Respect 20mph limit (From The Oxford Times)

Respect 20mph limit

8:00am Thursday 11th March 2010 in

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Sir– In your issue of March 4 you quote the chairman of the Oxford Group of the Institute of Advanced Motorists as saying that every piece of evidence in his possession shows that 20mph speed limits do not save lives. If he is seriously interested in evidence he clearly needs to widen his collection.

Last December the British Medical Journal reported a study finding that that the introduction of 20 mph zones in London over the years 1986 to 2006 was associated with a 41.9 per cent reduction in road casualties after adjustment for background time trends (BMJ 2009;339:b4469).

Studies included in the Cochrane Database of Systematic Reviews find that speed cameras are associated with reductions in collisions, injuries and deaths. These peer-reviewed reports in high prestige scientific publications are the best evidence on the link between attempts at lowering traffic speed and reductions in collisions and injuries.

In matters of public policy such as these, scientifically rigorous randomized controlled trials are not feasible and public authorities have to act on the best observational evidence available.

In the light of such evidence the county council displayed social responsibility in introducing Oxford’s 20mph limit, which socially responsible drivers will respect.

Sir John Grimley Evans, Professor Emeritus of Clinical Geratology, Green Templeton College, Oxford