## 1 Introduction
However, the TRP and the TTP are more difficult to solve due to the scale of the problem in long distance HSR lines. In the normal approach, a train timetable is scheduled at first, to meet the passenger travel demands. Then the train-set circulation plan is scheduled according to the timetable. The disadvantage is, as mentioned above, that it leads to a waste of resources. Moreover, if the operation department only adjusts the timetable to meet the new state requirements, it will affect the satisfaction of passenger travel demands too. It is very difficult to solve the train timetable and the train-set circulation plan directly at the same time because the scale of the problem is too huge for long distance HSR lines and the time consumption will be unacceptable. The approach proposed in this paper aims to meet the demands of passengers as much as possible, without affecting the robustness of the implementation of the new timetable, and avoid the waste of resources. We calculated the train-set circulation plan and stop plan respectively, and finally matched them to obtain the timetable. The scale of each problem is smaller than the overall problem, which is easy to solve. The approach framework used in this paper is shown in Figure 4.  
As shown in Figure 4, we need the structure of the HSR, the operation safety parameters of the HSR, the position of the train-sets in the new state and the old state, and the travel demand of passengers before scheduling the transition timetable and the train-set circulation plan. The first step is to calculate the primary train-set circulation plan according to the position and state data of the train-set, the structure of the HSR and the operation safety parameters. We established a profit function according to the full load ratio of trains in different sections. The higher the load rate of the train, the higher the profit. Based on the  
Figure 4: Framework of the approach. profit function, we build an integer programming model with profit maximization as the goal and use CPLEX to solve. The plan obtained in this step is called the primary train-set circulation plan, which will be used in the third step to match with the stop plan. The second step is to calculate the stop plan according to the structure of HSR, operation safety parameters and passenger travel demands. The calculation of the stop plan should be based on the service plan. If a train arrives, departs, or passes through a station, we call the train serves the station. In the service plan, we define the minimum quantity of trains that stop at each station. Moreover, the quantity of trains is calculated by decomposing the passenger travel demands. The stopping plan here is used to match the train-sets of the primary train-set circulation plan. The third step is to match the primary train-set circulation plan and stop plan, based on a genetic algorithm (GA). In order to save time, we calculate the train timetable according to the operation safety parameters after the matching scheme is obtained by the GA. We adjust the operation lines beyond the operating time range, to output the final timetable and the train-set circulation plan that meets the operational requirements. The main contributions of this paper to the study of the TRP and the TTP are as follows:  
1. An integer programming model based on profit function was designed, and CPLEX was used to solve the primary train-set circulation plan in a very short time. 2. Based on the decomposition method of passenger travel demands, the service plan is constructed. We use CPLEX to solve the model and obtain the stop plan. 3. We proposed a GA to calculate the matching relationship of the primary train-set circulation plan and the stop plan, then calculate and adjust the timetable according to the safety operating requirements. The rest of the paper is as follows: In the second section, we summarize the existing research.