Communities should be places where everyone can get out and about and feel safe, regardless of age, disability, or level of fitness. Everyone has the right to cycle, walk, run, or ride around their area and doing so has great benefits for the individual and the community. But often it just isn't possible for people to get out or feel safe where traffic travels faster than 20mph. That's why we support 20mph limits around homes, schools, shops, and communities. This fact sheet explains why slowing down to 20mph is so brilliant for our communities.

Road safety reasons:

Driving at 20mph or below gives a driver the chance of stopping in time if someone suddenly comes out into the road. Many drivers may think they will be able to stop in a similar amount of time if they are just going 'a few' miles faster – but sadly the physics of speed tells us they can't. For example, the minimum stopping distance you can expect if you travel at 20mph is 12 metres or three car lengths. Increase your speed to 30mph and the stopping distance is at least 23 metres or six car lengths – twice as far.

It's also worth knowing that a vehicle travelling at any speed will still have about 70% of its speed when it is half way through its braking distance. For example, if a car is travelling at 20mph, it will take at least 12 metres to stop as explained above. The first six metres will be taken up with thinking time. The next three metres will only reduce the speed to about 14mph. It's only in the final three metres that the speed significantly starts to drop and then the vehicle will stop. This means that if you decide to go faster and can't stop in time, you are likely to crash at a much greater speed than you might imagine. Here is a chart showing stopping distances at different speeds.

Health reasons:

When traffic is slower, people feel much freer to run, walk, cycle or take other activity. We all know how important it is to get regular physical activity: research has shown that half an hour of brisk walking a day can cut heart disease [1], and cycling and running are both really good ways to strengthen bones and lose weight [2]. On top of this, getting regular exercise has been shown to combat depression and other mental illnesses [3]. At a time of rising obesity levels and increases in physical and mental health problems across the country, 20mph limits are a really simple way to help us all to be healthier and happier.

Environmental reasons:

Driving at more than 20mph in towns and villages involves lots of speeding up and slowing down, increasing carbon emissions. By slowing down to 20mph in communities we can decrease the amount of carbon each car gives off [4], but we also make it safer for people to swap their car for a greener form of travel like a bike. This can have a really big impact on a community's carbon emissions, improving air quality and doing our bit for saving the planet.

Financial reasons:

20mph limits make our roads safer, so they reduce the number of crashes. As well as preventing the devastating impact such crashes have on people, this also has big financial benefits. Every fatal crash costs an average of nearly £1.7million pounds to the Emergency Services and to the economy [5]. There are also enormous financial costs to families when someone is killed or seriously injured, for example losing the main wage earner. So because slowing down to 20mph prevents crashes it not only protects people but it also saves money.

Community reasons:

When traffic is slowed to 20mph in communities, research shows people are likely to be more friendly with their neighbours, to feel safer in their area, and to take part in more community activities [6]. Research suggests that the more people feel connected to their local communities in this way, the better we feel and the healthier and happier we are likely to be [7].

Some research that helps prove the point

British drivers who speed are nearly twice as likely to have been recently involved in a road crash, finds research by the Scottish Government ( The Speeding Driver: Who, How and Why? (SG Stradling et al, Scottish Executive Social Research Findings No. 170/2003, 2003))

When Hull City Council introduced 20mph limits there was a 74% reduction in crashes involving child pedestrians in Hull in the three years after the introduction of the limits, compared to the three years before.

The transport research agency TRL, estimates that if average speeds are reduced by 1mph, crash rates can fall by an average of 5%.

Don't think that pedestrian protection measures or great brakes are the answer

It is often the case that pedestrian protection measures, such as 'pedestrian-friendly' bumpers, are mentioned in the same breath as car occupant protection measures. In many ways, these two sets of measures are not comparable. A vehicle occupant is in a contained space and can be protected by air bags. A pedestrian is outside and can fall in any direction, including under the wheels of a vehicle. To quote EuroNCAP, the crash testing agency: "although it is possible to control the point of impact of the bumper against the pedestrian's leg, it is impossible to control where the dummy's head will subsequently strike."

Development of pedestrian protection measures, particularly very soft ones such as exterior air bags and guards that prevent someone falling under a vehicle's wheels, are of some use. But there are so many variables for pedestrians in crashes that the effectiveness of such measures will always be variable. Such protection measures will be most effective at the very slowest speeds.

Better brakes can make stopping distances shorter, but there are a lot of things with a much more significant impact. Stopping distances can be affected by weight and loading of a vehicle, the maintenance and design of the brakes, drivers' reaction times, and weather conditions such as wet or icy roads or conditions that limit visibility such as fog or darkness. Anything we can do to decrease stopping distance so we can stop in time at any distance – whether it is driving slower or buying a car with modern brakes – should be done. We cannot rely on better braking technology alone to protect pedestrians.

The most important thing to remember

Committing to slowing down to 20mph is a really easy thing to do, but it can make a really big difference. Take the pledge today to show your commitment to saving lives on the roads.

Want to campaign for lower speed limits in communities? Go to Brake's campaign Slower speeds save lives

References

[1] Haskell,W. L., Lee, I. M., Pate, R. R., Powell, K. E., Blair, S.N. et al. "Physical activity and public health: Updated recommendations for adults from the American College of Sports Medicine and the American Health Association" Medicine & Science in Sports & Exercise,: 39:8 (2007)

[2] Marti, B. "Health effects of recreational running in women. Some epidemiological and preventive aspects." Sports Medicine 11:1 (1991)

[3] Mind: Ecotherapy: the green agenda for mental health, 2007

[4] Transportation Research Board, Expanding Metropolitan Highways: Implications for Air Quality and Energy Use - - Special Report 245, 1995

[5] Reported Road Casualties Great Britain, 2011. Department for Transport.

[6] Sauter, D., & Hüttenmoser, M., The contribution of public spaces to sical integration in urban neighbourhoods, Swiss Natural Science Foundation, 2006

[7] House et. al., "Social Relationships and Health", Science, 241:4865 (1988)