1,720,980 research outputs found
Ein Schichtenmodell für den Entwurfsprozess der Eisenbahninfrastruktur
No full textFixed-interval timetables are central to the further development of rail networks because they better meet customers' needs. However, infrastructure is needed to make the service possible. It would be helpful to be able to derive the track topology directly from rail service, but to do this, several open questions need to be answered. This thesis aims to find and name these open questions for the design of service-oriented infrastructure. Inspired by ideas and discussions about the cycle of track topology design, a working hypothesis for improved integrated transport planning for a more transparent railway system design was developed to justify service-oriented infrastructure. Three research questions regarding the relationship between rail service and track topology were formulated from the working hypothesis. The method of design science research was utilised to answer the research questions. Design science research is centred around an artifact that is constructed in cycles. The developed artifact is a railway layer model with several layers between the track topology and the rail service. The design science research method began with assembling an initial artifact and modelling one layer per cycle upon the initial artifact. The modelling was done with an example railway network and the validating functions of the current layer in a cycle. The modelling was undertaken in the direction of rail service by beginning at the track topology layer. Reversing the direction after finishing the artifact was carried out to chart the railway infrastructure design process for a service-oriented infrastructure. As a first result, the layer model consisted of collections of data with a specific purpose. These collections were used to find a suitable reverse path for the design process for a service-oriented infrastructure. The second result was clusters of collections named motifs. There are eight motifs in the landscape of problems for direction rail service to track topology. Some motifs can already be considered solved, while others still require further research.Integrierte Taktfahrpläne spielen eine zentrale Rolle bei der Weiterentwicklung moderner Eisenbahnnetze, da sie den Bedürfnissen der Fahrgäste möglicherweise entgegenkommen. Um jedoch einen solchen Betrieb zu ermöglichen, ist eine geeignete Infrastruktur erforderlich. Die Möglichkeit, die Gleistopologie direkt aus einem Fahrplan abzuleiten, wäre von großem Nutzen, jedoch gibt es noch zahlreiche offene Fragen, die in diesem Zusammenhang beantwortet werden müssen. Ziel dieser Dissertation ist es, diese offenen Fragen zu identifizieren und einen Beitrag zur Gestaltung einer serviceorientierten Eisenbahninfrastruktur zu leisten. Ausgehend von bisherigen Überlegungen zur Zyklusgestaltung der Gleistopologie wird eine Arbeitshypothese vorgestellt, die eine verbesserte, integrierte Verkehrsplanung mit dem Ziel einer transparenten und serviceorientierten Infrastruktur vorschlägt. Auf dieser Grundlage werden drei zentrale Forschungsfragen formuliert, die das Zusammenspiel zwischen Fahrplan und Gleistopologie untersuchen. Zur Beantwortung dieser Fragen wird die Design-Science-Research-Methode angewendet, die sich auf die schrittweise Entwicklung eines Artefakts in iterativen Zyklen konzentriert. Das im Rahmen dieser Arbeit entwickelte Artefakt ist ein mehrschichtiges Modell des Eisenbahnsystems, das die verschiedenen Ebenen zwischen Gleistopologie und Fahrplan darstellt. Der Forschungsprozess begann mit der Erstellung eines Ausgangs-Artefakts, das in mehreren Zyklen weiterentwickelt wurde, wobei pro Zyklus jeweils eine weitere Schicht modelliert wurde. Diese Modellierung erfolgte anhand eines Beispiel-Eisenbahnnetzes, wobei jede Schicht auf ihre Validität hin überprüft wurde. Der Prozess startete bei der Gleistopologie und führte schrittweise zum Fahrplan, bevor die Reihenfolge umgekehrt wurde, um die serviceorientierte Gestaltung der Infrastruktur zu entwickeln. Als vordergründiges Ergebnis liefert das Schichtenmodell eine Sammlung spezifischer Datensätze, die zur Entwicklung eines Rückwärtspfads für den Entwurfsprozess einer serviceorientierten Infrastruktur genutzt werden können. Das zweite Ergebnis besteht in der Identifizierung von acht zentralen Problemstellungen ("Motive") im Zusammenspiel von Fahrplan und Gleistopologie. Einige dieser Motive sind bereits weitgehend gelöst, während andere noch weiterer Forschung bedürfen
A delay propagation algorithm for large-scale railway traffic networks
