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Impacts of infrastructure, timetable and perturbations in operation of double-track railway lines with mixed traffic
KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301). KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. (Tågtrafikgruppen)
2010 (English)In: 12th World Conference on Transportation Research 2010, 2010Conference paper, Published paper (Refereed)
Abstract [en]

Delays play a central role in railway operation. They are of great importance both for customers and operators. They are direct measures of quality and reliability and hereby also an important factor for the competitiveness of the entire railway. Indirectly, the delays also affect quantitative factors such as capacity, i.e. the number of trains that can be (practically) operated. For these reasons, analysis of delays and delay propagation is an essential part of railway operations research.

The up-coming deregulation of railway traffic means that completely mixed traffic can be foreseen on the Swedish railway network. This article shows how the delays on a double-track railway line, operated with mixed traffic, are affected by infrastructure, timetable and primary delays. Experimental design, simulation and response surface metamodelling are applied in a multi-factor simulation experiment with nine factors.

The combination of simulation and experimental design makes it possible to draw general conclusions from a limited number of simulated variants and this type of multi-factor analysis is essential to an understanding of the railway as an operational system. The derived metamodels may also be used in different types of planning processes.

The metamodels show that speed and frequency factors have a great impact on delays. Freight train speed and the frequency of service of high-speed trains in particular turned out to be important. Perturbation factors, i.e. entry delays, were found to affect the delays less. Neither does the distance between adjacent overtaking stations in itself affect the delays. However, the inter-station distance still affects delays through interactions with other factors.

Place, publisher, year, edition, pages
2010.
Keyword [en]
Double-track, timetable, railway operation, railway capacity, experimental design, simulation, delays, reliability
National Category
Civil Engineering
Research subject
Järnvägsgruppen - Kapacitet
Identifiers
URN: urn:nbn:se:kth:diva-12725OAI: oai:DiVA.org:kth-12725DiVA: diva2:318286
Conference
12th World Conference on Transportation Research, Lisbon, Portugal
Projects
Framtida infrastruktur och kvalitet i tågföring
Note
QC20100622Available from: 2010-05-07 Created: 2010-05-07 Last updated: 2012-02-28Bibliographically approved
In thesis
1. Railway operation analysis: Evaluation of quality, infrastructure and timetable on single and double-track lines with analytical models and simulation
Open this publication in new window or tab >>Railway operation analysis: Evaluation of quality, infrastructure and timetable on single and double-track lines with analytical models and simulation
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis shows the advantages of simple models for analysis of railway operation. It presents two tools for infrastructure and timetable planning. It shows how the infrastructure can be analysed through fictive line designs, how the timetable can be treated as a variable and how delays can be used as performance measures. The thesis also gives examples of analyses of complex traffic situations through simulation experiments.

Infrastructure configuration, timetable design and delays play important roles in the competitiveness of railway transportation. This is especially true on single-track lines where the run times and other timetable related parameters are severely restricted by crossings (train meetings). The first half of this thesis focuses on the crossing time, i.e. the time loss that occurs in crossing situations. A simplified analytical model, SAMFOST, has been developed to calculate the crossing time as a function of infrastructure configuration, vehicle properties, timetable and delays for two crossing trains. Three measures of timetable flexibility are proposed and they can be used to evaluate how infrastructure configuration, vehicle properties, punctuality etc affect possibilities to alter the timetable.

Double-track lines operated with mixed traffic show properties similar to those of single-tracks. In this case overtakings imply scheduled delays as well as risk of delay propagation. Two different methods are applied for analysis of double-tracks: a combinatorial, mathematical model (TVEM) and simulation experiments.

TVEM, Timetable Variant Evaluation Model, is a generic model that systematically generates and evaluates timetable variants. This method is especially useful for mixed traffic operation where the impact of the timetable is considerable. TVEM may also be used for evaluation of different infrastructure designs. Analyses performed in TVEM show that the impact on capacity from the infrastructure increases with speed differences and frequency of service for the passenger trains, whereas the impact of the timetable is strongest when the speed differences are low and/or the frequency of passenger services is low.

Simulation experiments were performed to take delays and perturbations into account. A simulation model was set up in the micro simulation tool RailSys and calibrated against real operational data. The calibrated model was used for multi-factor analysis through experiments where infrastructure, timetable and perturbation factors were varied according to an experimental design and evaluated through response surface methods. The additional delay was used as response variable. Timetable factors, such as frequency of high-speed services and freight train speed, turned out to be of great importance for the additional delay, whereas some of the perturbation factors, i.e. entry delays, only showed a minor impact. The infrastructure factor, distance between overtaking stations, showed complex relationships with several interactions, principally with timetable factors.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 53 p.
Series
Trita-TEC-PHD, ISSN 1653-4468 ; 10-001
Keyword
Railway operation, Railway capacity, Single-track, Double-track, Partial double-track, Inter-station distance, Delay, Delay propagation, Crossing, Overtaking, Timetable flexibility, Simulation, Experimental design
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-12727 (URN)978-91-85539-50-5 (ISBN)
Public defence
2010-05-28, E1, Lindstedtsvägen 3, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
Framtida infrastruktur och kvalitet i tågföring
Note
QC20100622Available from: 2010-05-12 Created: 2010-05-07 Last updated: 2010-06-22Bibliographically approved

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Citation style
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