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Investigating The Impact Of Timetable Properties On Delay Propagation On A Double-Track Line Using Extensive Simulation
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.ORCID iD: 0000-0002-5192-8074
2011 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Today many railway lines are operated close to maximum capacity. A common question asked is: “How is the quality of operation affected if one additional train/h is scheduled?” With the upcoming deregulation of operation, the necessity to be able to answer this question accurately increases when service operators that are denied train slots due to congestion demand a motivation.

The objective of this paper is to investigate how secondary delays on a congested double-track line depend on several parameters such as:

  • Number of trains/h.

  • Timetable heterogeneity (speed difference).

  • Primary delay levels.

  • Inter-station distance.

Each combination of settings of the parameters is investigated to capture possible interaction effects.

The infrastructure model consists of a fictitious double-track line with overtaking stations at regular intervals. A program that generates timetables and perturbation data according to specified input settings is developed. The output of the program is data files that can be read directly by the well-known simulation tool RailSys. This process makes it possible to simulate the hundreds of different timetables that are the result when the parameters investigated are varied. The outcome of the simulations is analysed to find the influence of the investigated parameters on the secondary delays.

Place, publisher, year, edition, pages
2011.
Keyword [en]
Train delay, railway operation, double-track, simulation, heterogeneity
National Category
Transport Systems and Logistics
Research subject
Järnvägsgruppen - Kapacitet
Identifiers
URN: urn:nbn:se:kth:diva-76752OAI: oai:DiVA.org:kth-76752DiVA: diva2:491125
Conference
Railway Engineering. London, UK. 29th June 2011 - 30th June 2011
Note

QC 20120330

Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2015-09-02Bibliographically approved
In thesis
1. Congested railways: influence of infrastructure and timetable properties on delay propagation
Open this publication in new window or tab >>Congested railways: influence of infrastructure and timetable properties on delay propagation
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis the symptoms and underlying behaviour of congestion on railways are analysed and discussed. As well as in many other countries, Sweden faces increasing demand for transport. To meet this new demand, railways play an important role. Today, the capacity of the Swedish rail network is not upgraded at the speed necessary to keep up with the increase in traffic demand. The sensitivity of the railway system rises as the capacity utilisation increases. At some point the marginal gain of operating one extra train is lower than the costs in term of increased sensitivity to delay, i.e. maximum capacity has been reached.

Two methodologies are employed in this thesis to analyse capacity. The first uses real data from the Swedish rail network, train operation and delays to analyse how different factors influence available capacity and delay creation. Several useful key performance indicators are defined to describe capacity influencing properties of the infrastructure and the rail traffic. The rail network is divided into subsections for which the indicators have been estimated. This makes it possible to discern their different characteristics and identify potential weaknesses.

 The second approach employs the railway simulation tool RailSys in extensive simulation experiments. This methodology is used to analyse the characteristics of double track operation. Simulation of several hundred scenarios are conducted to analyse the influence of traffic density, timetable speed heterogeneity, primary delays and inter-station distance on secondary delays and used timetable allowance. The analysis gives an in-depth understanding of the mechanisms behind the performance of a double track.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 44 p.
Series
Trita-TSC-LIC, 12-005
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-97569 (URN)978-91-85539-90-1 (ISBN)
Presentation
2012-06-11, V2, KTH, Teknikringen 76, Stockholm, 14:15
Opponent
Supervisors
Note
QC 20120614Available from: 2012-06-14 Created: 2012-06-14 Last updated: 2012-06-14Bibliographically approved
2. Railway capacity analysis: Methods for simulation and evaluation of timetables, delays and infrastructure
Open this publication in new window or tab >>Railway capacity analysis: Methods for simulation and evaluation of timetables, delays and infrastructure
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis the symptoms and underlying behaviour of congestion on railways are analysed and discussed. As well as in many other countries, Sweden faces increasing demand for transportation. To meet this new demand, railways play an important role. Today, the capacity of the Swedish rail network is not upgraded at the pace necessary to keep up with the increase in traffic demand. The sensitivity of the railway system rises as the capacity utilisation increases. At some point maximum capacity is reached when the marginal gain of operating one extra train is lower than the costs in terms of longer travel times and increased sensitivity to delays.

Several different methodologies are employed in this thesis to analyse capacity. The first uses real data from the Swedish rail network, train operation and delays to analyse how different factors influence available capacity and train delays. Several useful key performance indicators are defined to describe capacity influencing properties of the infrastructure and the rail traffic. The rail network is divided into subsections for which the indicators have been estimated. This makes it possible to discern their different characteristics and identify potential weaknesses.

The second approach employs the railway simulation tool RailSys in extensive simulation experiments. This methodology is used to analyse the characteristics of double-track operation. Simulation of several hundred scenarios are conducted to analyse the influence of traffic density, traffic heterogeneity, primary delays and inter-station distance on secondary delays, used timetable allowance and capacity. The analysis gives an in-depth understanding of the mechanisms of railway operation on double-track lines.

A simulation model for strategic capacity evaluation, TigerSim, is developed that can be used to speed up and improve capacity planning and evaluation of future infrastructure and timetables designs on double-track railway lines. For a given infrastructure and plan of operation, the model can be used to generate and simulate a larger number of timetables. This gives two major advantages:

  • Using many timetables makes results general
  • It is possible to consider both static and dynamic properties of the timetables in the capacity analysis

The first aspect is especially useful in the evaluation of future scenarios as the timetable then often is unknown. The second is an advantage since an improvement in capacity can be measured in a combination of increased frequency of service, shorter travel time and reduced delays. The output of the model can either be used to directly determine capacity from a quality of service perspective, or used as input to cost-benefit analysis (CBA).

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. x, 67 p.
Series
TRITA-TSC-PHD, 15:002
National Category
Transport Systems and Logistics
Research subject
Järnvägsgruppen - Kapacitet
Identifiers
urn:nbn:se:kth:diva-172916 (URN)978-91-87353-65-9 (ISBN)
Public defence
2015-09-22, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150902

Available from: 2015-09-02 Created: 2015-09-01 Last updated: 2015-09-02Bibliographically approved

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Lindfeldt, Anders

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