Last month a review of Bristol’s 20mph areas was published by UWE with coverage in local media (here, here and here). This adds to the growing weight of evidence backing city-wide lower speed limits (unlike a widely ridiculed ‘report’ from Bath and North East Somerset Council (BANES).

UWE’s Bristol Twenty Miles Per Hour Limit Evaluation (BRITE) study found that, on average, speeds on more than 100 surveyed roads have reduced since the 20mph speed limits were implemented, with average speeds of between 19mph and 26mph on 20mph roads shown in the report.

On 30mph streets, average speeds on the roads surveyed were below 30mph in every area.

The lower speeds were also found during night and summer times, when there is typically less traffic to slow motorists.

Other key findings were:

  • Statistically significant reductions in average traffic speeds of 2.7mph across the city of Bristol, following the introduction of 20mph speed limits. This is a larger reduction than seen in previous evaluations in other cities.
  • The study employed a more sophisticated analysis than previous studies of 20mph limits, including using individual speed data from over 36 million vehicle observations and controlling for other factors that might affect changes in traffic speeds.
  • There has been a reduction in the number of fatal, serious and slight injuries from road traffic collisions. Casualties avoided per year are 4.53 fatalities, 11.3 serious injuries and 159.3 slight injuries.
  • These equate to an estimated cost savings of over £15 million per year. This is an annual savings over 5 times greater than the one-off implementation cost of £2.77m.
  • Although there is still majority support for 20mph speed limits in Bristol, there remains concern about compliance and behaviour of other drivers.
  • Walking and cycling across Bristol has increased, both among children travelling to school and adults travelling to work.
  • The introduction of 20mph speed limits in Bristol offers a model for other towns and cities across the UK, who are seeking to reduce traffic speeds, cut road traffic casualties, and promote community health and well-being through road danger reduction.
  • In order to assess effectiveness of 20mph speed limits, it is vital that other towns and cities follow Bristol’s example, and prioritise the ongoing collection and analysis of appropriate data on vehicle speeds, road traffic casualties and wider public health impacts.

The Bristol Twenty Miles Per Hour Limit Evaluation (BRITE) Study -Pilkington, P., Bornioli, A., Bray, I. and Bird, E. (2018) – http://eprints.uwe.ac.uk/34851

Bristol Health Partners headed their piece on the report 20mph speed limits in Bristol save lives, reduce injuries and save the NHS £15 million a year.

The report will be used in Bristol’s 20mph review to start this Spring. There are hopes that this latest research will act as a brake on any attempt to reverse 20mph or diminish its scope, notably from Cllr Mark Bradshaw in a guest blog on Sustrans website, Making the case for 20mph speed limits in Bristol. He was closely involved in the planning and implementation of this innovative change for Bristol. In the blog, he shares with us why he originally supported the implementation of 20mph limits, and why he still believes in the programme.

I was convinced by two factors in particular during my time in Cabinet:

  1. Evidence that people, especially children, in disadvantaged communities, were up to six times more likely to suffer injury (or worse) by being hit by a speeding vehicle than those from more affluent areas.
  2. Also, that people involved in a collision at 20mph are more likely to survive without serious injury or death, despite the trauma and potential for some injury compared with 30mph and above.

So, it was both an issue of equality and survivability. There is a similarity here with air pollution and the greater exposure to toxic air experienced by populations in poorer areas.