Bristol’s 20mph scheme ‘offers a model for other towns and cities’

09.12 | 14 February 2018 | | 13 comments

Image: UWE Bristol, via Twitter

The introduction of 20mph speed limits across Bristol has resulted in a 2.7mph fall in average traffic speeds – a ‘larger reduction than seen in previous evaluations in other cities’.

That is the conclusion of academics from the University of the West of England (UWE Bristol) who have evaluated the impact of the scheme on behalf of Bristol City Council.

The roll-out of 20mph limits across Bristol took part in six phases between January 2014 and September 2015. Along with reducing traffic casualties, the scheme was introduced to improve health and wellbeing across the city.

The researchers used a variety of data sources to examine changes in vehicle speeds, road traffic casualties, levels of walking and cycling, public perceptions and attitudes, and reported levels of health and wellbeing.

The study also employed a ‘more sophisticated analysis than previous studies of 20mph limits’ – including using individual speed data from more than 36 million vehicle observations, and controlling for other factors that might affect changes in traffic speeds.

Alongside the ‘statistically significant’ reduction in average traffic speeds, the study found that the scheme led to a reduction in the number of fatal, serious and slight injuries from road traffic collisions – equating to an estimated financial saving of more than £15m per year.

According to the report, an average of 4.53 fatalities were avoided each year, along with 11.3 serious injuries and 159.3 slight injuries.

Looking at the wider public health effects, the report found that the number of people who walk or cycle to work in Bristol has increased between 2010 and 2015 – with more people walking or cycling for 10 minutes or more in their local area on most days.

The percentage of people who walk to work has increased from 17.5% to 18.9%; while the number commuting by car fell from 53% to 44%. Rates of cycling to work also increased, up from 11% to 15%.

More children also now walk (59%) or cycle (31%) to school following the introduction of the 20mph speed limits.

In terms of public support, the report found that the ‘clear majority’ are in favour of the 20mph limits, with 62% supporting their use on residential roads and 72% on busy streets.

However, the report found scepticism among local residents about the lack of enforcement and a lack of compliance from ‘other drivers’. The researchers also identified an ‘increased readiness to report that it is sometimes okay to drive above the posted speed limit on residential roads’ among local residents who were interviewed for the study.

The academics conclude that 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’.

They also suggest that in order to assess the 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’.

Welcoming the report, Rod King MBE, founder of 20’s Plenty for Us, said: “Default 20mph limits are an important foundation for making our places better places to be. They are affordable, reduce speeds, reduce casualties and make our places more friendly for walking and cycling.

“This study shows that the public health benefits are significant. It is now time to standardise on a 20mph default at national level to increase benefits, reduce implementation costs and maximise the excellent return on public funds.”


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    The ‘model’ headline of the article is a quote from the rather shameless self promotion in the authors report. I give credit for some of the detailed nature of some aspects of the report but the report is far from comprehensive, missing out some keys aspects altogether. Also some of the points are underplayed and need expanding upon to avoid leading people to draw incorrect assumptions.

    I wouldn’t endorse using this model as it is not fit for purpose in its current form.

    Pat, Wales
    Agree (8) | Disagree (1)

    Overall the introduction of the 20 mph speed limit seems to be a huge plus. Less fatalities, casualties and a saving financially; obviously to the Police, ambulance and hospitals apart from the grief of families who lose loved ones in road collisions. I agree however that it needs to be enforced because for some reason a lot of drivers seem to regard speed limits as a personal infringement of their rights rather than a safety issue. When one has seen the result of a death or life changing injury to a person it changes one’s perception completely. Let’s bring it countrywide and save more lives.

    Judi Best, Tunbridge Wells
    Agree (6) | Disagree (7)

    I don’t think the actual speed limit influences whether vulnerable road users use certain roads or not Paul, it is the actual speeds on the roads and obviously the frequency of the vehicles that people are conscious of, as indeed would I be, if I am walking or cycling, but probably more to do with annoyance than personal safety.

    Hugh Jones
    Agree (0) | Disagree (0)

    Bob Craven : “Now perhaps that we have given space to vulnerable pedestrians and cyclists ”

    You are joking ! I use a cycle lane (Feeder Rd, Bristol) which is continually driven in as a large proportion of the road is taken over as a car park.

    Paul Luton, TEDDINGTON
    Agree (2) | Disagree (1)

    “I know of several such places where not even the residents walk their dogs and everyone travels everywhere by car.”

