- Bicycle Culture by Design: 30 km/h Zones Work

As it turns out, I didn’t get my christmas wish fulfilled. 30 km/h zone for motor vehicles in Copenhagen. Maybe the package is still in the post, but it isn’t looking good here in mid-January.

Since wishing for 30 km/h zones - 20 km/h for school zones - there has been a bit of buzz about them. Barcelona is developing more 'Zones 30' based on positive results. A 27% reduction of accidents in one area of the city, for example.

Amsterdam has proposed a similar scheme, too and the Dutch Fietsersbond advocates them. The list of cities and towns lowering the speed limits is growing across Europe week by week.

In an inspired moment of excellent timing, The British Medical Journal published a paper about the effect of 20 mph traffic zones on road injuries in London. It was written by researchers at... The London School of Hygiene and Tropical Medicine... which is strange, but hey.

Effect of 20 mph traffic speed zones on road injuries in London, 1986-2006

Results: The introduction of 20 mph zones was associated with a 41.9% (95% confidence interval 36.0% to 47.8%) reduction in road casualties, after adjustment for underlying time trends. The percentage reduction was greatest in younger children and greater for the category of killed or seriously injured casualties than for minor injuries. There was no evidence of casualty migration to areas adjacent to 20 mph zones, where casualties also fellslightly by an average of 8.0% (4.4% to 11.5%).

Conclusions: 20 mph zones are effective measures for reducing road injuries and deaths.

Hang on... did they just say that we have an effective measure for reducing road injuries and death?! What are we waiting for then?

In this BBC article
, study leader Dr Chris Grundy, a lecturer at the London School of Hygiene and Tropical Medicine, said: "

This evidence supports the rationale for 20mph 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.

" He estimated that 20mph zones in London save 200 lives a year, but this could increase to 700 if plans to extend the zones were implemented. Talk of 30 km/h zones is often associated with quiet residential areas, which is fine and logical. I'm looking forward to seeing them in place all over Copenhagen and Frederiksberg. These zones are most effective in densely populated urban centres. We have a new city council here in Copenhagen, and a new Mayor in charge of the traffic department. Here's hoping that the bicycle/pedestrian visionary-ness of the past four years continues.

This graphic is from this article on SF Streetsblog shows how big a difference speed makes.

Even the Danish Road Safety Council, in their usual [and tiresome] 'try and scare the shit out of them' style which really is soooo last century, have previously tackled the speed issue with their "Take the edge off your speed" campaign. The caption reads "what's your pain threshold?" [an odd campaign, by the way... who are they speaking to? Motorists or pedestrians? Isn't quite clear.]

Tom Vanderbilt has a write up about this 20 mph/30 km/h business on his always excellent 'How We Drive' blog here. He mentions a website called Twenty's Plenty. A group in the UK who are fighting for lower speed limits.

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