Collaborative Optimization Of Line Plan And Timetable For Additional High-Speed Trains

The passenger demand for high-speed railway in Spring Festival and other holidays increases significantly,and the railway companies usually adopt the measure of adding additional passenger trains(hereinafter referred to as "additional trains")to supplement the transport capacity and meet the passenger demand.Railway companies have implemented the "One Day One Timetable" program,which adjusts the daily line plan and train timetable based on the passenger demand,and appropriately increases the number of trains in the railway corridor with high passenger demand and tight transportation capacity to match the transportation capacity with the passenger demand.In this context,it's important to efficiently organize the operation of additional trains and optimize the transportation organization plan of additional trains.This paper analyzes the content of line plan and timetable and the relationship between them,and also proposes the necessity of collaborative optimization of the train line plan and train timetable in combination with the special characteristics of the additional trains.Constructing the control model with discrete-time method and designing the train flow simulation experiment is to understand the train flow characteristics and the operation rules of the railway system.Furthermore,different types of mathematical optimization models are constructed based on station-based passenger demand and OD(Origin-Destination)passenger demand respectively,in order to obtain additional trains' line plan and train timetable which have low transportation cost and good transportation service.The main contents and innovation points of this paper are organized as follows:(1)Modeling analysis of the traffic characteristics of train traffic flow based on discrete-time method.Based on the discrete-time method and the physical laws of train traffic flow,the train control equations are constructed and new formulas of acceleration,deceleration and the minimum headway are proposed.Based on the control principle of mobile blocking system and the operation rules of trains in the railway system,the control strategies of departure,entry,tracking and overtaking operation are proposed.In view of the occurrence principle of irregular events,the control strategies for handling different types of irregular events are proposed.The simulation algorithm is designed and it is applied to design train traffic flow experiment on the railway network including 32 stations and 42double-track segments.Results of our experiments show that the proposed control model and algorithm can effectively simulate the train traffic flow on the large-scale network,control the trains to perform various operations on the railway network and handle various types of irregular events.Based on the large-scale network train traffic flow simulation experiments,the influence of parameters on train traffic flow is analyzed.The experimental results prove that the number of trains,the minimum headway and irregular events have an impact on the clearing time of train traffic flow on the network.(2)The collaborative optimization of line plan and train timetable based on the station-based passenger demand.Based on the idea of collaborative optimization of line plan and train timetable,a mathematical optimization model is constructed at the macro level to collaborative optimize the number of trains,train type,stopping plan and arrival and departure time of trains at each station.Firstly,the space-time network is constructed,and the problem of collaborative optimization of the line plan and train timetable is transformed into a spacetime path optimization problem.Then,A bi-objective integer programming model is built with the objective function minimizing the difference between the passenger demand and the total transport capacity and the total train running time.A small-scale experiment is designed to verify the effectiveness of the proposed method,and the results show that the additional trains have increased the level of satisfaction of passenger demand from 54%to 95%.A large-scale experiment based on the data of Wuhan-Guangzhou high-speed railway is designed,and experimental results show that the total capacity provided by all trains after optimization meets 98.3% of the total passenger demand.It proves that the proposed method and model can be applied to solve the large-scale problem of additional trains.The impact of each parameter on the optimization results is analyzed by adjusting the parameters of the large-scale experiments.The experimental results show that the passenger seat utilization constraint can improve the equilibrium of the train loading capacity;the weight coefficient of the objective function has a significant impact on the number of additional trains and the degree of passenger demand satisfaction;the traffic capacity of line can be decreased by increasing the number of D trains(Normal multiple unit trains).(3)The collaborative optimization of line plan and train timetable based on the OD passenger demand.Considering the origin and destination of passengers,a collaborative optimization model is constructed based on the OD passenger demand,which optimizes the train operation zones,the number of trains,stopping plan,passenger distribution and arrival and departure time of the train at each station.This model introduces the decision variables of passenger distribution,operation zone and train sequence on the basis of the old model.A multi-objective nonlinear integer programming model is constructed with the objectives of minimizing the total running distance by trains,the total stopping time of trains and the difference between passenger demand and total transport capacity.The nonlinear model is transformed into linear model and it is solved.Small-scale experiments are designed and the effects of parameters on the experimental results are analyzed.The experimental results show that the parameters such as passenger seat utilization factor,minimum stopping time and minimum number of stops have significant effects on the transportation plans of the additional trains.Further,a large-scale experiment based on the data of Beijing-Shanghai high-speed railway is designed,and the results show that the additional trains reduced the unsatisfied passenger demand of19,757 before optimization to 23.It demonstrates that the proposed method can relieve effectively transportation pressure of railway companies on large-scale corridor.