Research On Wagon Flow Organization For High Value-added Freights In Regions Outside Express Freight Trains

China's Economic "New Normal" and industrial restructuring has stimulated the growth of the demand for high value-added goods.And the organization of railway freight transportation has gradually turned to market demand-oriented.However,the organization structure and development of Express Freight Trains are not adapted to characteristics of high value-added freight,which are widespread,unequal,small batch and diverse.As a result,there is part of goods could not be carried directly by railway express trains and it weakens the competitiveness of the railway in the high value-added freight market.This paper focused on high value-added cargo transportation outside express trains,which has been seldom researched.Trying to enhance and expand the attraction of freight trains except express freight trains for high-value goods.This has practical significance in improving the railway timeliness and satisfying the objective demands of socail transport,railway development as well as environment.Based on the characteristics of high value-added wagon flow and the existing transport organization in China,it optimized the wagon flow organization in regions outside express freight trains and accelerated its speed by combining the method of reserving axle loads in technical through trains and the optimization theory of wagon flow re-sorting.The main research of the dissertation included the following contents.(1)Summarized the meaning and the characteristics of high value-added goods.Based on the historical data of its demand and the forecasted results in 31 provinces or cities in China,the paper concluded that the characteristics of high value-added freight flow were widespread and extremely uneven.Meanwhile,the development of railway high value-added goods transportation and its products at home and abroad were traced back.(2)With special emphasis on the analysis of operation organization of express trains in China,the reasons for the existence of high value-added freight outside express trains were expounded combined with the characteristics of high value-added freight flow.Aiming at transport organization in that area,this paper put forward the further research of using reserving axle loads in technical through trains and wagon flow re-sorting to reduce the traveling time of wagon flow and re-sorting time in marshaling stations.(3)Following the idea of stepwise optimization,the wagon flow organization process could be divided into two phases:axle loads reserving in technical through trains and the optimization of re-sorting wagons.Firstly,rationality and feasibility of reserving axle loads method were discussed.Then,the gains and loss of time value in the process of supplementary axle loads were discussed in detail based on the time-value-saving cost of high value-added freights as well as the loss of capacity by under-loaded operation and extra stopping time caused by technical through trains.Considering wagon flow re-sorting and wagon aggregation of technical through trains,the comprehensive time value cost was also determined.Then a non-linear integer programming model was constructed with the objective of minimizing the comprehensive time value cost.Examples of a single express station example and multiple express stations were designed.In the case of the example of a single express station,the consistency between the solution results of different high-value-added vehicles and the minimum value of wagon flow in the supplementary axle loads process proves the correctness of the model and the program.(4)On the basis of(3),combined with the basic theory of optimizing re-sorting wagons,the problem of re-sorting wagons was transformed into Minimum Cost Flow Problem in traffic service networks and transit time with re-sorting at marshaling stations was regarded as time cost of arcs.The model was developed to the axle loads reserving model based on the optimization of wagon flow re-sorting was constructed.Then the model was solved under the same example of multiple express freight stations using the shortest path algorithm and commercial software.Compared with the typical organization,all schemes of examples with single and multiple express stations reduced the time-value consumption,which verified the rationality of the model and the correctness of the solution methods.In the comparison of schemes before and after model optimization,the time-value savings of schemes between the optimized model and typical organization was increased,which verified the rationality and optimization of the developed model.The dissertation includes 31 figures,16 tables and 71 references.