As the Olympics drew to a close last weekend and attention turned to the need for a lasting legacy of improved access to sport and active lifestyles, some newspapers were at the same time reporting that 20mph limits are ‘not working’. These reports focused on the fact that casualties have gone up across all 20mph limit roads in 2010-11, strangely overlooking that 20mph limits have become significantly more widespread during this period.
We don’t know precisely how extensive 20mph limits now are, because unfortunately the government doesn’t monitor this, but we do know more and more city, county and borough councils are deciding to implement 20mph limits across most or many of their built-up streets, including Portsmouth, Liverpool, Bristol, Oxford, Edinburgh, Brighton, Lancashire and Islington. Clearly, as we bring in 20mph limits across far more of our road network, it’s likely an increasing proportion of road casualties will occur on this type of road. In 2010-11 serious casualties among pedestrians and cyclists, which mainly happen in built up areas, went up overall. It does not follow that 20mph limits don’t work, although it does indicate that far more should be done to make walking and cycling safer.
In fact, the evidence is quite conclusive on the safety benefits of lower speeds in communities. There is a very well demonstrated link between traffic speed and safety: unsurprisingly, if you slow traffic it results in fewer and less severe casualties . Numerous studies have shown that 20mph limits result in casualty reductions, especially among people on foot and bicycle .
The reason we believe 20mph is a more appropriate limit for built up areas is down to the huge difference in stopping distances (it’s almost double at 30mph compared to 20mph), and therefore drivers’ ability to react and avoid hitting someone. If a child suddenly steps out three car lengths ahead, at 20mph you should just be able to stop in time. But at 30mph you’ll hit them at almost full speed and have a significant chance of seriously injuring or even killing them .
The other critical component in the case for 20mph limits is the fact that danger from fast traffic is a major barrier in people choosing walking and cycling as a healthy and sustainable mode of travel, and in families and kids feeling able to get out and about for leisure and exercise. In surveys, a huge proportion of people say they’d walk and cycle more if it was safer . At the same time, three-quarters of people (74%) support use of 20mph limits on residential streets . In short, people are crying out for slower speeds and safer streets to enable them to walk, cycle, run, socialise and get about without being endangered.
Making our streets safer is fundamental in creating healthier, happier and more active communities - and 20mph limits across our towns, cities and villages are an effective way to help bring this about. After the inspirational Olympic performances of runners, cyclists, triathletes and many other sportspeople who use local streets as their training ground, this is surely a key part of the legacy we should all be getting behind.
 For example Speed and Road Safety: Synthesis of Evidence from Evaluation Studies, Transportation Research Board of the National Academies, 2006, and The effects of drivers’ speed on the frequency of road accidents, Transport Research Laboratory, 2000
 For example, 20mph speed reduction initiative, The Scottish Executive, 2001; 20mph Speed Limit Pilots Evaluation Report, Warrington Borough Council, 2010; Safety effects of speed reducing measures in Danish residential areas, Danish Council of Road Safety Research, 2002
 Typical stopping distances, The Highway Code, 2011
 Brake and Bolt Burdon Kemp surveys of commuters and parents on cycling, 2012 and Brake and Churchill survey of parents on walking, 2012
 British Social Attitudes Survey, 2011