Design And Realization Of Controlling Priority Signal Of Modern Tram At Intersection

Fast increase of the number of motor vehicles in the city has led to heavy traffic pressure,so more and more cities have chosen to build trams as the public transport to improve the situation of urban traffic.The traditional intersection signal made the trams stop and wait at the intersection,resulting in increased delays and reduced operational efficiency of the trams,and the existing tram signal priority system only for a single intersection,which was not taking the signal correlation between multiple intersections along the line into account,and it is difficult to describe the actual traffic conditions.Therefore,a method of signal priority control based on the intersections' signal coordination is designed in this paper,which could realize priority signal of the tram at the intersection and bring out a smaller impact on the social vehicle.The positioning technology,embedded technology and wireless communication technology is applied in this paper to designs an intersection signal priority controller for tram,and this design achieves the priority of the tram at the intersection,and it includes the signal coordination priority module,data storage module,wireless network communication module,controller and intersection host computer.The delay of the vehicles at intersection based on the traditional Webster signal timing is analyzed by the signal coordination priority algorithm,and the delay function is optimized by using the particle swarm optimization algorithm with the minimum delay as the target and the phase difference of the intersection signal as parameters to achieve multi-junction signal coordination control,and calculates the time to reach the intersection by using the trams' location message,combinates the methods that sharing time,extending green time and shorting red light time to provide priority traffic signal for the tram at the intersection.The data storage module uses the SPI port to operate the FLASH module through the MCU to store and read the prepared data sent by the monitoring center.Wireless LAN communication module uses the serial port to operate the wireless module through the MCU,connects the AP to achieve communicate with the monitoring center,tram and other equipment,accessing to preparation time of the tram,train speed,location and other information.The MCU takes the CORTEX-M3 architecture ARM chip as the processor,to receive the information and management form the tram and management side through the wireless network communication and make corresponding responses,and controls signal according to the current traffic condition of intersection,the prepared data and the program of coordination priority signal.Host computer applies MFC to realize social traffic simulation of the intersection and priority signal monitoring,bringing convenience for the debugging.Through the system test,the intersection can provide real time priority signals for the tram,achieving the desired effect that the trams enjoy the right of priority access at the intersection.The experiment results show that this system is with the advantages that high real-time,high reliability and scalability,etc.it can reduce the delay of social vehicles along and achieve the trams' signal priority,and plays a positive role in improving the operating efficiency of trams.The system could reduce unnecessary parking waiting time of the tram at the intersection,and has a certain practical significance.