Publication Information
Motor vehicle crash rates and roadway characteristics for National Highway System (NHS) and non-NHS roads in seven states-California, Illinois, Maine, Michigan, Minnesota, North Carolina, and Washington-are presented. Crash and roadway data were extracted from the Federal Highway Administration's Highway Safety Information System. Overall, crash rates on NHS roads were approximately 10 percent lower than those on non-NHS roads, perhaps the result of higher design standards. Crash rates on urban roadways were considerably higher than on the corresponding rural roadways in each state. For rural roadways, fixed object crash rates were higher on NHS roads. The distribution of crashes by severity was quite similar on NHS and non-NHS roads. The majority of NHS roads had lane widths of 3.4 m (11 ft) or more, and many had shoulder widths of 1.5 m (5 ft) or more.