Analysis And Optimization Of Urban Ring Traffic Capacity

Circular overpass has the advantages of small conflict,avoiding the stop signal and traffic safety,and plays an important role in urban roads.In recent years,with the continuous development of economy and the increasing number of urban motor vehicles,the shortcomings of the insufficient capacity of ring flyover have been gradually exposed.Morning and evening rush hour traffic nearly paralyzed,traffic efficiency is getting lower and lower.The domestic practice is usually to directly dismantle the roundabout to replace the cross signal control intersection.There is no scientific and reasonable theoretical analysis before the transformation,and there are many problems in the transformation process.Firstly,this paper summarizes the existing capacity calculation models of ring overpasses in foreign countries,analyzes the capacity calculation methods under different control modes,and derives the capacity calculation methods of ring overpasses under different control modes according to the traffic situation in China and the Angle of convenience for research.Secondly,the phase continuation design,green time and green time interval of signal control loop overpass and signal control intersection are analyzed respectively.Then,the capacity of annular overpass and signal-controlled intersection is compared and analyzed,and the capacity calculation model of annular overpass is optimized to obtain the traffic volume and applicable conditions of different intersections.Finally,combined with the reconstruction example of the ring overpass of Harbin’s three main power lines-haping road,after the comparison of traffic capacity,engineering investment and other factors,the ring overpass without signal control is finally selected to be transformed into a cross control intersection.The feasibility of the engineering scheme is verified by the saturation theory calculation and the VISSIM simulation software for the indexes such as delay and queue length.