Study On Models And Methods For Dynamic Railway Empty Wagon Distribution

The distribution of empty wagon is one of the cardinal elements of railway transportation technical program and the daily adjustment of railway transportation. In America, the percent of empty of total wagon kilometers is up to 45%. In China, there are approximately 500,000 freight wagons, and the average ratio of empty wagon kilometers to loaded car kilometers is about 30%, and the max ratio even perhaps reaches 60%. Obviously, empty wagon distribution plays an important role in the efficiency of railcar utilization, the degree of meeting freight demand, and the modernization of railway operation. It represents technically an optimizing problem of reasonably wagon usage. The research on models and algorithms of empty wagon distribution makes significant sense in both theory and practice.The paper focuses on theoretical research, plentifully uses former results of the references, introduces systematic science, analogy and means of mathematic models, and combines theoretic of correlated knowledge, such as discrete math, optimization and computation to deeply analyze the optimizing problem and to achieve the purpose of providing a new modeling thought and resolving algorithm.The main content and conclusion includes:(1) The resources, adjusting principles and ways of empty wagons are depicted and analyzed in detail.(2) Quantity distribution and network matching flow are found to be the key problems which should be solved by analyzing the features of the empty wagon distribution.(3) In the range of railway administration (or company), empty wagon distribution service time-space network with discrete period is designed. The network has not relation to transportation of empty wagons on the way, but refers to the situation of them in the origin and destination. It is a sort of dynamic processing to the static OD match network, which helps optimize modeling.(4) The minimum cost of empty wagon in distribution is selected as the final target. And the carrying path in the time-space network and the cost in transportation processing of the empty wagons are also discussed. The operating expenses and time delay expenses in empty wagon distribution should be taken as two main expenses which influence problem decision. In order to reduce the complexity of modeling and resolving, the operating expenses and time delay expenses should be converted to a united expenses unit.(5) The problem on designing the empty wagon transport services network is studied which is the foundation of this research. Further more two kinds of model are expressed for the empty wagon flow problem in this paper. The empty wagon flow model is extended to create the empty wagon services network model. And the LINGO is used to achieve integer solution of the dynamic model.I hope that the research work and conclusion of the paper could be hopeful to get further progress for solving the empty wagon distribution problem.