Older Streets Are Safer Streets

Wes Marshall and Norman Garrick, after a study of data from 130,000 car crashes in California, have determined that cities built since since 1950 have more dangerous roads than those built before 1950.
January 30, 2009, 12pm PST | Tim Halbur
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"The newer cities tend to have more "dendritic" networks - branching, tree-like organizations that include many cul-de-sacs, limiting the movement of traffic through residential areas. They also don't have as many intersections. The pre-1950 cities, on the other hand, tend to be more grid-like, giving motorists many more routes to choose from.

For several decades, traffic specialists believed a tree-like hierarchy of streets was superior because it made residential neighborhoods quieter and presumably safer. But an American Society of Civil Engineers (ASCE) study cited by the UConn researchers points out that more-connected street networks tend to reduce travel speeds. That's important because even a small reduction in speed can boost safety - mainly by reducing the severity of the accidents.

A recent report from Europe found that when average vehicle speeds drop by just 5 percent, the number of injuries drops by 10 percent and the number of fatalities falls 20 percent. Extensively connected street networks may not have fewer crashes over all, but the crashes that occur are less likely to leave someone dead."

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Published on Monday, January 26, 2009 in New Urban News
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