Research Of Traffic Organization At Multi-way Intersection

In recent years,the number of motor vehicles in urban areas is continuously and rapidly increasing.Consequently,a lot of severe "urban diseases" arises,such as Traffic congestion.As urban transportation nodes,the road intersections should take most responsibility for urban traffic congestion,among which the ones consist of five or more roads are often formed huge or abnormal because of social and historical reasons.Many roads intersecting leads to the complicated traffic flow conditions and the huge amount of traffic,which makes the inherent deficiency of multi-road intersections more distinct.Specifically speaking,the unreasonable intersection angles,overlarge areas and unbefitting turning radius severely restricting the efficient operation of multi-road intersections.This paper analyzed the traffic characteristics of multi-lane intersections,which shows more complicated in various aspects such as traffic conflicts and traffic flow characteristics,compared with regular crosses and T-junctions.Aimed on the immediate goal,to reduce the conflicts and to improve operational efficiency,by taking channelization designs as first important measures to improve multi-lane intersections,the detailed analysis of the suitable canalization measures used for multi-lane intersections has been made.And on the basis of canalization design,this paper analyzed the signal control methods applicable for multi-way intersections.Through the conflicts’ condition,the design of the phase structure of signal and the calculation methods of the timing are analyzed.In view of the actual case of the Optics Valley intersection in Wuhan,based on canalization design and signal control methods applicable for multi-road intersections,two types of traffic organization schemes,which are necessary after the demolishing of the main roundabout at the center of the intersection,were proposed.First one is the without-roundabout scheme to ensure the smooth flow of traffic on the main road with large traffic.The other solution has retained the counter-clockwise circling method without signal for some of the inlets.Through traffic simulation,the current situation of the roundabout and two kinds of improvement schemes design are analyzed in-depth.The comparison of these two schemes found that the efficiency of the without-roundabout scheme is far better than the other,according four indexes at the intersection: traffic flow,transit-time,delay time and queue length,while the second scheme showed a significant increase only in traffic flow.Finally,an evaluation index system for multi-lane intersection traffic organization schemes was established.Besides the four indexes that directly reflect the operational efficiency of vehicles,the complexity of intersections,the intersection area and the number of pedestrian crossing facilities were selected as indirect acting factors that impact on the traffic operation.After the weights of each index determined by the analytic hierarchy process,the grey relational degree of each scheme was derived through the grey relevancy theory.Then the sequence of each scheme from good to bad was concluded as without-roundabout scheme,partial circuiting scheme and current roundabout crossing scheme.Thus,the feasibility of the schemes suggested for this case,as well as the applicability of this relative research in traffic organization were clearly verified.