No full textIn scheduled railway traffic networks a single delayed train may cause a domino effect of secondary delays over the entire network, which is a main concern to planners and dispatchers. This paper presents a model and an algorithm to compute the propagation of initial delays over a periodic railway timetable. The railway system is modelled as a linear system in max-plus algebra including zero-order dynamics corresponding to delay propagation within a timetable period. A timed event graph representation is exploited in an effective graph algorithm that computes the propagation of train delays using a bucket implementation to store the propagated delays. The behaviour of the delay propagation and the convergence of the algorithm is analysed depending on timetable properties such as realisability and stability. Different types of delays and delay behaviour are discussed, including primary and secondary delays, structural delays, periodic delay regimes, and delay explosion. A decomposition method based on linearity is introduced to deal with structural and initial delays separately. The algorithm can be applied to large-scale scheduled railway traffic networks in real-time applications such as interactive timetable stability analysis and decision support systems to assist train dispatchers
Railway timetable rescheduling with flexible stopping and flexible short-turning during disruptions
No full textRailway operations are vulnerable to unexpected disruptions that should be handled in an efficient and passenger-friendly way. To this end, we propose a timetable rescheduling model where flexible stopping (i.e. skipping stops and adding stops) and flexible short-turning (i.e. full choice of short-turn stations) are innovatively integrated with three other dispatching measures: retiming, reordering, and cancelling. The Mixed Integer Linear Programming model also ensures that each train serving a station is ensured with a platform track. To consider the rescheduling impact on passengers, the weight of each decision is estimated individually according to the time-dependent passenger demand. The objective is minimizing passenger delays. A case study is carried out for hundreds of disruption scenarios on a subnetwork of the Dutch railways. It is found that (1) applying a mix of flexible stopping and flexible short-turning results in less passenger delays; (2) shortening the recovery duration mitigates the post-disruption consequence by less delay propagation but is at the expense of more cancelled train services during the disruption; and (3) the optimal rescheduling solution is sensitive to the disruption duration, but some steady behaviour is observed when the disruption duration increases by the timetable cycle time
Identifying effective guaranteed connections in a multimodal public transport network
No full textMinimizing transfer waiting time is important in making public transport networks more attractive. A guaranteed transfer, with the departing vehicle waiting on moderately delayed arriving vehicles at a transfer node, is an effective way to reduce waiting times at transfers between low frequency public transport lines. This comes at the cost of a new delay for some non-transferring passengers. The method described in this paper, based on max-plus algebra, classifies potential connections based on their feasibility for given initial delays, in order to help operational decisions on-line and to assist public transport companies off-line in identifying transfers vulnerable to delays. A case study shows the applicability of the approach for a real-life multimodal network
A cycle time optimization model for generating stable periodic railway timetables
No full textAs train passengers expect a high degree of reliability from a railway network with minimal delays, during the timetabling process planners need to balance the goals of maximizing the offered capacity and delay resistance. This is often done in a two-step process where first a feasible timetable is found for a given line structure, and consecutively the stability of this timetable is evaluated and local modifications are performed to the timetable. This paper describes an optimization method to find a feasible periodic timetable that also ensures maximum stability for heterogeneous railway networks. The model is capable to handle flexible train orders, running and dwell times, and overtaking locations. We use the minimum cycle time of the periodic timetable as an indicator for stability, and define an optimization problem with this minimum cycle time as the objective function to be minimized. We also present dimension reduction methods and an iterative optimization approach to improve the mathematical optimization process. We show the applicability of the approach with case studies on the central part of the Dutch railway network
Combined line planning and train timetabling for strongly heterogeneous railway lines with direct connections
