Inserting Extra Train Services on High-Speed Railway

With the aim of supporting future traffic needs, an account of how to reconstruct an existing cyclic timetable by inserting additional train services will be given in this paper. The Timetable-based Extra Train Services Inserting (TETSI) problem is regarded as an integration of railway scheduling and rescheduling problem. The TETSI problem therefore is considered involving many constraints, such as flexible running times, dwell times, headway and time windows. Characterized based on an event-activity graph, a general Mixed Integer Program model for this problem is formulated. In addition, several extensions to the general model are further proposed. The real-world constraints that concerning the acceleration and deceleration times, priority for overtaking, allowed adjustments, periodic structure and frequency of services are incorporated into the general model. From numerical investigations using data from Shanghai-Hangzhou High-Speed Railway in China, the proposed framework and associated techniques are tested and shown to be effective

A short-turning policy for the management of demand disruptions in rapid transit systems

Rapid transit systems timetables are commonly designed to accommodate passenger demand in sections with the highest passenger load. However, disruptions frequently arise due to an increase in the demand, infrastructure incidences or as a consequence of fleet size reductions. All these circumstances give rise to unsupplied demand at certain stations, which generates passenger overloads in the available vehicles. The design of strategies that guarantee reasonable user waiting time with small increases of operation costs is now an important research topic. This paper proposes a tactical approach to determine optimal policies for dealing with such situations. Concretely, a short-turning strategy is analysed, where some vehicles perform short cycles in order to increase the frequency among certain stations of the lines and to equilibrate the train occupancy level. Turn-back points should be located and service offset should be determined with the objective of diminishing the passenger waiting time while preserving certain level of quality of service. Computational results and analysis for a real case study are provided.Junta de Andalucía P09-TEP-5022Natural Sciences and Engineering Research Council of Canada (NSERC) 39682-1

Estimation of run times in a freight rail transportation network

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 49-51).The objective of this thesis is to improve the accuracy of individual freight train run time predictions defined as the time between departure from an origin node to arrival at a destination node not including yard time. A correlation analysis is conducted to identify explanatory variables that capture predictable sources of delay and influence run times for use in a regression model. A regression model is proposed utilizing the following explanatory variables: rolling historical average, congestion window, meets, passes, overtakes, direction, arrival headway, and departure headway to predict train run times. The performance of the proposed regression model is compared against a baseline simple historical averaging technique for a two year period of actual train operational data. The proposed regression model, though subject to specific limitations, offers substantial improvements in accuracy over the baseline technique and is recommended as justifying further exploration by the railroad to ultimately enable more accurate train schedules with subsequent improvements in railroad capacity, customer service, and asset utilization.by Kunal Bonsra and Joseph Harbolovic.M.Eng.in Logistic

Verfahren zum Einfügen der zusätzlichen non-zyklischen Pfade in die bestehenden zyklischen Fahrpläne

