Space Properties of the Road Alignment and Impact on the Traffic Accident

Based on numerous research works on road traffic safety, the space curvature index of expressway alignments was developed considering road alignment space geometric properties and its impact on traffic accident. This index was modified to reflect the influence of the curvature on highway operating speed. The road safety performance and operating speed of several expressways were investigated and the regression relationship between single-vehicle accident rate and space curvature index of highway alignments was studied. So that the space curvature index of highway alignments could be used as a prediction factor of traffic accident in highway alignments during highway alignment safety design and road safety analysis.