IDENTIFICATION OF SEVERE CRASH FACTORS AND COUNTERMEASURES IN NORTH CAROLINA

This report examines the roadway, crash, vehicle, individual and environmental factors that are associated with fatal and serious injury crashes in North Carolina between 1993 and 1997. The initial analysis identifies road classifications, geographic characteristics, and time trends related to severe crashes using Highway Safety Information Systems (HSIS) segment and crash data. HSIS system highways in North Carolina included the state primary and major secondary routes. Non-HSIS roads include local streets and minor secondary streets. Both HSIS and non-HSIS data are used in the more detailed section of the study to analyze the severe crash factors on all HSIS highways, two-lane urban HSIS highways, two-lane rural HSIS highways, urban non-HSIS routes and rural non-HSIS routes. In this report, a test of the standard error of a binomial proportion is used to find the statistical significance of the roadway, crash, vehicle, individual and environmental factors related to severe crashes. The initial analysis shows that urban and rural two-lane roads are associated with the highest crash severity, mountain counties have the highest proportion of severe crashes and crash severity remained stable for some of the most severe crash types. Factors associated with significantly high crash severity on all roadway types include curve, run-off-road, utility pole, tree, head-on, pedestrian, bicycle, darkness and alcohol use. The final section of the report recommends countermeasures that can be used to reduce the incidence of fatal and serious injury crashes associated with these factors.