Journal of Korean Society of Transportation ISSN:1229-1366(Print) 2234-4217(Online) 대한교통학회지

Many studies which considered volume and lanes of opposite straight traffic have been carried out to improve left-turn traffic flow at the signalized intersection. However, there were no studies reflect signal intervals which much influenced on the efficiency of the left-turn traffic flow. For the purpose of effective left-turn treatment, we considered signal intervals of the opposite straight traffic and left-turn traffic as well as the volume and lanes of opposite straight traffic. Based on the simulation results, left-turn delay of reduced significantly by the application of protected/permissive left-turn (PPLT) in case of congested left-turn traffic illustrated as left-turn signal time of 10 or 20second, but not as much as congested left-turn traffic in case of uncongested left-turn traffic such as left-turn signal time of 30second. Therefore, it is concluded that the heavier the left-turn traffic congestion, the greater the effect of protected/permissive left-turn (PPLT) in terms of reducing delay. Simulation results according to the variation of cycle length as well as the volume and signal interval of left-turn and opposite straight traffic can be used to find the best left-turn treatment among protected left-turn (PRLT), permissive left-turn (PELT) and protected/permissive left-turn (PPLT) at a signalized intersection.