchers said the results reflected the scheme’s narrower reach and its implementation in an area where traffic speeds were already low.

The study was funded by the National Institute for Health Research.