No full textRail systems have been developing rapidly in recent years aiming at satisfying the growing passenger demand and shortening passenger travel time. The line planning problem (LPP) and train timetabling problem (TTP) are two key issues at the strategic level and tactical level, laying the foundation of a high-level service quality for railway operation. In this paper, a multi-frequency LPP (MF-LPP) model and a multi-period TTP (MP-TTP) model are introduced for direct connections, with consideration of both periodic and aperiodic nature to meet strongly heterogeneous train services and reduce the capacity loss of train operating companies. A combined LPP and TTP method is designed considering timetable robustness, timetable regularity, and passenger travel time. For a given line pool, a multi-objective mixed integer linear programming model for the MF-LPP is formulated to obtain a line plan with multiple line frequencies by minimizing travel time, empty-seat-hour and the number of lines. Using the acquired line plan from the previous step, a MP-TTP model is proposed to achieve the minimal travel time, the maximal timetable robustness and the minimal number of overtakings. The two models work iteratively with designed feedback constraints to find a better plan for the rail transport system. Numerical experiments are applied to verify the performance of the proposed model and solution approach
Stable and robust train routing in station areas with balanced infrastructure capacity occupation
No full textRouting trains through busy railway station layouts is an important part of the timetabling process. For each train, a feasible route has to be determined to provide reliable operations, given the arrival and departure times at stations. In this paper, we propose a model for stable and robust train routing with the goal to minimize capacity occupation and maximize robustness. We define a multi-objective optimization problem and provide the heuristic RouteCare based on a max-plus automata model and a delay propagation model. We consider microscopic infrastructure to guarantee practical feasibility. The performance of the proposed algorithm is demonstrated on real-life instances of the Dutch railway network. The generated solutions outperformed the variants of RouteCare that independently maximize stability or robustness by 10.4% and 9.5%, respectively. In addition, RouteCare showed that even for the same number of resources used, a more robust route plan can be found that uses the station capacity more efficiently
Multiple-phase train trajectory optimization with signalling and operational constraints
No full textThe train trajectory optimization problem aims at finding the optimal speed profiles and control regimes for a safe, punctual, comfortable, and energy-efficient train operation. This paper studies the train trajectory optimization problem with consideration of general operational constraints as well as signalling constraints. Operational constraints refer to time and speed restrictions from the actual timetable, while signalling constraints refer to the influences of signal aspects and automatic train protection on train operation. A railway timetable provides each train with a train path envelope, which consists of a set of positions on the route with a specified target time and speed point or window. The train trajectory optimization problem is formulated as a multiple-phase optimal control model and solved by a pseudospectral method. This model is able to capture varying gradients and speed limits, as well as time and speed constraints from the train path envelope. Train trajectory calculation methods under delay and no-delay situations are discussed. When the train follows the planned timetable, the train trajectory calculation aims at minimizing energy consumption, whereas in the case of delays the train trajectory is re-calculated to track the possibly adjusted timetable with the aim of minimizing delays as well as energy consumption. Moreover, the train operation could be affected by yellow or red signals, which is taken into account in the train speed regulation. For this purpose, two optimization policies are developed with either limited or full information of the train ahead. A local signal response policy ensures that the train makes correct and quick responses to different signalling aspects, while a global green wave policy aims at avoiding yellow signals and thus proceed with all green signals. The method is applied in a case study of two successive trains running on a corridor with various delays showing the benefit of accurate predictive information of the leading train on energy consumption and train delay of the following train
A three-level framework for performance-based railway timetabling
Full text linkThe performance of railway operations depends highly on the quality of the railway timetable. In particular for dense railway networks it can be a challenge to obtain a stable robust conflict-free and energy-efficient timetable with acceptable infrastructure occupation and short travel times. This paper presents a performance-based railway timetabling framework using an integrated approach on three levels: microscopic, macroscopic and a corridor fine-tuning level, to compute a timetable explicitly driven by the above mentioned performance indicators. A case study on the Dutch railway network illustrates the feasibility of this approach to achieve the highest timetabling design level.Transport & PlanningCivil Engineering and Geoscience
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