Research On Integrated Optimization Of Railway Express Freight Train Service Plan And Rolling Stock Circulation

With the adjustment of China's economic structure and the development of the logistics industry,the demand for express freight transportation has become increasingly prominent.The development of railway express freight transportation that adapts to modern logistics is the current trend of railway freight transportation and the future development.The railway express train is an important support for the railway expansion express market.As an important part of its transport operation plan,it is necessary to optimize train service plan and rolling stock circulation plan in an integrated way.On the one hand,it can reduce the empty car kilometers,reduce the operating cost and increase the operating income of railway department;on the other hand,it can guarantee the transportation operation work of the railway express train,which is of great significance.The research contents of this paper can be summarized as follows:First of all,this paper summarizes the present situation of the organization of railway express freight train transportation at home and abroad.By analyzing the development experience of foreign railway express trains and elaborating the characteristics and shortcomings of domestic railway express trains,then puts forward the development direction of China's railway express train in the light of the new situation of the current railway freight market.Secondly,this paper introduces the basic theory of the integrated optimization of railway express freight train service plan and rolling stock circulation in detail.Firstly,the basic contents,influencing factors and optimization ideas of the train service plan and the rolling stock circulation plan are elaborated,and the research boundary of the rolling stock circulation plan is defined.Then,the necessity of their integration optimization is analyzed,the characteristics of the optimization method are also proposed,and the integrated optimization idea is given.Thirdly,an integrated optimization model of train service plan and rolling stock circulation is established.Based on the analysis of the existing modeling ideas,the integration optimization problem is transformed into the dynamic service network design problem considering rolling stock circulation.Then,two construction methods of space-time network are deeply analyzed,and a dynamic service network construction method based on network splitting is proposed to clearly describe the process of freight transportation and rolling stock circulation.Based on this,an integrated optimization 0-1 integer programming network flow model is constructed to maximize the railway operation revenue,taking into account such factors as train Train arrival and departure time,making up content,freight transit,rolling stock connection and carrying capacity.Fourthly,aiming at the difficulty of solving large-scale problems,a decomposition-based Lagrangian relaxation method is designed.The Lagrangian dual problem is constructed by the difficulty constraints in the relaxation problem.The original problem is decomposed into freight flow and vehicle flow that two kinds of independent space-time shortest path sub-problems,so that parallel computation can be used to speed up the solution.Finally,in the case analysis and case validation,CPLEX is used to solve multiple computing scenarios under small-scale virtual railway network.The results show that the integrated optimization method in this paper can not only quantify and analyze the benefits of train operation under differentiated transportation organization,but also optimize and adjust the service plan and rolling stock circulation plan in an integrated way,which verifies the correctness of the model.Under the same data set,the results of comparison between CPLEX and Lagrangian relaxation algorithm show that the algorithm improves the speed of solution while ensuring the quality of solution.Furthermore,the results of calculation based on large-scale railway piggyback transport case show that the algorithm still shows high quality and efficiency when CPLEX can not solve it,which indicates that the optimization method in this paper has certain practicability.