Babies and children * Young people * First aid

20mph speed zones cut injuries by 40%

20mph speed zones reduce casualties by 40 percent Biggest drop seen in children

The introduction of 20mph speed zones in parts of London has reduced road injuries by 40%, according to a new study.

The speed zones have been particularly effective in cutting deaths and serious injuries, and in reducing the number of child victims.

The study, published in the British Medical Journal's website, estimates that 203 casualties are prevented each year. If the zones were to be extended to all of the London area, then this estimated reduction rises to 692.

The researchers, from the London School of Hygiene and Tropical Medicine, looked at the effects of 20mph speed zones over the last 20 years in the London area. By linking geographically coded police data to detailed information about London's roads, the found that 20mph zones had 40% less casualties and collisions than other roads.

The number of children killed or seriously injured was reduced by half, with overall pedestrian injuries reduced by around a third and cycling casualties reduced by nearly 17%.

The reductions were even greater in younger children (those under 12) and for the most serious injuries.

Even roads just outside the 20mph zones recorded a reduction in casualty rates of 8% on average.

"The additional effect of the 20 mph zones was that of a step reduction in casualties and collisions by an amount that has taken over 20 years to achieve on roads without 20 mph zones" the authors said.

"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," the authors concluded.

This article was published on Fri 11 December 2009

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