Modeling And Studying The Control Method Of The Combined Bottleneck System

As one important aspect of traffic bottleneck, the combined traffic bottleneck influences the traffic congestion and traffic safety seriously. In china, the bus stop with its neighboring on-ramp and off-ramp constitutes a typical combined bottleneck. Thus various vehicles will inevitably interweave each other when passing through. In this work, the combined traffic bottleneck effect of the bus stop, the on-ramp and off-ramp is discussed, and the control method is proposed to relieve traffic congestion near the bottleneck. The main contents are given as follows:1. The combined traffic bottleneck effect of the bus stop, the on-ramp and off-ramp is discussed by modeling traffic system in a two-lane cellular automaton model. We analyze cogestion mechanism between these three bottlenecks and summarize the reasonable setting way of the bus stop and the ramp. The results suggest that the setting way (Case B) that the off-ramp is set at the upstream of the bus stop and the on-ramp is set at downstream of the bus stop is better than the setting way (Case A) that the on-ramp is set at the upstream of the bus stop and the off-ramp is set at downstream of the bus stop. The setting way of Case B can reduce the combined traffic bottleneck effect, enhance the road capacity and the utilizing efficiency, and reduce the negative effect.2. According to the traffic congestion mechanism, we put forward the control method of the combined traffic bottleneck system constituting of the bus stop and the on-ramp. For the system that the on-ramp is at the upstream of the bus stop, we propose the average spacing feedback method. The results suggest that it can enhance the upstream flux of the main road, improve the traffic condition of the main road, but causes slightly reduce of downstream flux of the main road. For the system that the on-ramp is at the downstream of the bus stop, we propose an acceptable space merging control method. It can enhance the upstream flux of the main road slightly. Furthermore, we find the methods based on the traffic congestion evolution mechanism are more effective, compared with other control method.3. The average spacing feedback method based on congestion mechanism is applied on the Case A system. The results show that it can also improve the upstream flux of main road, and improve the traffic condition of the main road. Further we compare the method based on congestion mechanism with other control method, and find it is more effective. In addition, the acceptable space merging control method is applied on the Case B system. The results show that the system flux and the traffic condition have almost no change, after adopting the method. If adopting the traditional control method, the system flux will reduce and the traffic condition will become worse, while adopting our control method can enhance the traffic system safety.