Bristol City Council and NHS Bristol are jointly piloting two large 20 miles per hour (mph) limits in parts of the city with higher health needs. As well as fewer injuries and deaths, other potential benefits could include more physical activity, less traffic noise and better air quality. These can lead to reductions in obesity, diabetes, heart disease and mental health conditions.
The Marmot Review ‘Fair society, healthy lives' states that: "targeting [20 mph] zones in deprived residential areas would help lead to reductions in health inequalities".
The link between people from poorer backgrounds and casualties from road accidents has been observed from at least as early as the 1980s - see the Black Report published in 1980 by the then Department of Health and Social Security. More recently, modelling 20 mph speed limits in London found that the number of casualties in the most deprived quintiles would be halved - a fall of 580 deaths annually.
The problems and how they were tackled
Active Bristol project is an ambitious five-year programme to reverse the decline in physical activity of the city's residents. Its partners identified a blanket 20 mph speed limit on residential streets as one of the main things they wanted to achieve.
City councillors - both the previous and current administrations - have authorised two large pilot 20 mph areas. With input from Dr Adrian Davis, Public Health Partner to City Development, the council used health inequalities data to select two areas to the east and south of the city centre.
The south Bristol pilot began in May 2010; the eastern area will start this autumn.
The approach will use a combination of speed signs, social marketing and communication. No physical traffic calming measures - such as chicanes and speed humps - will be installed.
The council and PCT put forward two reasons for this.
The first is cost. Even before the global economic crisis and UK recession they had identified that money simply would not be available to install physical traffic calming devices in all of the city's residential areas.
The second is that an approach based on culture change and underpinned by communications will, in the long term, mean that physical measures are not necessary. By providing people with factual information about why they are installing 20 mph speed limits and what the benefits will be, they hope to build on what they have already identified as strong public support.
Dr Angela Raffle, Consultant in Public Health at Bristol, says that:
"We are currently developing a really strong positive advocacy campaign to win hearts and minds both within public sector workforces and among the general public. There will be a need for enforcement, but this can most easily be achieved once there is widespread acceptance of calmer residential streets as a good thing."
The PCT and council are speaking with local police officers through neighbourhood partnerships to make sure that the new limits will be monitored. The Bristol Partnership - the city's LSP - is fully signed-up to 20 mph. The assistant chief constable of Avon and Somerset Police is a member of the partnership board.
Outcomes and impact
The first pilot is now being evaluated. This includes both measurements of whether or not people are keeping to the new speed limit and qualitative research with residents to gauge their ‘before and after' views on the limits.
To complement the pilots, the council and PCT have set up a knowledge transfer partnership with the University of West of England. This is exploring how the council can move away from a model that looks only at reducing the number of casualties and deaths from road accidents, which could, for example, be achieved by keeping children indoors, to an approach that is based on reducing road danger.
The results of the project are not yet published (September 2010), but it will suggest a number of practical measures. For example, traffic authority approvals (TAAs) are circulated internally as part of the consultation on new traffic schemes.
The simple form gives officers an opportunity to comment on the proposed scheme. In future, the project is recommending that the TAA form should include the following questions:
- Does this scheme promote walking or cycling?
- If so, how?
- If not, why not? And why should it still be approved?
The purpose of these questions is to help change the transport engineering culture. This traditionally has prioritised motor vehicle use and flows ahead of any broader understanding of the health impacts of failing to provide for active travel modes.
For example, research has found that there is a significant association between commuting to work by car and being overweight or obese, compared with active travel modes and using public transport.
The second pilot area is scheduled to begin in autumn 2010.
Timescales for monitoring and evaluation are still being developed. But it is likely that councillors will make a decision on whether or not to roll out a blanket 20 mph speed limit in residential areas by the middle of 2011.
The communications teams of the PCT and council are developing a joint campaign to highlight the benefits of 20 mph limits where people live. It will emphasise that the limits will help to make streets pleasant, safe and friendly.
The approach will draw on the following evidence:
- reducing speeds to 20 mph won't affect journey times
- a child hit by a car at travelling at 40 mph has an 85 per cent chance of dying - if they are hit at 20 mph that risk plummets to five per cent
- lower speeds reduce air and noise pollution
- public support for the new speed limit is very strong - the local ‘Twenty is Plenty' campaign is backed by all of the organisations that make up Bristol Partnership, Living Streets, Streets Alive and Sustrans.
The campaign will target both the public and the workforces of the council and the PCT. Staff behaviour change alone could have a significant effect. Community nurses drive an average of 3,500 miles a day on Bristol roads. By setting an example and driving at 20 mph in the pilot limits they could act as ‘pace cars' and help other drivers keep to the speed limit too.
Matthew Nye, a manager within Bristol Community Health, says:
"Our core values are all about health and health inequalities so our staff should be leading the way on making Bristol a safer, healthier city for everyone".
If the pilot results echo research and practice elsewhere then the potential for improving health and reducing health inequalities is promising. The innovative aspect - and the big unknown - is whether a combination of speed signs and social marketing and information support will be enough to change behaviour in two ways: reducing the speed at which individuals drive, and encouraging them to consider using active travel modes (walking, cycling and public transport).
Costs and resources
The 20 mph pilot limits are costing £430,000 to implement, which is being spent on signage, vehicle-activated warnings, traffic regulation orders (TROs) and evaluation. The budget for the accompanying communications strategy is not yet fixed.
How does this compare with a speed reduction programme that would also have installed traffic calming measures? Davis argues that the figure for the current approach is likely to stay in the "six figures", but installing traffic calming throughout the city would have cost "millions and millions".
The knowledge transfer partnership included £20,000 from the PCT and £15,000 from the council.
The pilot speed limits are part of a wider approach to embedding a healthier transport system across the work of the council and the PCT. Under the joint director of public health, Bristol has a Healthy Urban Team that includes a senior planner, a public health specialist and other cross-cutting experts.
Despite this, Raffle says they face "an uphill struggle". She warns that widespread 20 mph speed limits are likely to be opposed by the motoring lobby. There is also a danger of ‘reverse Nimby-ism': people will want cosy 20 mph limits for their streets while still expecting to drive somewhat faster down other people's.
Slowing down vehicles to protect people from the harmful consequences of motor traffic may lead to improvements in the places where people live. One consequence could be an increase in cycling and walking, less car use, more use of car clubs and, perhaps, fewer cars.
Ultimately, though, she is upbeat:
"If we get a culture change on speed then it will be like it was when the smokefree legislation was introduced: people will say ‘why did we wait so long to transform our streets where people live?'"
Contacts and links
Dr Adrian Davis
Public Health Support to City Development
Bristol City Council
Telephone: 0117 9036731
Dr Angela Raffle
NHS Public Health Partner to Bristol City Council
Health, Climate Change and Peak Oil
Telephone: 0117 900 2655
The role of infrastructure and town planning in health improvement - interview with Adrian Davis in 2009
Is speeding a ‘real' antisocial behaviour? A comparison with other antisocial behaviours, Poulter D and McKenna F (2007). ‘Accident Analysis and Prevention', 39: pp 384-389