The Study On Prioritizing Signal Strategies Of Modern Tram

Modern trams are mostly in the form of semi-independent right of way.At the intersections,trams share road rights with social vehicles and are interfered by social vehicles.Therefore,trams should be controlled by traffic signals.Considering design and actual operating experience,the major delay in the main line operation of the trams is due to the influence of intersections in deed.Thus,the application of trams signal priority can reduce the delay and improve traffic capacity,and ensure punctuality and improve the service level of trams.Firstly,this paper elaborates and analyzes the characteristics of modern tram system from five aspects,including vehicle technical characteristics,travel speed,transportation capacity,operation organization of network,environment protection and comfort.After that,considering the characteristics of mixed traffic flow of domestic road traffic,the paper proposes the signal system design principles of trams.Based on the characteristics of the tram system,the four important subsystems of tram signal system are analyzed and discussed(Priority Control Subsystem of Intersection,Control Subsystem of Main Line Turnout,Integrated Scheduling Management Subsystem and Vehicular Subsystem),so as to set up a frame of tram signal system.Combined with the characteristics of tram system and considering its position in urban traffic,this paper puts forward the demand of signal priority control of intersection.It presents as to improve the transportation efficiency of trams at intersection,and keep the road traffic at an acceptable level.On the basis of the design principles of road traffic conventional phases,the paper raises the design principles of trams signal phases relating to signal priority.In addition,analyzing the conflict between tram and traffic flow,the design form of phase and phase sequence,the paper comes up with six design cases of phase sequence.Then the paper makes sure the signal timing principle with tram signal priority,that is,the minimum green time should ensure tram safety clearance.Then this paper uses VISSIM traffic simulation software as a platform,with VAP(vehicle sensing controlling)module,simulating the different passing situations of tram in intersections,and then takes the intersection delay as a evaluation index,obtaining the adaptability of Prioritizing Signal Strategies at different types of intersections.That is,in the intersection of trunk and branch roads,the absolute priority control strategy should be adopted;in the intersection of trunk and secondary roads,the relative priority signal control strategy should be adopted;in the intersection of two trunk roads,there is no need to set signal priority.Finally,this paper combines theories with the concrete application of the Chengdu modern tram line Rong 2,exhibiting the design and technical realization of the signal priority in the intersections.