Research On Optimization Of Car Flow Assignment Based On The Coordination Of Station And Line Capacity In Railway Freight Corridor

It is one of the core problems in the field of railway transportation to scientifically plan the railway freight transportation routes and rationally optimize the car flow assignment in railway transportation corridors.In view of the tight supply of railway transportation capacity and the imbalanced utilization of railway stations and lines in China under the current situation of the national "incremental freight increase" action,from the perspective of capacity coordination of railway station and line,through the introduction of big data sets of railway daily production,combined with the basic theory and method of car flow assignment in railway network,the optimization of the car flow assignment of railway freight corridors is studied in this paper for the purpose of alleviating the bottleneck and capacity waste in railway network and promoting the coordinated utilization of railway network station and line capabilities.The main work carried out in this article is as follows.(1)The basic theoretical framework of railway freight car flow assignment is analyzed.Firstly,the basic aspects of the definition,influencing factors and optimization method of railway freight car flow assignment are analyzed.Secondly,the meaning and standards of the capacity coordination of railway station and lines are further analyzed.Finally,the method and value of introducing large data set of actual trajectory of freight cars are explained.(2)The introduced large data set of actual trajectory of freight cars are used to initially extract the actual car flow paths through the big data analysis technology,then the railway network and car flow are merged from the perspective of the research on the car flow assignment of railway corridors.Finally the alternative sets of car flow paths that are close to actual production combining mathematical optimization models are generated.(3)Based on the traditional car flow assignment model,the railway network node capacity coordination index and line capacity coordination index are proposed,the arc-road model point attribute parameters are introduced,and an optimized model of railway freight corridor car flow assignent with the goals of minimum car flow time and capacity coordination of railway station and line is constructed,which is linearizated by introducing auxiliary decision variables.The model is solved by Gurobi solver,and a small-scale calculation example is designed to verify and analyze the validity of the model.(4)In connection with the large-scale road network optimization problem,a model solution framework including Lagrange relaxation algorithm for solving lower bound solutions and heuristic algorithm for lower bound solution feasibility is constructed in this paper.Firstly,a car flow adjustment ranking index that considers the size and the transportation time of the car flow is proposed,then an overall search idea of the car flow adjustment strategy is proposed,filally,a heuristic algorithm based on the global search for the feasible downward solution is designed so as to improve the solving algorithm based on Lagrange relaxation principle.(5)Case study.A regional railaway network in China is taken as an example for analysis and it is divided into two optimizations whether to consider the coordination of road network station and line capabilities.The results of the two optimizations are analyzed from the aspects of railway network car flow assignment,point and line capacity utilization and parallel channel division of labor,which can ascertain the current status of capacity utilization in the railway network,analyze the bottleneck and capacity waste situation of the railway network,and give suggestions on car flow adjustment and capacity expansion on the one hand and verifies the effectiveness of the proposed model and algorithm on the other hand.By taking into account the coordination of car flow transportation costs and the coordination of railway station and line capabilities,the capacity using balance of the railway network is greatly enhanced,which effectively resolves conflicts and eliminates bottlenecks,so as to cut the peaks and fill the valley of the railway network,and then activate the entire railway network.