# An Integrated Optimization Method of High-Speed Railway Rescheduling Problem at the Network Level  
[PERSON]  
1 The School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China; [EMAIL_ADDRESS] (W.Z.); [EMAIL_ADDRESS] (L.Z.); [EMAIL_ADDRESS] (Y.X.); [EMAIL_ADDRESS] (C.H.); [EMAIL_ADDRESS] (Y.M.); 2
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[PERSON]  
1 The School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China; [EMAIL_ADDRESS] (W.Z.); [EMAIL_ADDRESS] (L.Z.); [EMAIL_ADDRESS] (Y.X.); [EMAIL_ADDRESS] (C.H.); [EMAIL_ADDRESS] (Y.M.); 2
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D hub stations, considering they connect two railway lines. In general, there are train set depots near the hub stations, and the depots are responsible for train set parking and maintenance. And also, there are some train sets in the depots deployed by the operation department in case of emergencies, and we call these train sets standby train sets. When an emergency occurs, the operators can dispatch these standby train sets to replace the affected trains and perform their scheduled operation plans.  
Figure 2 is a three-dimensional graph that describes the spatiotemporal operation process of the scheduled operation plans. The plane composed of the x-axis and y-axis represents the railway network structure in the real world, and the z-axis represents time. Different colorful lines represent different trains. There are five trains in the figure: Train  
Figure 3 shows some dispatching methods to deal with the influence of emergencies. In this figure, different colorful lines represent different trains. If train 1 has an equipment failure when it operates in sections B-C, it will have to stop in the section and wait for rescue. Then, trains 2, 3, and 4 will be delayed for a period of time, as the dash lines show, because they cannot depart from station A until train 1's rescue operation is finished.  
As mentioned above, train 2 and train 3 share the same train sets. If train 2 is delayed for a short period of time, considering the rest turnback time is enough to finish necessary operations, train 3 will not be influenced by the delay, as shown in Figure 3. But if train 2 is delayed for a long period of time, considering the rest of the connecting time is not enough to finish necessary operations, the operator will have to dispatch a standby train set to undertake the operation plan of train 3, or train 3 will also be delayed. So, we can see that the train timetable and train set circulation plan are closely related to the rescheduling problems, and it is necessary to reschedule these two aspects together.  
Train 3 and train 4 are two delayed short trains. In order to improve operation efficiency, they can be coupled at station A and form a new long train called train 6. Train 2 operates from station A to station D. And then, train 6 is decoupled from train 3 and train 4 at station D.  
Besides dispatching standby train sets and coupling short trains, some other methods are also efficient, such as adjusting the arrival time and departure time of the train, changing the sequence of delayed trains, and canceling trains.  
Above all, the operators should take all kinds of dispatching methods into consideration when facing an emergency and propose a complete scheme composed of some suitable methods according to the time, location, and other factors of the emergency so as to make the train operation return to normal and reduce the loss of the delay for passengers.