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Abstract
Planning railway operations is not a simple task as it entails solving multiple interdependent
optimization problems. These problems have been subject to study in the literature for the last
few decades, and are still profoundly researched. The robustness of a plan or schedule denotes the
ability to absorb or withstand unexpected events such as delays. Making robust plans is central in
order to maintain a safe and timely railway operation. This thesis focuses on reactive robustness,
i.e., the ability to react once a plan is rendered infeasible in operation due to disruptions. In such
time-critical situations, new plans must be found quickly. Integration of the different planning
problems is also considered in this thesis as these problems are strongly interdependent in many
cases. In contrast, finding feasible plans for each problem in isolation can lead to an overall
infeasibility, e.g., during a disruption the updated timetable may be impossible to realize due to
the lack of rolling stock units at certain positions. It is important to avoid creating problems for
later or subsequent planning stages.
Several railway problems are studied in this thesis. The main contributions are summarized in
individual chapters, some of which are papers that have been submitted to international scientific
journals in operations research. The problems have been formulated as optimization problems
and solution methods have been proposed to solve them using optimization theory and various
solution techniques. In collaboration with industry and academic partners real-life and realistic
data has been used to benchmark and test the solution methods.
A central actor and theme of the thesis is the rolling stock running on the railway networks. A
public timetable is given, and in order to service the departures and passengers a rolling stock
schedule (or circulation) is sought that provides the best compromise between operational cost,
robustness, contract requirements and passenger satisfaction. In between train services the rolling
stock units must be parked in the available depots. As trains cannot overtake each other easily,
special attention must be given to avoid conflicting movements. Furthermore, rolling stock units
are heavy and consume a considerable amount of energy in operation; with proper optimization
tools a significant amount of the energy can be saved. A prompt optimization of individual train journeys helps the driver to drive efficiently and enhances robustness in a realistic (dynamic)
environment.
Four international scientific prizes have been awarded for distinct parts of the research during
the course of this PhD project. The first prize was awarded for work during the \2014 RAS
Problem Solving Competition", where a freight yard optimization problem was considered. The
second junior (PhD) prize was awared for the work performed in the \ROADEF/EURO Challenge
2014: Trains don't vanish!", where the planning of rolling stock movements at a large station was
considered. An honorable mention (and second place) was awarded in recognition for excellent work
in the \Discrete Optimization Challenge", where the aim was to minimize energy consumption in
timetables. Finally, a second place was awarded in the \2015 RAS Student Paper Award", where
a comparison of solution methods for planning shunting yard movements was considered.
Original language | English |
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Publisher | DTU Management Engineering |
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Number of pages | 233 |
Publication status | Published - 2015 |
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Dive into the research topics of 'Reactive Robustness and Integrated Approaches for Railway Optimization Problems'. Together they form a unique fingerprint.Projects
- 1 Finished
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Integreret disponering/genopretning af togdrift
Haahr, J. T. (PhD Student), Pisinger, D. (Main Supervisor), Larsen, J. (Supervisor), Røpke, S. (Examiner), Huisman, D. (Examiner) & Borndörfer, R. (Examiner)
Technical University of Denmark
01/08/2012 → 11/12/2015
Project: PhD