20 mph Zones

20 mph Zones

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Overview

20 mph zones are European neighborhood areas where vehicle speeds are limited to 20 mph, primarily to protect against child pedestrian injuries. London Mayor Ken Livingstone made the expansion of 20 mph zones a platform in his unsuccessful 2008 reelection campaign.[1]

Effectiveness

A study by the British Transport Research Laboratory of 20 mph zones across Europe found they reduced child pedestrian crashes by two-thirds, and bicycle crashes by 29%.[2] The Department for Transport recommends that newly applied 20 mph zones include traffic calming devices if the 85th percentile speed (the maximum speed at which 85% of traffic is traveling) is 27 mph or higher. Otherwise, drivers are unlikely to obey the speed limit without strict, consistent police enforcement - the sort few cities can afford.[3]

Child Crash Prevention a Public Health Issue

Traffic crashes are recognized as a major pediatric health issue worldwide, but most interventions are applied to children travelling as passengers in cars. Examples are infant and child carseat laws, and prohibitions against children riding as passengers in front seats where air bags are installed. In the U.S., virtually no physical protections are provided for children as pedestrians and bicyclists, outside of signage and specially marked crosswalks in school zones.

In July 2008, the British Medical Association called for the application of 20 mph zones throughout residential neighborhoods, not just in the vicinity of schools, where they are commonly applied.[4] Stockport public health director Dr. Stphen Watkins stated that "a child hit at 20mph has a 5% chance of dying compared to 50% at 30mph." He noted the differnce between a two mile journey at 20mph and a two mile journey at 40 mph was just three minutes. "We are killing our children for the sake of a couple of minutes," he said.

20 mph Zones Improve the Economy

The UK study of best traffic practices across the Europe and the U.K. concluded that 20 mph streets also increased pedestrian activity, bicycling, a sense of safety among residents, and economic activity. The study cited evidence from the city of Horsham, U.K., where 20 mph speed limits, along with a bypass road, public arts, gardens, and other pedestrian amenities have lead to the opening of new shops and restaurants, and a higher level of overall eoconomic activity.[2]