Research On Dynamic Distribution Optimization Of Marshalling Station Based On Cargo Priority

With the rapid development of the transport market,customers’ choice of transport mode has become more diversified.Compared with the previous consideration of transport safety,economy and other basic characteristics,customers at present tend to pay more attention to meeting the timeliness requirements of cargo transport.Therefore,in order to adapt to market economy,improve transportation efficiency and shorten transportation consumption time,it is an inevitable trend of railway development to introduce customer transportation timeliness requirements into railway traffic flow organization.As an important technical station in transit,marshalling station is known as "train processing plant".The transfer time of vehicles in marshalling station accounts for about 1/3of the total turnover time.Therefore,in order to meet customers’ requirements for timeliness and improve transportation efficiency,it is necessary to conduct optimization research on transportation organization of technical stations,especially marshalling stations.As the core content of the stage planning of marshalling station,the quality of flow allocation directly affects the whole process of cargo transportation.Flow allocation not only determines the content of the departing trains,but also determines the source of their traffic flow.Therefore,according to the characteristics of railway freight system,this paper puts forward the concept of cargo priority,takes the marshal-yard allocation as the research object,and satisfies the customer’s requirement of timeliness of cargo transportation as the research objective.Through the analysis of various influencing factors of priority,this paper puts forward the comprehensive evaluation method of cargo grade,carries out dynamic classification of arriving vehicles,and takes it into the objective function as an important parameter.A dynamic flow allocation optimization model based on cargo priority was established,and ant colony algorithm was designed according to the characteristics of the model.Finally,the unmarshalling scheme and flow allocation scheme of trains are calculated.The calculation results show that the model and algorithm in this paper can effectively solve the dynamic flow allocation problem of marshalling station,and verify the effectiveness and feasibility of the model and algorithm.The main research content of this paper includes the following aspects:Delivery Time:This paper firstly analyzes the railway freight transportation process,then further studies the components and calculation methods of the delivery time limit,and finally studies the distribution of the delivery time limit in the transportation process,and establishes the probability distribution model of the delivery time limit.Make the delivery time accurately and reasonably allocated to each link involved in the transportation process(mainly refers to the line interval,station,etc.),to provide support for the following research;Classification Of Vehicles:This paper analyzes and studies the background of railway freight transportation organization at the present stage,proposes the concept of cargo priority and introduces it into the traffic flow organization of marshalling station,and then analyzes and studies the four main factors affecting the priority of goods(distribution of delivery time,the degree of traffic delay,the type of goods and the level of customers)respectively.Based on this,a fuzzy comprehensive evaluation model based on combination weighting method is constructed to classify the arriving vehicles.Priority is given to the traffic flow with a higher level,while the other traffic flow with a lower level needs to wait a little,so as to ensure the optimal overall operation of the marshalling station.Flow Distribution:In order to prioritize the traffic flow with high grade and take into account the customers’ requirements on the timeliness of cargo transportation,this paper uses the concept of "cost" for reference,takes the grade of the total score of priority evaluation as the reasonable degree of traffic allocation into the objective function,and takes the minimum sum of the weighted value of the vehicle stay at the station as the optimization objective to construct the objective function,and this weight is the priority evaluation level.Considering the constraints of train flow quantity constraint,marshalling direction constraint,train flow connection time constraint,maximum stay time constraint,marshalling weight or length change constraint,the dynamic allocation optimization model of marshalling station was established,and an improved ant colony algorithm is designed to solve the model by analyzing the model.Finally,the feasibility of the model and algorithm is verified by an example.