Research On The Differential Transit Period Of Railway Freight Based On OD

In recent years,with the improvement of China's railway overall level in equipment and transportion organization,there has been tremendous changes on the conditions of railway transportation.The current calculation method of transit period,which is based on the transport conditions of the 1980s,has been seriously divorced from the production practice.Current calculation method of transit period has the following problems:the delayed delivery and advanced delivery exist simultaneously;Actual delivery time is much less than the calculated transit period.The reason for the former is that the OD transport conditions are different,which causes the coexistence of delayed delivery and advanced delivery.The reason for the latter is that transit time is saved,cargo capacity is gradually released given to the improvement of the overall level in transport conditions.In order to solve the current problems of timeliness and punctuality of transit time,this paper presents the thoughts of differential transit period of railway freight based on OD.Differential transit period of railway freight based on OD is a bold innovation in calculating transit periods of railway freight trasporation,specifically,it is different from the calculation method based on transport distance at present.On one hand,differential transit period of railway freight based on OD saves the transit time.On the other hand,it improves the punctuality of the transit period.The calculation method of transit period based on OD is a new idea for calculation method of transit period.Firstly,this paper analyzes the development and theory status about transit time at home and abroad,in addition,it presents the differential transit period based on OD.Specifically,this paper includs the following parts:analysis of the related issues and theory at home and abroad,introduction of the advanced ideas and methods which can be used for reference,the analysis of the feasibility and characteristic of transit period based on OD,the proposal of the thinking of differential transit period of railway freight based on OD.Secondly,according to the actual production data,the paper analyzes the influence factors impacting timeliness and punctuality and determines the probability distribution of each link time in transit by adopting quantitative and qualitative methods.The specific work includes following parts:investigation and analysis of the current situation of-the punctuality and timeliness of railway goods' transit time,analysis of the main operations which have an impact on the railway goods' transit time by the principal component analysis method,obtain of the distribution law of the operation time in the service process by the statistical method.Thirdly,according to the characteristics of the transit period based on OD,this paper establishes a stochastic longest path and optimistic shortest path model for constrained stochastic network planning and designs the algorithm to solve the model.The special works include the following parts:the introduction of the optimistic value and pessimistic value to deal with constraints of confidence level,the introduction of reserve time to get the planning time-limited windows of transit period,the design of hybrid genetic algorithm based on simulated annealing method to improve the local optimization ability of algorithm.Finally,this paper verifies the model and algorithm with examples.The special works include the following parts:calculating transit period planning time-limited windows of the radial OD network.Analysis of the reliability of transit period based on OD,providing advice for confidence level of planning time-limited windows,providing advice to improve timeliness and punctuality of transit time of freight.