| The high speed railway dispatching system is the nerve center of the whole train operation organization. It plays a critical role in ensuring the safety, punctuallty and efficiency of train operations. Advanced dispatching systems and train control systems are applied on Chinese high speed railway to guarantee the operational safety and efficiency. Therefore, trains run automatically under the controlling of these advanced systems in normal situation. However, trains are inevitably disrupted by external and internal factors in daily operations. Thus, they cannot run as scheduled. In a disturbanced situation, disrupted trains can recover due to the buffer time in the railway timetable. However, in a disrupted situation, a large number of trains deviate from the original timetable and some trains need to be canceled. To this end, dispatchers should reschedule disrupted trains manually and quickly to reduce the impact of the disruption on the whole train operations as well as to ensure the safety of train operations.Till now, in a disrupted situation, trains are mainly rescheduled manually by dispatchers with assistance from dispatching systems. Therefore, railway dispatchers have to put out effective train rescheduling strategies as soon as possible. In this situation, dispatchers face a heavy burden and it is difficult for them to make an effective train rescheduling plan in time due to their limited ability. To fulfill the requirement of practice and to make up the gap in this research area, this research focuses on real-time train rescheduling in the disrupted situation where one track or both tracks of a segment are blocked on a high speed railway. Mixed Integer Liner Programming models are formulated to solve the train rescheduling problem in a disrupted situation. Effective algorithms are utilized to quickly obtain the railway disposition timetable, which can assist the dispatchers to make decisions in real-time. The main contents of this paper are as follows:(1) Based on the definition of railway disturbance/disruption, we analyze the factors that influence the normal train operations. Thereafter, these factors are classified according to various criterions. Some typical railway accidents both at home and abroad are listed and the reasons are analyzed, from which we can see that accidents often occur. Finally, we analyze the content of train rescheduling in a disrupted situation in detail. We conclude that the train rescheduling problem in a disrupted situation mainly includes the train rescheduling in a completely segment blocked situation and train rescheduling in a partially segment blocked situation. which has made a foundation for the following research.(2) In a disrupted situation where both tracks of a segment are temporarily unavailable for a relatively long period of time, the train rescheduling problems for upside trains and downside trains can be separated if we assume upside (downside) trains can only use upside (downside) tracks in a station. In this research, train rescheduling problem is described by an event-activity network at a macroscopic level. A Mixed Integer Programming model is formulated to solve the train rescheduling problem for trains in one direction in a completely blocked situation. By retiming, reordering and canceling trains, disrupted trains are required to recover from the disruption as soon as possible. In our model, trains that need to stop at intermediate stations to wait for the disruption have to wait there until the disruption is really over. Thus, our disposition timetable is more rubost. Based on the feature of the problem, a two stage approach is applied to quickly solve the model and obtain good train rescheduling plans. Therefore, our research can provide the involved dispatchers with disposition timetable in real-time.(3) In a disrupted situation where both tracks of a segment are temporarily unavailable for a relatively long period of time, we can allow both upside trains and downside trains share the same siding in a station to further reduce the influence of the disruption on train operations. Based on this assumption, a Mixed Integer Programming model is formulated to solve the train rescheduling problem for trains in both directions. By stopping disrupted trains in appropriate stations during the disruption, retiming, reordering and canceling trains, we can prevent stopping trains from hindering running trains and decrease the impact of the disruption on train operations. To solve large practical problems, a rolling horizon approach is introduced, which can help to decompose our model and obtain train disposition timetables quickly.(4) Three practical train rescheduling strategies are usually applied in a disrupted situation where one track of a segment is temporarily unavailable. We desceibed the three train rescheduling strategies according to the practice. Three Mixed Integer Programming models are formulated for the three strategies separately. Considering the uncertainty of the duration of the disruption, trains are rescheduled gradually based on the latest information. Accordingly, the rolling horizon approach is applied to decompose our models as well as handling the uncertainty. The experiment results show that our approach can obtain good solutions in a short computation time for each disruption scenario. Therefore, we can not only assist the involved railway managers and dispatchers to choose the best train rescheduling strategy, but also afford them real-time disposition timetables.(5) in a seriously disrupted situation, it is not enougn to just rescnedule the railway timetable. The rolling stock is also needed to be rescheduled to ensure that each train in the disposition timetale has a proper rolling stock to use. We formulate the train rescheduling models while considering the capacity of the rolling stock. Effective algorithms are introduced to solve the models. Our approach can provide the dispatchers with more practical disposition timetables which are still feasiable considering the rolling stock circulation. |
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