Study On The Characteristics Of Traffic Stream And Capacity At Large Signalized Intersection Under The Condition Of Ice And Snow

With the steady growth of motor vehicle ownership in recent years,people gradually from public transportation to private car travel mode of transport,traffic congestion problems need to be solved.As the node of the city,the intersection has transformed the direction of traffic between different cross,diversion and confluence,and the traffic flow characteristic is complex,traffic congestion is particularly prominent,especially during the rush hour in the morning and evening.In addition,China's northern winter is cold,snow and snow have a long duration.The snow and ice conditions have a great influence on the traffic efficiency,road conditions,vehicle performance and driving behavior will change,leading to increased delay of intersection,traffic capacity is reduced,the existing signal timing is no longer applicable,it is important to study the characteristics of traffic flow under ice and snow conditions,and to optimize the signal control and improve the traffic capacity of the intersection.In this paper,the traffic data of large crossroads are investigated by video and manual survey methods,and establish the linear relationship between traffic volume,intersection speed,saturation flow rate and starting loss time of different snow depth.Based on the influence of snow and ice on the parameters of traffic flow,the signal timing optimization is guided by the theoretical study of the adjustment direction of signal timing parameters.By using the gradient method to optimize the signal timing,the adjustment step and the adjustment direction of the matching parameters are selected.Taking the queuing length of each intersection lane as the control target,the signal timing optimization matrix under ice and snow conditions is established as the intersection Target,and selected the delay and traffic capacity as the optimization index.In order to make the simulation environment close to the actual ice and snow conditions,the software parameters should be re-calibrated,and the simulation of different signal timing schemes can be compared and analyzed by Vissim software.Finally,the traffic capacity of large cross signal intersections is further optimized under ice and snow conditions,puts forward waiting area for through vehicles to be set,and a simulation example is given,the validity of signal timing optimization and setting waiting area for through vehicles is verified.