Research On Robustness Of Train Timetable Based On Buffer Time

The train timetable is the core content of railway transportation organization and one of the most important components in railway transportation organization.It plays a decisive role in optimizing passenger transportation service level and improving railway transportation service quality.One of the main methods to improve the punctuality and reliability of the train drawing stage is to improve the robustness of the train drawing.In order to enhance the robustness of the train timetable,the researchers involved in the preparation of the train timetable will set a certain buffer time in the operation diagram,and the allocation of the buffer time has also become an important factor in the process of drawing the train timetable.Appropriate buffer time can prevent and reduce the propagation of initial delays,and can also effectively avoid redundancy and waste.First of all,this paper draws on the relevant research results on improving the robustness of train timetable at home and abroad in recent years,combs and elaborates the basic theories of train timetable robustness and buffer time,and analyzes the influencing factors of the two in detail,and then A clear entry point for the in-depth study of this article.Based on the actual national conditions and road conditions of our country,this paper establishes a compression model for the train timetable,and obtains the total buffer time capacity by compressing various diagram operations in the train timetable to standard operations.Then,after obtaining the total buffer time of each interval through the train timetable compression model,this paper introduces the knapsack problem model.The goal is to construct the optimal buffer time allocation model to maximize the corresponding value of the buffer time.When solving the optimal allocation model of the buffer time of the train timetable,this article focuses on the calculation method of the corresponding value of the buffer time.Considering that the purpose of setting the buffer time is to prevent the occurrence of delays or reduce the impact of delay propagation,set too much buffer time at a certain location.It will cause redundancy and waste and affect the line capacity,so this paper introduces a utility function into the objective function.Again,in view of the "passenger and freight common line" mode of my country’s existing railway lines,with the goal of transportation equilibrium,the newly allocated buffer time of each candidate area is obtained by using the buffer time optimization allocation model.After the buffer time is adjusted,the adjacent trains during the period,it can be adjusted through the optimization method of the train operation line,and the area of the train operation line is reserved.To provide a basis for train operations during peak hours or special seasons.When an emergency occurs in daily situations that causes a train to be delayed,in order to ensure the punctuality of the original train in the train timetable,virtual train lines can be temporarily deducted to ensure the punctuality of the train in the original train timetable,and finally realized the role of enhancing the robustness of the train timetable.Finally,this paper uses the Lanzhou-Longxi section of the Longhai Line in the fourth quarter of 2020 as a specific research example to verify.In order to judge the robustness of the train timetable after the optimized buffer time is allocated,this paper draws on the existing research and adopts the difference of the train timetable.The quality evaluation method evaluates and analyzes the calculation results of the examples,and the results show that in the example,the up direction is optimized by 7% and the downward direction is optimized by8.14%.The robustness of the train timetable is improved.