Research On Signal Control Optimization Model On Urban Road Traffic Under Mixed Traffic Condition

The optimization design of signal timing parameters is an essential part of the traffic signal control system for urban road. It is a very important and complex practical problem, involving assignment of the right of way and traffic benefits. Mixed traffic is the typical characteristic in urban road in China, which reduces the operationality of traffic organization optimization management. Therefore, it is necessary to carry out further study on traffic signal control design under mixed traffic condition in urban road, in order to provide solution for alleviating traffic congestion and creating safe and comfortable travel environment, as well as to provide a theoretical basis for developing traffic signal control system under mixed traffic condition in urban road.Based on the operating characteristics and constitutions of mixed traffic flow in urban road, the impacts of mixed traffic flow on the signal control system are generalized into two categories:(1) unreasonable assignment of the right of way between the intersection of motor vehicles and slow mode transportation, and (2) interference from mid-block street crossing signal on the traffic flow. According to the principle of traffic control, using the idea of "co-existence between motor-vehicle and slow mode transportation", this dissertation presents three types of traffic control problems under mixed traffic condition,(1) The whole optimization control method of multi-transportation at intersection;(2) Signal coordination control optimization method of mid-block street crossing and intersections;(3) Multi-objective area coordination control method under mixed traffic condition. These three collective problems, from different aspects, explore progressively signal control plan for the typical mixed traffic in China, forming a point-line-surface structure of signal control plan problem.The main scientific research work and results are:1. For considering the equilibrium benefits of motor vehicle and slow mode transportation, this paper presented the multi-objective optimization method of signal timing parameter at intersection by analyzing the influences of the composition of mixed traffic at intersection on traffic control. Then, the weight coefficients of control performance indexes were calculated by the mixed ratio of vehicle and slow mode transportation. Furthermore, taking intersections of different mixed traffic structure for example, this study provided simulation experiment of multi-objective optimization model. The results of actual calculation indicate that the model is feasible and is more suitable for the signal control intersection which has the higher mixed ratio of slow mode transportation.2. Through analyzing the two-phase signal control intersection with two phases which have large different road level and heavy pedestrian traffic flow. Being green time in non-critical phase is shorter and the lane of critical is wider, the pedestrian can't be crossing in one time. Then, a new control method was introduced for the intersection by modified the pedestrian phase based on the ideas of motor vehicle signals which control pedestrian simultaneously. Furthermore, pedestrian control delay calculation model was established, as well as the signal timing parameters optimization model was presented. From the results of a comparative case study with real world traffic flow data in Beijing, the new method is better effectiveness in heavy pedestrian traffic flow of secondary road.3. By analyzing the impact on mid-block street crossing to the control system at adjacent intersections, this study tested and verified the necessity to research on the signal coordination control optimization method of mid-block street crossing and intersections. This paper focused on the research of signal timing parameters optimization of mid-block street crossing and intersections according to the coordination control theory. Considering the discreteness of motorcade, delay model of vehicles was introduced. Then, split and offset common optimization model of intersections and the split optimization model of mid-block street crossing were proposed. The system composed of mid-block street crossing and intersections is taken for example to simulate in the single-point control at intersection, coordinated control without mid-block street crossing signal and the coordinated control method presented in this paper. The results show that the new method is feasible and the indexes are increased gradually according to the order of "coordination control in this paper"—"signal control for single intersection"—"coordination control without mid-block street crossing". The necessity of the research on coordination control of mid-block street crossing and intersections is proved again.4. To research on area coordination control signal timing parameters optimization method under mixed traffic condition, the traffic zone division method was given from qualitative point of view. Considering the impact of slow mode transportation's short distance travel characteristics on area coordination control, the paper established the multi-objective bi-level programming model for common cycle time and split. The offset optimization model was designed by using constraint condition of vehicle average travel time under single-point control program. By comparing with practical investigation data in Beijing, transport network capacity and delay of travelers are improved with the area coordination control method in this paper.