Study And Implement Of Optimum Route Algorithm Based On Public Traffic Network Model

Urban public transportation is an important part of the whole urban transportation system,its development level is not only a significant symbol of the urban modernization,but also an optimal approach of solving urban crowded traffic problem.The public traffic network model and the algorithm of its optimum route choice is an important subsystem of urban transportation system and the guarantee of the city transport priority,which is significant for the perfection of the city structure and rationalization of land use.This paper firstly summarizes the researches and practices on the public traffic network model and the algorithm of its optimum route choice of foreign and urban cities, analyses the meanings of it and the realization conditions and influence factors for effective running.And then it introduces the chart storage expression of the public traffic network,which is abstracted to a network with the topology property on the basis of analyzing the model.Afterwards,it brings forward that the accessibility of the urban public traffic network can be evaluated by average transfer times(ATT),and presents two algorithms:one is based on the Nth transfer matrix,the other is based on A* algorithm.According to the fact that passengers would like to walk to reduce transfer times usually within their walking distance,a new algorithm is presented to calculate ATT. An example is given to validate the feasibility of it.On the problem of the optimum path choice of the public traffic network,this paper presents two algorithms:one is the shortest path choice algorithm on the basis of network transformations,after network transformations, the public traffic network is transformed into a network without transfer,this algorithm can avoid calculating through matrix and least transfer matrix;The other is the public traffic route choice model based on N shortest paths algorithm which uses the least transfer times as first object and shortest path distance as second object.Considering passengers would like to walk to reduce transfer times usually within their walking distance, a new shortest path algorithm is presented.This paper designs and realizes the urban public traffic query system of Changchun,which is based on the spatial data of Changchun provided by Changsha Pilot Electronic Technology Company.The central function is the optimum path choice of the public traffic network,users can input jumping-off point and terminal on the keyboard or dot on the map, then they can hunt out choices of using the least transfer times as first object and shortest path distance as second object.In addition,there is information query which includes bus stations,bus routes,placenames and public places,it also includes precise and blurry query.At last, this paper summarizes the main points, and brings forward some advice and prospect for the further studies.