This site is intended for health professionals only

20 mph zones reduce road injuries

The amount of people getting injured on London roads has dropped by over 40% since the capital introduced 20 mph speed zones, according to a report.

Analysing statistics from 1986 to 2006, the study by the London School of Hygiene and Tropical Medicine discovered the zones had the most impact on young child accident rates and the number of deaths and serious injuries overall.

The report, published online in the British Medical Journal,  found casualties were cut by 41%, with deaths or serious injuries to children reduced by 50%.

In addition, pedestrian injuries were reduced by just under a third and cycling casualties by 16.9%.

The study suggested that 20 mph zones prevent 203 casualties a year. The case for extending the zones in London, with the potential of preventing a further 692 casualties a year, was supported by the report.

No evidence of "casualty migration" to areas bordering the 20 mph zones was found. In fact, in areas adjacent to the zones casualties also fell by an average of 8%.

The authors said: "The additional effect of the 20 mph zones was that of a step reduction in casualties and collisions. This evidence supports the rationale for 20 mph zones not just in major cities in Britain but also in similar metropolitan areas elsewhere. Indeed, even within London, there is a case for extending the currently limited provision of such zones to other high-casualty roads."

Copyright © Press Association 2009

British Medical Journal