Railway Transportation Organization Model And Method For Accelerating Railcar Cycling

As the key factor of implementing railway connotation extended reproduction, reducing railcars cycle time(RCT) can effectively expand the transportation capacity and alleviate the bottleneck restriction of railway transportation. Statistics show that, in China, cutting down the average cycle time of railcars for one hour there will be billions of money saved. As the RCT problem involves almost every aspect of railway operation, models and methods of reducing RCT need to be studied futher in theory and practice systematically.It is obvious that reducing RCT can make significant sense. However, systematically studying the theory and feasible methods of reducing RCT is still rare in home and abroad. This study tries to study the optimizing models and methods of cutting down RCT from the aspect of car flow organization, equipment and facility configuration, vehicle management, stations operating plan, and trains schedule.Generally, when a railcar finishing one round of turnover, it will have to spend time on loading and unloading process, main line transport, and yard transfer. These three parts of time delay compose the whole cycle time. Based on deep analyzing the forming and changing mechanism of RCT, the study focuses on: Analyzing the impact of providing more direct freight trains on loading time and transfer delay at yards; Dealing with optimization of the empty car distribution aiming at reducing empty car travel distance, and the routing problem of loaded freight cars for the sake of shortening travel distance; Investigating the impact of cutting down railcar transfer times and extending blocking distance on car cycle time; Developing optimal picking-up and delivery model at loading station.In this study, methods and techniques of comparative analysis combined with mathematic programming are used to quantitatively study the forming mechanism and main influential factors of RCT. Integer 0-1 programming and network flow techniques are also used to develop train routing and car transfer models.The main innovations of the study include:1. From the microcosmic point of vehicle management, this dissertation studies empty car distribution and railcars routing problem. According to the characteristic of china railway transportation capacity restriction, multi-commodity and multiple car types of loaded and empty railcar flow routing and distribution model is proposed. Based on northeast China railway network, distribution plan of 975 demands is taken as an example to demonstrate the validity and rationality of the proposed model. Computational results show that the model can generates high quality plans of car routing and distribution.2. This study describes and analyzes the current empty car distribution process, identifies the shortcomings, and stresses the importance of reliable distribution process for satisfying customers' demand and reducing car cycle time. An integer programming model for distribution of empty cars with considering cost of car type substitution is formulated. Based on the demands of 18 China railway bureaus, the distribution plan generated by the model can satisfy clients' demands for empty cars by finding alternative types and origins of cars. Computational experiments with the model indicate that the model generates distribution plans that can improve the quality of the distribution process.3. On the basis of detailed analysis of the cost of car flow in the process of loading and unloading, car movement, and the cost of car inventory at clients warehouse, a mathematical model, which determines optimal direct train connections for all O-D demands in loading area by minimizing the total cost of logistics system, was formulated as a nonlinear 0-1 programming problem. The proposed model can comprehensively describe the blocking strategy and various combinations of O-D demands in loading area. It is very important for the railroad to consider clients inventory cost because the loaded cars have to wait for unloading if more direct trains arrive at the destination in a short time interval. This will inevitably prolong cars cycle time.4. The study deeply analyzes the impact of station operating plan on railcars loading and unloading time, and developes a railcar picking-up and delivery optimizing model aiming at minimizing railcar loading time cost and locomotive transport cost. The proposed model considers more than one locomotive and railcar loading site, and it also overcomes the shortcomings of current optimizing methods that only consider the cost of locomotives in loading stations. This model can effectively improve the efficiency of locomotive operation and shorten the picking-up and delivery time of railcars.5. Finally, in the background of current China railway reforming and adjustment, it also studies the impact of providing more direct trains on reducing cars blocking time, extending transfer distance, and thus cutting down cars transfer delay time in case of implementing extended locomotive routing and trains checking distance, and unifying trains hauling weight in main lines and sidings.In literature, this study first systematically researches models and methods for RCT problem in circumstances of current China railway network, car flow structure, and moveable equipment and facility. The completion of this study is useful for establishing theoretical foundation of obtaining feasible strategy, and providing short-term effective measures and long-term industrial policy of reducing RCT for decision makers.