The Optimal Design of U-Turns on Thai Highways

Abstract

The purpose of this study is to evaluate optimal layout design of U-turns on basis of road safety for highways of Thailand. In Thailand, U-turns are one of major segments of highways after intersections, contributing to rural highway crashes. Different layout designs of U-turn and variation in its elements are influencing factors for drivers’ expectance and causing confusion in drivers. Therefore, the evaluation of layout designs of U-turn of rural highways is important to reduce future crash rates. For this research, initially the ‘accident based investigation’ was considered, the accident cost rates for different layout designs was planned to be evaluated. But due to underreporting of accident data in various agencies in Thailand, the ‘accident based investigation’ could not produce reliable results, so ‘event based investigation’ is considered for further study. For ‘event based investigation’ study the ‘traffic conflict technique’ is planned to use.