Burnout Paradise: Lewisham sticks with 30mph

In March, Islington will introduce 20mph speed limits to all of its main roads. Greenwich and Hackney are doing likewise. The aim is to reduce the number of people killed on London's roads each year.

The Economist says:

Slower roads appear to be safer. A paper published in the British Medical Journal looking at accident data from 1986 to 2006 gave London’s 20mph zones credit for a reduction in casualties by 42%. Accidents that do happen at slower speeds are less harmful: the Transport Research Laboratory found that approximately 98% of pedestrians will survive a 20mph collision. Their chances drop to around 93% at 30mph and 69% at 40mph.

Lewisham recently turned down a suggestion by Cllr Darren Johnson that the borough introduce a 20mph limit to Lewisham's main roads on the grounds that such a limit would be practically unenforceable. The question is, whether limits work without enforcement - whether it's enough just to tell people to slow down? As the Economist reports, the average road speed in Portsmouth dropped by 1.3 mph as a result of the new rules. Given that an unenforced scheme costs little, is a small drop like this a success or a failure?

If you spend most of the time crawling through London in a car anyway, having to stick to 20mph when you hit relatively open roads is maddening. But faced with the road death statistics, it's hard to argue against a lower limit.