Examination of Horizontal Curve Collision Characteristics andCorresponding Countermeasures

Horizontal curves are relatively dangerous portions of the roadway network. Agencies optimizing the use of their safety funds on curves should have an idea of the characteristics of the collisions that occur on those segments. However, few previous published papers had attempted to characterize the crashes on horizontal curves. This paper describes an effort that characterized crashes reported to be on curves in North Carolina using the Highway Safety Information System. The research compared crashes on two-lane road curves to crashes on all two-lane roads and to crashes on all roads. Since North Carolina has wide varieties of terrain, climate, and development, the findings should be generally representative of the US. The analysis revealed that over-represented two-lane curve crash types included: • Crashes on grades;Rural;Severe injury or fatal; Fixed object (particularly tree, ditch, and embankment); Overturn; Off peak hours (particularly during darkness on unlighted roads); Weekend; Holiday periods; and Wet, icy or snowy pavement. In addition, the analysis showed that there were few short roadway segments (of 0.1- to 1-mile length) with more than 10 reported curve crashes in 3 years. The paper provides a summary of recommendations from the national literature to treat the over-represented crash types. Based on the findings, agencies should target countermeasures for the most common and over-represented crash types. Agencies should also analyze longer segments to provide curvy segments with concentrations of crashes a chance to compete for funding with other types of segments.