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Title: Optimal control of traffic flow at a conflict area in railway network
Author: Ho, Tin Kin
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1994
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A railway network may contain various kinds of track configurations. Some sections of tracks can be approached by traffic from two or more directions and there will be dispute as to the assignments of right of way. A traffic conflict occurs when two or more trains are approaching the same section of track, which is termed a conflict area, and they need to alter their progress to avoid collision. If the timetable is fully observed, there should not be any conflicts. However, when a train has been delayed for some reason, it may approach a conflict area so late that the progress of other train(s) near the conflict area is affected. Delays will then be inflicted on the trains involved as a result of conflict. Current practices to assign the right of way at conflict areas usually achieve an orderly and safe passage of the trains, but do not attempt to reduce the delays imposed on the trains. As the demands on the quality of railway services are always rising, any causes of delays should be avoided or at least the delays minimised. This thesis describes the development of a delay-optimised traffic controller which resolves the conflicts in a railway network by producing a policy of right-of-way assignments with minimum total weighted delay imposed on the trains. Dynamic programming is employed to conduct the optimisation process. In order to evaluate the costs during optimisation, an event-based traffic flow model is used to simulate the consequences of certain assignments of right-of-way. Various tests have been carried out to assess the performance of the controller under different traffic conditions. It has been shown that the policies produced by the controller inflict about 10 % less total weighted delays on the trains when compared with a commonly used practice, first come-first served. Hence, while the controller can produce policies with minimal delays imposed on the trains, first come-first served is in fact a reasonable means to deal with a single converging junction. Furthermore, the controller is capable of producing the optimal policies for most conflicts within 2-3 seconds so that it can be used in real-time applications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available