Study On The Optimization Of Wagon Flow Organization In The Loading Area Of Heavy Haul Railway

Heavy haul railway has become the main transportation channel in China for its large capacity, low cost and high efficiency. However, with the development of the industry in China, the heavy haul railway cannot meet the increasing demand on resources since its transport capacity limit. So improving the transport capacity is necessary and urgent. So far, there are three main ways to improve it, which are improving the weight of the train, increasing the intensity of the trains and ascending the speed of the wagon. But there is a little room for improvement for these three measures. Optimizing the wagon flow organizations is a method to improve the transport capacity from another perspective, which modifies the organization schemes, the routine selection and the volume of each wagon flow organizations to allocate the resources of the railway network. In 2008, Daqin railway firstly put forward the idea of optimizing management about integrating collecting and dispatching which increased the transport capacity of Daqin railway largely. So it’s necessary to make a general optimizing strategy for the wagon flows, aiming to improve the performance of the economy of the heavy haul railway in China.In order to make a full use of the exist capacity of the heavy haul railway and to ensure the transportation resource balance, the volumes of wagon flow and organization schemes of each line in the heavy haul railway network must be reasonably planed. The optimized strategy of the railway network must ensure that the optimization of wagon flow organization can be used to improve capacity, but also to overcome all the bottlenecks of the existing road network. In addition, it needs to find the best breakthrough for improving the capacity of the heavy-haul railway in the future.(1) This thesis firstly analyzes the characteristics of the heavy haul railway in China. And then the improved Grey Relational Analysis is used to find the most critical factors affecting the circular speed of heavy haul train by studying the relational order of the different influencing factors, and then the theory and method of determining the transport organizations related to the accelerated cycle speed is used.(2) The characteristics of different types of wagon flow organization and its influence on the cycle speed of train are analyzed, and then the advantages and conditions of direct wagon flow in the loading area are studied. Based on the analysis of the direct wagon flow, this thesis builds a multi-objective optimization of the wagon flow organization for heavy-haul railway (MWFHR). The model aims to maximize circular speed and to minimize circulation time and logistics cost while satisfying the constraints on the total demand for commodities, yard capacity, and routing capacity.(3) Since the parameters and the constraints of the MWFHR are complicated, this study proposes a bi-level algorithm to solve the MWFHR. In the lower level, the ant colony optimization (ACO) algorithm is used to collect wagon flows for the organization. This level also sorts the organizations according to the sum of the time and the logistics costs. In the upper level the traversal search algorithm (TSA) is used to screen the optimal solution set that can minimize total cost under various constraints.(4) Based on the study of the former researchers, this thesis proposes an optimization organization of loaded empty wagon flow formation plan (LEWFP) for empty wagon flow. This model aims to minimize the travel distance and the total time of the operation while satisfying the quality demand of different empty wagon styles. And the bi-level algorithm is also used to solve this model.(5) One loading area of A heavy haul railway network is taken as an example to verify the validity of the two models. The results show that the models can promote the allocation of the organizations of wagon flows and decrease the transportation cost.The two models proposed in this thesis are general models which are under the premise of the total demand for commodities and the other bottlenecks, making a full use of the available resources to improve the capacity, decent the transportation cost and maximize circular speed of the wagon flow, which provides a reference and basis for allocating the wagon flows of heavy haul railway in China.