A Study on Operation Analysis of Permissive Left-Turn Signals in Korea

The left turn treatment at signalized intersections is becoming a topic according to government policy in recent times on Korea. There is an attempt to convert the traditional traffic signal system that allows drivers to make left turn under the left turn signal into permissive left turn under the straight signal. The authors analyzed and compared the effect of protected left turn and permissive left turn on specific conditions through case study and simulation As the result of analysis, the average delay was decreased on most cases after left turn phasing was changed from protected to permissive. The authors can say that the application of permissive left turn (according to the traffic condition) can increase effectiveness of traffic signals. Therefore, suitable left turn treatment that meets conditions and warrants is more important than anything. With results from analyzing various sites that applied permissive left turn signal in accordance with expanding permissive left turn traffic signals in Korea, the authors hope to solve problems in operation and to develop with studies on various left turn operation systems.