Traffic Calming

Traffic calming slows the speed of motorised traffic and thus reduces the speed differential between vehicles and cyclists and pedestrians – creating a much safer environment for everybody!

Denmark 026 Traffic CalmingRead about the traffic calming experience in Munich (courtesy of Via Stada’s Axel Wilke Velocity 2007 report):

When Germany introduced legislation in the mid 1980s that allowed cities to drop urban speed limits to 30 km/h, Munich started the process of introducing those zones in 1988. The conversion has by now finished, and of the 2,300 km of urban road network, 80% are now covered in 333 individual 30 km/h speed limit zones. The remaining 20% represent the main road network, where the default speed limit is 50 km/h. New subdivisions are automatically built with a 30 km/h speed limit.

Munich’s ultimate cycle network is 1,400 km long, of which 1,200 km have been built already. 38% of the existing network is within 30 km/h zones. When streets are reconstructed and the speed limit reduced, it is Munich’s policy to remove existing cycle paths or cycle lanes (if these are present), as mixed traffic is by far the safest form of travel for cyclists. The person responsible at the city for the implementation of the cycle network used the following words: “The best and safest cycle path is, ultimately, the one that is not needed because of the traffic structure and the traffic proficiency of the road users.“

It’s possible to do the same thing in New Zealand, it helps to strengthen communities, improved retailing and has strong support amongst residents, eg the Pt Chev SALT survey of residents.

It’s legally possible, see the enabling regulation legislated in 2003: http://www.landtransport.govt.nz/rules/setting-of-speed-limits-2003.html Section 3.2(5) of the rule allows local councils freedom to set appropriate speed limits, eg 30km/h in residential, retail and employment neighbourhoods.

The Dutch cycle design code (Design manual for bicycle traffic, English version 2007) gives speed hump designs for 20, 30, 50 and 60 km/h. All except the 50 km/h (which is a speed table) are a sine-wave design with a common height of 120 mm and lengths of 3.4 m for 20 km/h, 4.8 m for 30 km/h and 12 m for 60 km/h. A cyclist’s bypass is possible (minimum width 1.2 m, preferred 1.5 m) but not essential.
The hump is designed to give all vehicles a smooth ride if they are travelling at or below the design speed. If anybody goes too fast the bump comes on landing.
It would be easy enough to make a template so that road builders could get the shape right but a precast concrete hump might be easier.

A 1980′s banner from the Dutch cycling advocates’ campaign: “50 is too fast!”

calmin1 Traffic Calming

See a succinct explanation of Traffic Calming in Bevan Woodward’s paper “Area-wide Reduced Traffic Speeds: Benefits and barriers”

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