Research On Optimization Of Car Flow Assignment Considering Transportation Time And Resorting Cost In Railway Network

It is urgent and necessary to optimize and analyze the car flow assignment in railway network in order to give full play to the freight transportation capacity.The influences of transportation time and resorting operation cost on car flow assignment scheme are considered in this paper,and the comparative analysis of the optimization schemes with or without consideration of resorting operation cost are focused on,and then the importance of resorting operation cost in the process of car flow assignment is explained,which provides decision-making basis for the formulation of relevant plan scheme of railway freight transport organization in China.In addition,with the help of big data analysis technology,the railway daily data is processed first and then fused with the mathematical optimization model,so as to effectively reduce the barrier of the car flow assignment scheme into actual productivity.The main contents of this paper include the following aspects:(1)The theory and method of car flow assignment optimization in railway network are studied.Firstly,the concepts and research scope of car flow assignment in railway freight transportation network are defined.The basic principle of car flow assignment is analyzed,and the influence of time factor and cost factor on car flow assignment is emphasized.At the same time,in order to ensure the validity and feasibility of the optimization scheme,the big data analysis technology is introduced into the study of car flow assignment optimization in the railway network,and the theory of data analysis of car flow assignment in the railway network is put forward,which is "first processing,next application",and the research method of car flow assignment optimization based on the actual routing data of the railway freight car and the statistical data of shunting operation at marshalling stations is given concretely.In this way,the theoretical basis of this study is laid.(2)The optimization of car flow assignment in railway network with the least transportation time is studied,that is,the cost of resorting operation is not considered.This paper puts forward the idea of integrating the results of "first processing" with the mathematical optimization model of basic Arc-Route.Specifically,taking the minimum total transportation time as the objective function,an optimization model of car flow assignment is constructed.A design example is given,the effectiveness of the model and algorithm is verified by comparing the results of optimization with those of K-shortest routings optimization.(3)On the basis of the research content(2),the calculation method of resorting cost of marshalling station considering shunting line operation is further studied.Taking the marshalling station as the research unit,based on the given car flow assignment scheme,and taking the optimization of the shunting line as the grasp,the minimum resorting cost is determined.Specifically,the resorting cost is mainly related to the volume of shunting trips.By analyzing the shunting operation flow of marshalling station,the calculation rules of shunting trips are summarized,and then the method of estimating shunting operation volume of marshalling station is put forward by using big data analysis technology.In the service network consisting of marshalling stations and fulcrum stations,a mathematical model for calculating the resorting cost of marshalling station considering the optimization of shunting line operation is constructed with the objective functions of minimizing the total transportation cost and the resorting operation volume.Taking the optimization results of the research content(2)as an example,the effectiveness of the mathematical model and the algorithm is verified by comparing the index items before and after optimization.(4)The optimization of car flow assignment in railway network with the least transportation time and resorting operation cost is studied.Using the idea of multi-commodity network flow optimization and the estimate method of resorting cost for reference,aiming at minimizing transportation time and resorting operation cost,a car flow assignment optimization mathematical model is constructed,and an improved Lagrangean Decomposition algorithm(ILDA)with parallel adjustment and algorithm acceleration is designed to solve the problem.Finally,using the example of the research contents(2)and(3),the differences of car flow assignment schemes under the condition of considering or not the resorting cost are compared and analyzed from the aspects of line capacity utilization,resorting capacity utilization,shunting operation volume,transportation time and resorting cost.It is found that the car flow assignment scheme considering the resorting cost is not only helpful to reduce freight charges,but also make the utilization of transportation capacity of railway network more reasonable.In this way,the importance of the resorting cost factors to the optimization of car flow assignment is further illustrated.In addition,the sensitivity analysis of the ILDA algorithm is further carried out to verify the effectiveness of the model and algorithm.(5)An actual regional railway network in China is studied.The three schemes of considering or not the resorting cost and actual situation are compared and analyzed in terms of utilization ratio of line transport capacity,utilization ratio of marshalling station resorting capacity,shunting line usage and shunting operation volume.First,the utilization of the capacity of the regional railway network is found out.Next,the bottlenecks of the capacity in the case network are analyzed and the corresponding suggestions for capacity expansion are given as well.In the end,the differences under the condition of considering or not the resorting cost are compared in order to provide decision-making basis and theoretical reference for the relevant railway transport departments.