Study On Conflicting Traffic Flow Of Two-phase Intersection Based On Cellular Automaton

The intersection is an important traffic bottleneck in the urban road traffic network.It brings together the conflicts of motor vehicles,non-motor vehicles and pedestrians in all directions,which directly affects the operation efficiency of the entire road network.Intersection signal control is the main method to resolve conflicts.It can separate conflict traffic flow in time and space.However,due to the limitation of basic conditions such as terrain,there are still a large number of two-phase intersections in China.The phase setting of the two-phase intersection is simple,and the motor vehicles,non-motor vehicles,and pedestrians share a phase,and the traffic conflict is particularly serious.Especially,the traffic conflicts frequently occurred between the left-turning motor vehicle and the straight-through vehicles and pedestrians during the turning process.It has a great impact on the operating efficiency.According to the prevailing rules,left-turning motor vehicles should be allowed to yield when they encounter straight-moving motor vehicles or pedestrians.In real life,a left-turning motor vehicle is driving freely in the intersection,and the phenomenon of looting is everywhere.This phenomenon causes the traffic at the intersection to be chaotic,which not only brings great security risks,but also may reduce the traffic capacity of the intersection and increase the delay time of vehicle.Aiming at this phenomenon,this thesis constructs a conflict model of left-turning vehicles,straight-through vehicles and pedestrians at two-phase intersections based on the cellular automaton model,and analyzes the traffic flow conflicts characteristics of such intersections.It can provide a reference for developing intersection management control measures and improving the service level of intersections.The research contents and main conclusions of this dissertation include:(1)Construction and analysis of conflict models for left-turning vehicles and straight-through vehicles at two-phase intersectionsFirstly,the Nasch model is used to construct the left-straight motor vehicle conflict model of the traditional method which fixes the path and supposes that all left-turning vehicles yield the straight-through vehicles.Then,according to the phenomenon that the direct-going motor vehicle does not have the priority right-going right and the left-turning vehicle is driving freely in the intersection,a conflict model considering the left-turn vehicle preempting behavior and two left-turn vehicle running paths is constructed.It makes the model more realistic.The two models are simulated by MATLAB.The influence of the arrival coefficient of the motor vehicle on the flow of the intersection and the operation of the motor vehicle is compared and analyzed.It is found that the preemption of left-turn vehicle is beneficial to the traffic of the left-turning vehicle,but it greatly hinders the straight-through vehicle.Preemption leads to a 1%to 15%reduction in traffic capacity at the intersection.(2)Construction and analysis of the conflict model of left-turning vehicles and pedestrians at two-phase intersectionsOn the basis of considering the left-turn-direct vehicle conflict model of rushing,the pedestrian interference factor is considered,and the conflict interference model of left-turning motor vehicles and pedestrians at the two-phase intersection is established.In this paper,the pedestrian's update rule uses the lattice gas model to couple the pedestrian cellular automaton model with the vehicle cellular automaton model.Through MATLAB simulation,it is found that in the case of cross-street pedestrian interference,the capacity of intersections with preempting left-turning cars is further reduced by 10%to 25%.