Research On Robust Optimization Of Operation Schedule Of Overlapping Bus Routes

Reasonable bus schedule design is conducive to improving the service level of urban public transport.With the rapid development of urban public transport,it is inevitable that overlapping routes will appear.With the increase of passenger travel choices,the scheduling difficulty will also increase.Most of the existing timetables are formulated under deterministic conditions,but in the actual bus operation process,there are various challenges.Random factors make the bus punctuality rate low.In order to solve the above problems,based on the two situations of system optimization and line coordination,this paper takes three overlapping lines in Harbin as a case to study the robust optimization model of the overlapping line schedule.Firstly,starting from the definition of overlapping lines,analyze its line characteristics and passenger flow characteristics;expound the definition and influencing factors of overlapping lines bus scheduling,and subdivide them into system optimization and line coordination according to the difference of collaborative optimization goals.Overlapping route bus scheduling;a scenario-based discrete robust optimization decision-making framework is given,and the characteristics of four typical discrete robust optimization models are analyzed and summarized.Then,the passenger travel strategy is analyzed,the space-time network is introduced to describe the passenger travel selection p rocess of overlapping lines,and the passenger flow allocation method of the space-time network under the capacity limitation is proposed to simplify the calculation of passenger travel time;based on the robust decision-making framework of discrete scenarios,the passenger travel cost and public transportation are comprehensively considered.Operating cost,taking the departure interval of vehicles on each line as the decision variable,weighing the expected value of cost and the expected value of cost deviation to establish a robust model for the optimization of overlapping line schedules;and using the idea of traversal to design related algorithms to solve the model;through case analysis,the results show that : The spatiotemporal network can effectivel y simplify the model calculation process,and can intuitively display the passenger loading situation of vehicles on each line;the robust optimization model of overlapping line schedules can effectively avoid the risks brought by uncertainty on the basis of ensuring better cost.Finally,the characteristics of three bus coordination strategies including uniform departure strategy,flexible departure strategy and flexible departure strategy are analyzed,and the line coordination effect and the calculation efficiency of the combined optimization model are compared.The maximum number of simultaneous transfers is the optimization goal,and the departure time of each train on each line is the decision variable to build a robust optimization model for overlapping lines under line coordination;the model is linearized so that commercial solvers can be used to solve small-scale problems,while designing Genetic algorithms are used to solve large-scale problems.Through case analysis,the results show that the flex ible interval departure strategy can effectively improve the transfer efficiency;with the increase of the weight coefficient,the expected value of the weighted synchronous transfer times shows an increasing trend,and the growth rate slows down when it i s greater than 0.4;with the increase of the number of scenes,the expected value of the weighted synchronous transfer times gradually becomes smaller,and the decrease becomes smaller when the number of scenes is greater than 30.The results of the paper can provide decision support for managers to implement the refined operation management of overlapping lines,improve the reliability and scientificity of bus schedules,and then enhance the attractiveness of public transport.