Research On The Number Of Railway Freight Trains Considering Different Assembly Modes And Connection Times

With the continuous development of our country’s railway transportation,the cargo transportation capacity has been gradually released,and the railway has gradually changed from a planned type to a market-oriented type.At the same time,the competition in our country’s transportation market has become increasingly fierce,and the competition of different transportation methods has gradually changed from cost competition to the competition of comprehensive service level,this puts forward higher requirements for railway transportation in terms of efficiency and accuracy.For a long time,due to reasons such as transportation capacity and management system,railways need to wait for the trains to be fully assembled before they are allowed to depart,which greatly reduces the timeliness of cargo transportation.In the new era of transportation market demand,the conservative transportation concept of railway can no longer compete with the development speed of modern logistics,so the research on the optimization of the number of trains has become a new breakthrough.The research on the optimization of the number of trains is aimed at maximizing the economic benefits of transportation enterprises.The method of under-axle departure is adopted within a certain range to flexibly determine the number of trains.The optimal minimum number is selected by measuring the running cost of the train.The number of trains,when the trains are assembled to the minimum lower limit,it is allowed to organize the trains,which breaks the rigid condition of full-axle trains.It plays an important role in ensuring the time limit for the delivery of goods,improving the turnover efficiency of trucks,and enhancing the competitiveness of the railway freight market.This paper takes the optimization problem of the number of railway freight trains considering different assembly modes and connection times as the object.The main research contents include:(1)The basic concept of the number of trains is sorted out,and the relationship between the number of trains full axle,the maximum number of trains,the minimum number of trains,and the number of fluctuating trains is analyzed.At the same time,the factors affecting the number of trains are discussed.In addition,make a comparative description of the fixed-point assembly mode and the basic assembly mode and some new assembly modes derived from the fixed assembly mode,and discuss the applicability of the assembly operation mode under the basic operating conditions of the technical station.It provides theoretical support for the fixedpoint assembly mode under the conditions of relaxation of the optimization and selection of the number of trains in the subsequent content.(2)Establishment of the fluctuation model of the number of freight trains compiled based on the connection time.Based on the analysis of the impact of the fluctuating number of trains on the operation system of the technical station,the train departure conditions and the distribution plan of the technical station are optimized.The connection relationship between the departure times is determined,and the fluctuation model of the number of freight trains based on the connection time is established.The optimization scheme of freight train distribution under the condition of fluctuation of the number of trains is obtained through the analysis of an example,and the influence of the maximum and minimum number of trains and the fluctuation rate of the operation time of the technical station on the number of dispatched freight trains and the income of freight transportation is analyzed.(3)Establishment of an optimization model for the number of freight trains in multitechnical stations.Through the expansion of the above model,multiple technical stations are included in the model consideration,and multiple departure technical stations and multiple arriving technical stations are added,and an optimization model for the number of multitechnical station freight trains is established.At the same time,the follow-up traffic flow at the technical station and the delivery of various goods are also considered.On this basis,the number of trains is optimized for the calculation example,so as to determine the freight train distribution plan between technical stations,and the influence of the maximum and minimum number of trains to the station on the income of cargo transportation and the delivery rate of goods is analyzed.(4)The establishment of the operation model of the optimal minimum number of trains under the constraint of the technical station time window.Introduce the concept of operation time window of technical station to determine the influence of the open degree of operation time of technical station on the number of trains,increase the time window constraint of technical station,and focus on the optimal minimum number of vehicles,based on this,the model scenario simulation simulation was carried out,and the relationship between the transportation cost difference,the optimal minimum number of vehicles,and the proportion of invalid time windows in the fixed-build assembly mode and the fixed-point assembly mode under relaxed conditions was compared and analyzed.The influence of the interval distance between stations and the length of time window on the optimal minimum number of vehicles is analyzed.