bicycling

In the United States a frequent source for cycling-infrastructure design is the American Association of State Highway and Transportation Officials’ Guide for the Development of Bicycle Facilities. In its current form, the guide favors one-way bike lanes separated from vehicular traffic by painted lines; cycle paths at sidewalk level are discouraged and physically separated two-way paths, known as cycle tracks, are not mentioned.

By their very nature, city streets are filled with a broad spectrum of users, from children walking with their parents all the way up to tractor-trailer trucks, which can weigh 80,000 pounds or more. With such an immense disparity in size, those outside motorized vehicles are the ones most likely to suffer in a crash — in 2008, more than 5,000 pedestrians and cyclists were killed by vehicles in the United States, and more than 120,000 were injured.