Publication Details

Identification of severe crash factors and countermeasures in North Carolina

Type: Paper

Subtype: Final Report

Author(s): Huang, Herman F.; Schneider, Robert J.; Zegeer, Charles V.; Khattak, Asad J.; Amerlynck, Virginie J.; Lacy, J. Kevin

Publisher: UNC Highway Safety Research Center


Publication Date: Aug-2001

Number: FHWA/NC/2001-003

Address: Chapel Hill, NC

Abstract: The eight Southeastern States in FHWA's Region IV have been ranked among the highest nationally in terms of fatal crash rates in recent years. These eight states include North Carolina, Alabama, Florida, Georgia, Kentucky, Mississippi, Tennessee, and South Carolina. These eight states accounted for approximately 25 percent of the nation's total fatalities in 1995 and a fatality rate about 20 percent above the national mean. In 1995, North Carolina ranked 9th of the 50 states in terms of total highway-related deaths, with 1,418 people killed. The fatality rate of 1.9 (people killed per 100 million vehicle miles of travel) ranked North Carolina 20th nationally. In response to these trends in traffic fatalities, the North Carolina DOT and other state DOT's in Region IV have expressed an interest in further studying fatal crash causes and possible countermeasures. The main objective of this study is to identify factors associated with fatal and serious injury crashes in North Carolina and recommend appropriate countermeasures to reduce their frequency. 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 include 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, 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.