    Don’t you think that this unhealthy behaviour is precisely what a 20mph limit is intended to change?

    Paul Luton, TEDDINGTON
    Agree (2) | Disagree (2)

    Hugh – possibly the best indication of success would be an increase of vulnerable road users willing to use the streets in question.

    Paul Luton, TEDDINGTON
    Agree (2) | Disagree (0)

    If the speed limit of 20 miles/h didn’t work in the 20th Century, why should it work now, I wonder?

    I’m in favour of 20 miles/h limits in appropriate places, but not without mandatory ISA, to help drivers.

    TfL seems to be leading the way … why isn’t central government? More money to be made from prosecutions?

    Andrew Fraser, Stirling
    Agree (2) | Disagree (5)

    I think 20 zones should be taken as a message to drivers that the environment they’re entering requires a different style and attitude of driving, acknowledging and respecting the fact that it is a residential area. Trying to ‘prove’ they’re a success – however that may be defined, using collision numbers for example – is not really the point. If you like, a message to drivers, that they do not come first in such areas.

    Hugh Jones
    Agree (5) | Disagree (1)

    So what happened on Mowcroft Road? The report says that average speeds were 19.47mph when it was a 30 speed limit. Yet after it changed to a 20 speed limit average speeds went up to 30.78mph.

    Guzzi, Newport
    Agree (7) | Disagree (0)

    I agree Pat. According to a police source, I asked the question of ‘Ask the Police’ on their website and they answered that it was initially considered that the implementation of the 20 mph scheme would be found more suitable where the speed of vehicles was assessed and found to be well lower than the 30 mph limit for that street or road anyway. With readings more in line with a 20 mph limit. So the idea was to pick out easy targets to reduce an already slow speed to a slightly slower one. No doubt for justification purposes and propaganda.

    Unfortunately we now have 20 mph limits through villages or hamlets where historically there has been no accident that could justify the implementation of such a scheme and the limit was adopted probably out of the concerns of a few rather than the whole.

    Its easy to look at such a scenario using Crashmaps and determine whether or not there have been incidents that may justify the reduction to 20 mph at some time in the last 15 years. I know of several such places where not even the residents walk their dogs and everyone travels everywhere by car.

    I hope that no one believes that I have just given the 20 is plenty scheme an accolade. That was not my intention. I just merely mentioned that if it saves lives and reduces injuries then that is basically enough to warrant its usefulness within the framework of road safety initiatives. Now perhaps that we have given space to vulnerable pedestrians and cyclists maybe we can concentrate on the giving of space etc. to all other road users.

    Bob Craven
    Agree (4) | Disagree (6)

    No paradox, Pat. Given the choice between someone driving down my street at 24 or 31 mph, I choose the former, whether legal or illegal. It’s safer for me, my elderly mother and my children, as well as being quieter and better for the environment. The evidence is stacking up to confirm the theory that 20’s Plenty in residential streets and in town and village centres.

    Agree (12) | Disagree (9)

    I am continually entertained by the irony in road safety. Just a few days ago we had a message from the National Police Chiefs’ Council lead on roads policing indicating that anything from 31mph onwards in a 30 is over the speed limit and the options for a police response (court, course or fpn) are discretionary based on the circumstances. Yet when 20mph speed limits deliver speeds as low as 24mph it seems as though it is thought to be a success and worthy of an accolade. What a paradox.

    Pat, Wales
    Agree (14) | Disagree (6)

    There was a lot of reading and I got into some trouble deciding what was factually true and part of the report by the University and other passages that might be cosmetic facts initiated and included by interested parties that could possibly flower the report to a more positive conclusion for the scheme, its implementation and costing.

    Some of which I read was assumption and estimation and I never do like those words as they cannot be absolutes.

    What I do feel is that it appears to be initially an in depth enquiry and I am surprised that no one was informed about its being before its conclusions were made public. Not usually how things work. No doubt in time it might be be found to have some flawes but at this moment in time it speaks well of the intent to reduce deaths and serious injuries and I would agree that such a scheme may indeed do that. The saving of one life outweighs all of the the cost of its implementation, of that there is no doubt.

    I am in no doubt also that Bristol Council must feel some degree of satisfaction as to the results of the enquiries and examinations Made by Bristol University that have vindicated their adoption of the scheme and have highlighted the positive nature of their endeavours.

    bob craven
    Agree (6) | Disagree (6)

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