Abstract
Concern over crashes involving bicycles and motor vehicles is largely due to the severity of injuries. The impacts of physical and environmental factors on the severity of injury to bicyclists are examined. North Carolina Highway Safety Information System crash and inventory data for state-controlled, two-lane, undivided roadways are analyzed. The injury severity distribution, measured on the KABCO scale, is as follows: no injury, 1.8 percent; complaint of pain, 24.4 percent; nonincapacitating injury, 42.5 percent; incapacitating injury, 25.5 percent; and fatal injury, 5.9 percent. The total number of involvements in this data set was 1,025, with a majority of the involvements occurring outside urbanized areas (80.5 percent). Using the ordered probit model, the effect of a set of roadway, environmental, and crash variables on injury severity is explored. Variables that significantly increase injury severity include straight grades, curved grades, darkness, fog, and speed limit. Higher average annual daily traffic, an interaction of speed limit and shoulder-width variables, and dark conditions with street lighting significantly lower injury severity. Separate models are estimated for rural and urban locations. Marginal effects of each factor on the likelihood of each injury-severity class are reported. Policy implications and possible countermeasures are then discussed.
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