| Intersections connect road to form a network,which is an important part of the urban transportation network.Traffic behaviors such as conflicts,merging,and diversion between traffic flows caused by the turning of vehicles make the traffic characteristics of intersections more complicated.Based on the cellular automaton,the paper conducts an in-depth study of the left-turn traffic flow on the main road at unsignalized intersections,builds an intersection model that meets the actual traffic characteristics,analyzes the impact of left-turning vehicle driver driving behavior on the intersection traffic flow,and explores in depth the operation mechanism of traffic flow at unsignalized intersections,enrich the theoretical research on traffic flow at unsignalized intersections,and provide decision-making reference for improving the capacity and safety of unsignalized intersections.The main work and research results of this paper are as follows:Select appropriate unsignalized intersections for data investigation.Analyze the basic composition of the selected intersection,use video shooting to analyze the driving behavior of the left-turning vehicle driver on the main road at the intersection,perform statistical analysis on the vehicle speed on the main road section and entrance of the intersection and the traffic volume of the main road at the intersection through data collection.Provide data for subsequent model establishment.Based on cellular automata,a traffic flow model of unsignalized intersections is constructed considering the different left-turning driving behavior of drivers.By analyzing the driving behavior of the driver when the vehicle turning left on the main road passes the intersection,it is divided into conservative driving behavior,stable driving behavior and adventurous driving behavior,and corresponding vehicle driving rules are formulated for each driving behavior.Under different driving behavior conditions,analyze the conflicts and delays between vehicles turning left and vehicles going straight on the main road at the intersection.Based on cellular automata,a traffic flow model of unsignalized intersection considering the influence of left-turning vehicle turn signals is constructed.In the model,the driving rules of vehicles on the entrance road considering the factors of turning vehicle turn signals are formulated.The impact of traffic flow of the distance between the turn-on position of the left-turning vehicle turn signal and the intersection is analyzed from three aspects:the average driving speed,traffic density and time and space map of traffic at Inlet road.Through simulation analysis,When the left transfer traffic is low,the conservative driving behavior is more conducive to the operation of the traffic flow of the unsignalized intersection;when the left transfer flow is high,the steady driving behavior is more conducive to the operation of the traffic flow of the unsignalized intersection.Before arriving at the unsignalized intersection,Left-turning vehicle open the turn signal in advance to provide information of Lane change,which is conducive to improving the transportation efficiency of Imported road of the intersection;but opening the turn signal Prematurely will cause waste of road resources and reduce the transportation efficiency of adjacent lane and creat a large impact on normal driving of adjacent lane vehicles;It is recommended that the left turn vehicle opens the turn signal when distance between left-turning vehicle and intersection is 70 meters to 80 meters. |
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