A study of Conflict Analysis at U-turn with and without auxiliary lanes : A case study of median width not more than 3 meters.

Abstract

The purposes of this research were to compare conflict of U-turn traffic at U–Turn locations with and without auxiliary lanes. In this study, the width of the road median is not more than 3 meters. This research collected the traffic data on route No.1 (Phahonyothin), under the supervision of the Office Of Highway 11 (Lopburi). Two U-turns were selected in this study. The U-turn located at Sao-Thong market and the second branch of Big C Lopburi. The data on traffic condition and problems at both U-turns were collected for two days of workdays between 06.30-08.00 AM. and 3.00-4.30 PM. They were used to develop the traffic micro-simulation models using the VISSIM software. This research developed nine traffic micro-simulation models and the traffic conflicts were analyzed by using the SSAM program. The important variables were level of service, queue length, traffic volume, average delay and time-to-collision. This study found that adding auxiliary lanes to the U-turn resulted in decreasing of U-turn accidents, rear-end accidents, and average delay, which might improve the level of service. In addition, the increased length of auxiliary lanes also resulted in decreasing of rear-end accidents.