Simulation For Train Traffic Tlow And Optimization For Train Scheduling Problems

In recent years,rail transit has been rapid development for its low-pollution and efficiency,but it also faces severe challenge as the limited rail transit capacity,energy and other resources.Therefore,how to use the existing infrastructure resources to improve the operational efficiency,and reduce its energy consumption are the new issues in China's rail transport system.In view of the above issues,this dissertation systematically studies the rail transit by the means of simulation and optimization approach from many aspects,including the analysis of characteristics of train traffic flow,train timetabling and routing integrated optimization as well as the energy saving operation.The detailed contents of the research include:(1)Modeling and analysis for urban rail traffic flow with consideration of velocity effect.This paper firstly proposes a new calculation formula of the minimum tracking distance between adjacent two trains under the moving block system.Based on cellular automata simulation model,this paper establishes a simulation model for urban rail traffic flow.Numerical experiments are executed on a rail line with 3 stations(only has 1 platform at the intermediate station)and 2 sections.The results show that the train length,the traffic density,the dwell time at stations have a great influence on the train operation efficiency.By setting the reasonable departure intervals for heterogeneous traffic flow with different train length,the train delay can be effectively reduced.The train delay increases with train departure time intervals reduce as that train density increases on the rail line.While the train delay increases with the fixed dwell time at the intermediate station increases.In addition,considering preceding train velocity can effectively shorten the minimum departure intervals,which is conducive to improving the line capacity and ease the traffic pressure of urban rail system.(2)Modeling and analysis for heterogeneous traffic flow on high-speed railway line.Based on the discrete-time simulation model,this paper establishes a new simulation model for heterogeneous train traffic flow on high-speed railway line with consideration of velocity effect.Four effective train operation control strategies are developed to realize train moving,braking,and overtaking operation,including departing strategy,traveling strategy,braking strategy and overtaking strategy.The simulation results show that reducing the dwell time at stations can improve the rail line capacity and the average speed of trains,while shorten the train departure intervals can improve the track line capacity but may cause more delay.Besides,a longer section length and a higher ratio of the fast train can increase the average running speed of the train on the line.(3)Train routing and timetabling problem for heterogeneous train traffic with switchable scheduling rules.This paper proposes a mathematical model for the train routing and timetabling problem that allows a train to occasionally switch to the opposite track when it is not occupied,which we define it as switchable scheduling rule.The layouts of stations are taken into account in the proposed mathematical model to avoid head-on and rear-end collisions around stations.In this paper.the train timetable could be scheduled by three different scheduling rules,i.e.,no switchable scheduling rule(No-SSR)which allows trains switching track neither at stations and segments,incomplete switchable scheduling rule(In-SSR)which allows trains switching track at stations but not at segments,and complete switchable scheduling rule(Co-SSR)which allows trains switching track both at segments and stations.Numerical experiments are carried out on a small-scale railway corridor and a large-scale railway corridor based on Beijing-Shanghai high-speed railway(HSR)corridor respectively.The results of case studies indicate that Co-SSR outperforms the other two scheduling rules.It is also found that the proposed model can improve railway track utilization rate and train operational efficiency.(4)An integrated micro-macro approach for high-speed railway energy-efficient timetabling.Energy efficiency is an important factor in train operations that is rarely considered in the train timetable design process.This paper aims to investigate the possibilities to better incorporate energy-efficient train operations into railway timetables.A non-liner mathematical model with multi-objective of minimize train travel time and energy consumptions is formulated in this paper at beginning.Then,this paper decompose this origin problem since it is difficult to deal with this NP-hard problem.First,a discrete space-time-speed(STS)network is constructed to take the train speed into account.Second,a segment-level train trajectory optimization approach is developed,followed by the dynamic headway requirement between two consecutive trains at the same segment.An integrated train timetabling and speed control optimization model is formulated based on network flow balance theory in the STS network.Further,a fast algorithm is designed to find the near-optimal solution.The numerical experiments demonstrate that the developed approach provides better outcomes than the benchmark case in terms of both train journey time and energy consumption.