Thursday, May 20, 2004

Sharing Streets

The latest thing in urban traffic design is to get rid of traffic control altogether. That's right. No rules. Drivers have to slow down and actually watch where they are going.

"Research has shown that fatality rates at busy intersections, where two or three people were being killed every year, dropped to zero when controls and boundaries were taken away. "


Evidence from countries and cities that have introduced a design speed of 30 kilometers per hour (about 18.5 mph) -- as many of the European Union nations are doing -- shows that slower speeds improve traffic flow and reduce congestion.

"This surprises many people, although mathematically it's not surprising," Hamilton-Baillie says. "The reason for this is that your speed of journey, the ability of traffic to move smoothly through the built environment, depends on performance of your intersections, not on your speed of flow between intersections." And intersections, he says, work much more efficiently at lower speeds. "At 30 miles per hour, you frequently need control systems like traffic signals, which themselves mean that the intersection is not in use for significant periods of time. Whereas at slower speeds vehicles can move much more closely together and drivers can use eye contact to engage and make decisions. So you get much higher capacity."

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