Research On Comprehensive Optimization For Arrival-departure Yard Tracks Utilization In Railway District Sastion

As the basic unit of railway transportation production,district stations are called "small and complete" stations,which collect a large number of equipment,receive and deliver all kinds of trains and process corresponding technical operation.District stations play an important role in passenger and freight transportation.In this paper,the influence of the locomotive route on the utilization of arrival-departure tracks is considered,and the optimization problem of the comprehensive utilization of arrival and departure yard tracks is studied.The main contents are as follows:(1)Based on the analysis of the process and content of train technical operation at station,the time and space continuity relationship between various train operations is described.Then,on the basis of the method of building station topology map,the route of each operation is searched.(2)A mixed integer linear programming model is seted under different releasing conditions.The model uses cumulative flow variables to describe the real process of route releasing under different releasing conditions.On the basis of cumulative flow variables,we describes the receiving and departing operation,the entrying and exiting locomotive depot operation,and the transit operation in a system.The conflict between the same train operation and shunting operation,the conflict between different train operation and shunting operation,and the conflict between different train shunting operation and shunting operation are described more microcosmically and meticulously as the conflict between different train operation occupying station resources.(3)A decomposition iteration algorithm based on Lagrange relaxation is designed.Based on the characteristics of cumulative flow variable model,the algorithm divides the constraints of the model into two categories: one describes the operation process of a single train at the station and the other describes the conflict relationship between the trains occupying the station resources;on this basis,the relaxation dual problem of the comprehensive utilization optimization problem of arrival-departure yard tracks is established by using Lagrange multipliers;and the original problem and relaxation dual problem are decomposed into several subproblems of a single train operating on the station.To solve the subproblem,a time and space shortest path algorithm based on dynamic programming is designed,and the solution of the relaxed dual problem is taken as the lower bound of the original problem.The feasible solution of the original problem obtained by heuristic rules is taken as the upper bound.The Lagrange multiplier is adjusted by sub-gradient method and iterated several times to update the original problem.Finally,a satisfactory solution is obtained from the upper bounds of the problem.(4)A typical section station layout chart is used to set up an example.The receiving and dispatching operation of 40 trains with 4 hours under different releasing conditions and the corresponding shunting operation assignment route and route occupancy time are designed.The influence of different releasing conditions on arrival and departure capacity is obtained by comparing the total deviation of train arrival and departure time.