Coordinated Control Of The Adjacent On And Off Ramp And The Intersection In Urban Elevated Road

The on-ramp and off-ramp of urban viaduct is an important hub connecting the ground road and the elevated road. During the peak period, the vehicle is too much, which often makes it become the physical bottleneck of the elevated road. When the intersections are associated with the ramp, traffic congestion is more serious, which is mainly shown that the vehicle of the on-ramp can not go up or the off-ramp can not go down. As it is difficult to rebuild the ramp, the reasonable management and control method is of great significance to improve both the traffic jam and the efficiency of the operation.In this paper, massive domestic and foreign reference is read. On the basis of previous studies, the coordinated control method of the on-ramp and the off-ramp with each other intersection is put forward respectively. The mainly following workings are as followed.(1) To the on-ramp control, the operation characteristics of the regional traffic flow of the main line of the elevated road, on-ramp and the intersection area on the ground are analyzed, the traffic flow mechanics model of the entrance ramp and main line is deduced in detail.The effect of intersection upstream to on-ramp and elevated road is considered, and then the improved traffic flow model is got by analyzing the source of the on-ramp vehicle. Finally the coordinated control of the on-ramp and the adjacent intersection is realized, according to adjusting the mediation of on-ramp rate with using the MIXED-CONTROL algorithm to the system error minimum as the goal.(2) To the off-ramp control, firstly, the intersection of Chengdu City, two ring road south of four street and hongpailou and its relationship to the exit ramp is taken as an example, the operation characteristics of the regional traffic flow of the main line of the elevated road, off-ramp and the intersection area on the ground are analyzed by collecting the peak hour traffic data. Then the ramp and ground cross different traffic flow are given off taking use of the control variable method to analyze the impaction under the combined action of the two on the main road through the VISSIM simulation, which leads to the method to deal with the off-ramp and its intersection connected coordination control. According to the principle of fuzzy control, a fuzzy controller with two levels is designed. The first level fuzzy controller used to get the green light to extend the time based on the green phase detection to the intersection of the imported vehicle congestion index and difference of the red phase traffic congestion index; the second level fuzzy controller is used to get the green light time correction according to the green phase detection to the vehicle arrival rate and the red phase upstream section traffic jam density.(3) In this paper, for on-ramp and its link intersections, MATLAB is made use of for on-ramp control algorithm programming, and the timing control, alinea control and coordination of the design of the control algorithm of the control effect are compared based on VISSIM simulation to prove the validity of the control method; for the off-ramp and its intersection interfaced, first the VISSIM is secondary developed, and then the current control scheme under the running state of the vehicle is simulated through the preset simulation environment and simulation data, finally the design of fuzzy control and timing control strategies control effect are compared and analyzed to verify the validity of the model.