Setting of Outside U-Turn Waiting Area at Signalized Intersections of Main and Auxiliary Roads

Due to differences in land utilization, some intersections are separated into main and auxiliary roads. A left-turn lane on the outside auxiliary road must be set to ensure normal access of the left-turn and U-turn vehicles on the auxiliary road. However, conflicts will generate between the left-turn vehicles on the inside main road and U-turn vehicles on the outside auxiliary road. We propose a method for setting the outside U-turn waiting area with signal planning. This method includes three parts: Determination of the location of the U-turn waiting area, signal planning scheme, and spatial scheme. We used VISSIM to verify the effectiveness of this method. The simulation results show that the delay and the average queue lengths of the intersection can be greatly reduced after applying the method, and the reduction can reach 25-30% when the arrival rate of the outside U-turn vehicles ranges 120 to 180 vehicles/h.