Narrower lanes, fewer accidents

Wide traffic lanes may make traveling more dangerous, rather than less. Eric Dumbaugh at Texas A&M, who has studied road design and the frequency of accidents, has found that making traffic lanes wider than 11 feet does not improve safety. Crashes increase, Dumbaugh says, “as lanes approach and exceed the more common 12-foot standard.” Dan Burden at Glatting Jackson and Walkable Communities Inc. in Orlando concurs. Burden says that research by Robert B. Noland, examining 24 years of data on all roadway types in all 50 states, “concludes that 10-foot lanes for major roads (other than interstates) are safer than their wider-lane counterparts.” “The most serious injury-producing crashes” become scarcer when travel lanes are 10 feet wide, Burden says. “This is true for both urban arterial and collector roadways. It appears that as lanes become wider (above 10 feet), many motorists lose their vigilance.” These studies are consistent with a 1997 study done by Peter Swift and the City of Longmont, Colorado, that looked at injury accidents over an eight-year period throughout the city. The study concluded that the narrowest streets in the city are the safest. The study, which looked at 13 street design variables, found that injury accidents rose 485 percent as streets increased in width from 24 feet to 36 feet. The most dangerous streets in the city were 50 feet wide. The study is available online: massengale.typepad.com/venustas/files/SwiftSafetyStudy.pdf