With the development of high-speed railway (HSR), cyclic timetable shows many advantages. However, the pure cyclic timetable is not suitable in China's HSR. Consequently, a hybrid timetable concept named "cyclic + non-cyclic" timetable is proposed, with a cyclic core timetable in which some trains are inserted as non-cyclic trains. Nowadays, the cyclic timetables have been well developed but the technique of inserting additional train paths is still a significant demand for research. The Adding Train Paths (ATP) problem firstly is an integration of timetable scheduling and rescheduling problem. Therefore it is considered involving many general constraints, such as flexible running time, dwell time and headways. Based on an event-activity graph, a general mixed integer program model for the ATP problem is formulated. In addition, several real-world constraints that concerning the acceleration and deceleration time, priority for overtaking, station capacity, allowed adjustments, periodic structure and frequency of services are incorporated into the general model. In order to get a new timetable that with low deviations to the initial services and high quality of the performance to the additional trains, objective functions of minimizing travel time, minimizing total adjustments, minimizing the makespan and maximizing the robustness of the new timetable are discussed in this thesis. More importantly, many additional trains may not be inserted because of a shortage of train-sets. So how to cover the entire trains with minimum train-sets must be also taken into account in this problem. The train-set circulation in the ATP problem is decomposed to two sub-problems. (i) For initial trains, the initial train-set route is assumed to be fixed; it is solved as a rescheduling problem of a tight constraint to keep the current circulation. (ii) For additional trains, it is a train-set planning problem to cover all the additional trains with minimal number of train-sets. In order to solve the problem in a reasonable time, we start from fixed train-set route, and then apply flexible train-set route that provides possible alternative turning activities to decrease the waiting time of a train-set in an overnight turn-around. Case studies based on Shanghai-Hangzhou HSR line in China investigate the proposed framework and associated techniques. Meanwhile, the performances of various settings are compared to analyse the affecting factors to this specific problem.Zusammen mit der Entwicklung von Hochgeschwindigkeitsverkehr (HGV) hat der zyklische Fahrplan als sehr vorteilhaft bewiesen. Allerdings ist der zyklische Fahrplan für HGV in China nicht geeignet. Demzufolge wird ein Hybrid-Fahrplan Konzept mit „zyklisch + non-zyklisch“ vorgeschlagen. Mit dem zyklischen Fahrplan als Basis werden neue non-zyklischen Pfade eingefügt. Der zyklische Fahrplan wird bereits intensiv geforscht. Beim Einfügen von zusätzlicher non-zyklischen Pfade besteht jedoch großer Forschungsbedarf. Dieses Problem umfasst sowohl den Bereich der Planung als auch der Umplanung von Fahrplan. Mehrere Restriktionen werden berücksichtigt, z.B.: flexibel Fahrzeit, Haltezeit und Zugfolgezeit. Basiert auf Event-Activity-Graph, ein generisches gemischtes integrales Modell wird entwickelt. Zusätzlich werden die praxisrelevanten Restriktionen wie Beschleunigungszeit, Bremszeit, Priorität der Züge, Anzahl der Bahnhofsgleise, zulässige Verschiebung der Abfahrtszeit, periodische Struktur und Taktfrequenz mitbetrachtet. Um ein neuer Fahrplan mit einer geringen Verschiebung der Abfahrtszeit und zugleich eine hohe Qualität der zusätzlichen Züge zu ermöglichen, wird in dieser Arbeit die folgenden Kriterien als Zielfunktionen untersucht: Reisezeit, Summe der gesamten Zeitverschiebung, Spannbreite der Zeitverschiebung und Robustheit der Fahrplan. Die Anzahl der zusätzlichen non-zyklischen Pfade hängt wesentlich von der Anzahl der Züge ab, welche noch verfügbar sind. Daher ist ein optimaler Fahrzeugumlaufplan für die zusätzlichen Zugfahrten ein wichtiges Zielkriterium. Umlauf der bestehenden Zugfahrten und der zusätzlichen Zugfahrten werden separat betrachtet. (i) Bei der bestehenden Zugfahrten wird keine Änderung an Fahrzeugumlauf vorgenommen, auch nach Verschiebung der Abfahrtszeit bleibt der Umlauf unverändert. (ii) Für die zusätzlichen Zugfahrten wird die Anzahl der benötigen Züge minimiert. Um die Aufgabe in einer annehmbaren Rechenzeit zu lösen, werden anfangs die zusätzlichen Zugfahrten, deren Laufweg mit den zyklischen Zugfahrten identisch ist, untersucht. Anschließend werden weitere Zugfahrten mit flexiblen Laufweg eingefügt, welche durch Wenden im Unterwegsbahnhof die Wartezeit bzw. Aufenthaltszeit über Nacht am Endbahnhof möglichst reduzieren kann. Als Fallstudie wird HGV Shanghai-Hangzhou in China untersucht. Die Rechenzeiten von der unterschiedlichen Parametereinstellungen werden während der Untersuchung getestet, analysiert und verglichen