Accident Analysis for Horizontal Curves of Two-Lane Rural Roads

Abstract

On two-lane rural roads in Thailand, curve segments are among the most hazardous locations leading to road traffic accidents, which need an urgent action to reduce accident frequency and severity. In general, horizontal curve segments can be classified into four types: a circular curve, a compound curve, a reverse curve, and a broken-back curve. For each type of horizontal curve, the risk of accident occurrence and its safety treatments are varied. The focus of this paper is two-fold. First, this study classified horizontal curve segments on two-lane rural road network by curve type using alignment data from GPS vehicle tracking system. Second, the study conducted accident analysis to examine the relationship between road attribute and accident data for each curve type using 3-year historical accident data. The results from the analysis indicated that the types of horizontal curve segments affect fatal and severe injury accident rates; accidents involving motorcycles have the highest accident rate on broken-back curves, while accidents involving cars have the highest accident rate on reverse curves.