Simulation-Optimization Of Railcar-Flow Allocation Problem In Railway Unidirectional Marshalling Yard

Marshalling yard is an important core of railway freight network which undertakes the rearrangement and transfer operations of a large number of trains.The one-way marshalling yard,as a common type of yard at home and abroad,has complicated operations due to its concentrated operations and the interference of a large number of reverse rearrangement railcars-flow,which brings the challenge of the yard’s scheduling and operation planning.The decision making of marshalling yards stage plan is a key problem of the yard’s operations management,and the railcar-flow allocation problem is the heart of the stage plan for the one-way marshalling yards which mainly handle the disassembly and assembly operations.A high-quality railcar-flow allocation scheme is of great significance to improve the efficiency of the marshalling yard’s operations and speed up the transfer of the whole railcar-flow in the railway network.The railcar-flow allocation problem is closely related to the calculation of railcars-flow,the shunting locomotives usage and the application of arrival and departure tracks in stage plan,and there are many influencing factors to be considered.On the basis of summarizing the shortcomings of railcar-flow allocation optimization methods in the relevant research at home and abroad,such as high complexity of solution and low adaptability of solution,this paper puts forward a simulation optimization method combining a hybrid integer mathematical model and a simulation model for the railcar-flow allocation problem of the one-way railway marshalling yard.The aim is to solve the solution of railcar-flow allocation scheme in high efficiency,and to comprehensively consider the operational influencing factors,and complete the simulation verification work,which will improve the application value of the solution for railcar-flow allocation and the compilation level of marshalling yard stage plan.Firstly,the relevant theories of railcar-flow allocation are expounded.It includes the main technical operation processes in the railway one-way marshalling yard,the concept and characteristics of the problem,etc.And the coupling relationships between the railcar-flow allocation problem and the stage plan is analyzed to illustrate the optimization necessity of this problem.Then,an optimization model of railcar-flow allocation is constructed based on the analysis of the mechanism of railcar-flow allocation problems,which aims at minimizing the waitting time of all the adapted railcars in the yard.It provides a scientific guidance model for solving the railcar-flow allocation problem.After then,a simulation optimization framework for one-way marshalling yard flow allocation problem is proposed to solve the comprehensive optimization problem.Including the establishment of technical operation simulation model of one-way railway marshalling yard,which can comprehensively consider the influence factors of shunting operation,shunting tracks usage and other factors and simulate the uncertain operation situation on site,and be used for high-precision simulation verification of the solution.In order to realize the effective combination of optimization model and simulation model,an improved tabu search algorithm is designed,which can cooperate with the optimization model to solve the railcar-flow allocation scheme,and complete the simulation verification and feedback of the solution through the interactive interface.Finally,the Liupanshui South marshalling station in Guizhou,China,is taken as the research object,the effectiveness of the method,the optimization performance of uncertain parameters and the efficiency of the algorithm are analyzed experimentally,which proves that the simulation optimization method has good performance in terms of solution quality and stability.