Model And Algorithm For Train-to-Yard Assignment At Bidirectional Marshalling Station

In this paper,the optimization problem of train-yard assignment in railway bidirectional marshalling station is studied.The arrival trains and their marshalling contents in a given planning period,the marshalling requirements of the planned departure trains,and the arrival and disassembly capabilities of the uplink and downlink systems of the bidirectional marshalling station are given.The problem is to determine the access and dispatch system of the arrival and departure trains,so that each departure train meets the full axis,punctuality and non-violation requirements,the capacity of each system does not exceed the limit,and the total residence time of the cars at the station is minimal.This paper first discusses the main work content of the bidirectional marshalling station and the matching equipment and working strategy based on the field practice.Combined with the characteristics of dispatching control of bidirectional marshalling station,this paper expounds the technical operation process of train flow in bidirectional marshalling station and the principle followed,clarifies the operation mode of technical process of train arrival,disintegration,aggregation,marshalling and departure,and establishes the corresponding relationship model.Then,this paper defines the train-to-yard assignment problem(TYAP)of bidirectional marshalling station and establishes the basic theory of the train-to-yard assignment optimization of bidirectional marshalling station.According to the basic theory of bidirectional marshalling station train-yard assignment optimization,this paper aims at minimizing the total time of vehicles staying at the station.Firstly,the bidirectional marshalling station train-to-yard assignment problem is constructed as an integer nonlinear programming model.Then,according to the characteristics and relationships of decision variables,it is further transformed into an integer linear programming model by mathematical methods.This model takes into account the requirements of train flow connection,departure train marshalling regulations and system arrival-departure capacity.In addition,according to the characteristics of the problem,the genetic algorithm(GA)for the train-to-yard assignment problem of the bidirectional marshalling station is designed.The 0-1 encoding is used to represent the arrival train receiving system.In the decoding,the remaining departure train dispatching system and its marshalling content decision are solved by designing a heuristic algorithm.The fitness function based on nonlinear ranking is used to evaluate individuals,and the single-point crossover operator and single-point mutation operator are used for population evolution,and the punishment strategy is designed to deal with the infeasible individuals that may be generated in the evolution process that violate the limitation of system receiving / dispatching ability.Finally,taking Zhengzhou North Railway Station as the background,a practical example with different planning period length / different scale is designed to carry out the calculation and analysis.The LTYAP model,GA algorithm and two heuristic rules simulating field experience are compared and analyzed for a small example with a planning period of 4 hours.The influence of system adaptation capability parameters on the quality and efficiency of the proposed method is discussed.A total of 20 examples of different scales are constructed by extending the planning period and adjusting the system capacity parameters to further test the solving performance of LTYAP model,GA algorithm and two empirical rules.