Study On The Train Rescheduling And Speed Control Problem In Case Of Decreased Traffic Capacity On One-side Railway Track

Under the guidance of the transportation policies in China in the new era,high-speed railway networks are increasingly expanded.More and more cities in China are connected by high-speed railways.In fact,high-speed railways are constructed in natural environment,which means that sometimes train operations can be influenced unavoidably by natural disaster or other contingencies.The railway operation company in China are facing big pressure to ensure the safety and punctuality of the trains in the enormous high-speed railway networks.Train rescheduling problem is to reschedule trains in abnormal situations to reduce train delay while keeping operation safety.Meanwhile,Chinese government advocates developing sustainable transportation systems for public.Studies on developing new methods to optimize the train speed trajectories for energy-efficient train operation is of vital significance in terms of building sustainable railway systems.This thesis combines two important aspects of train rescheduling and energy-efficient train operation.Moreover,this thesis tries to explore integrated methods of train rescheduling and energy-efficient train operation,which is called the train rescheduling and speed control method.The contributions of this thesis are as follows.(1)The train rescheduling problem on high-speed railway lines in the situation where contingencies occur and lead to sudden deceleration of some trains is studied.First,an adaptive rescheduling strategy(AR-S)which can adaptively adjust the paths of trains to optimal is developed.The proposed strategy is based on the formulas of train delay time.Second,the traditional rescheduling strategy(TR-S)which does not allow any trains to adaptively decide their paths is mentioned as a sharp contrast to AR-S.Furthermore,a performance evaluation criterion is designed to evaluate the effectiveness of the train rescheduling approaches.Finally,numerical experiments carried out on Beijing-Tianjin intercity high-speed railway show that AR-S can reduce the total delay of trains up to 24%compared with TR-S.(2)The problems of train rescheduling with speed control under temporary speed restrictions on high-speed railways are studied.A two-stage optimization approach is proposed to optimize punctuality,energy efficiency,and riding comfort of multiple trains.For the first stage(i.e.,stage 1)of the proposed approach,the objective is to minimize total travel time of trains,with rescheduling measures such as retiming,reordering,and rerouting of trains.Mixed-integer linear programing model(MILP)is formulated in stage1,and the main decision variables of the model are the arrival times of trains at each block section.Single-train trajectory optimization(STTO)is applied to study the optimal control problem in the second stage(i.e.,stage 2),which is re-formulated as a MILP model using piecewise affine functions.The objective of stage 2 is to optimize the speed trajectories of train for energy efficiency and riding comfort.The MILP models in this paper are solved by sophisticated optimization software in short computing times.Finally,we carry out case studies on the Beijing-Tianjin intercity high-speed railway in China to testify the effectiveness and efficiency of the proposed approach.The proposed approach is able to generate rescheduling solutions in downstream direction for the involved 77 downstream trains,and speed trajectory of each train can be re-optimized for energyefficiency and riding comfort.(3)To reschedule trains with speed control in the situation where one of the two tracks is blocked.Mathematical models are built and solved in a two-stage framework.Similarly,mathematical models in the first stage are to optimize the total train travel time.The arrival times of train at each block section,the train sequences and the train paths are all optimized in the first stage for reducing train delay.The safety distances between every pair of two trains can be guaranteed in real time in the first stage.Based on the solutions of stage 1,mathematical models in stage 2 are to optimize train speed trajectories for energy efficiency and riding comfort.In stage 2,optimal control models are built and transformed into mixed-integer linear programming models,which are solved by commercial software in short computing time.Finally,case studies are carried out based on the timetable for a whole day on the Beijing-Tianjin intercity high-speed railway line.Results show that the proposed approach is able to generate rescheduling solutions for the involved 40 downstream and 41 upstream trains.The speed trajectories for both upstream and downstream trains are also re-optimized in short computing times.There are 41 pictures,17 tables and 70 references.