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Validation of a simulation model for capacity evaluation of double-track railway lines
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering. (Järnvägsgruppen)ORCID iD: 0000-0002-5192-8074
2015 (English)In: Proceedings of the 6th International Seminar on Railway Operations Modelling and Analysis (RailTokyo2015), Tokyo, Japan, 2015Conference paper (Refereed)
Abstract [en]

Capacity is partially a matter of quality versus quantity. Increasing capacity utilization gives more scheduled waiting time in the timetable as well as more delays when trains are operated. A common way to analyse capacity is to first make a timetable and then use it in a simulation where trains are perturbed. This way it is possible to establish the scheduled waiting time and the expected delays of the trains at the same time as market demands on traffic, e.g. frequency of different train services, are considered. However, setting up simulations are often time consuming and requires a lot of input data.

A method is developed with the objective to improve and speed up capacity analysis of double track railway lines. It can be used for both timetable generation and timetable simulation. The focus of this paper is to present the model and validate that it can simulate timetables accurately. The model has a macroscopic representation of the railway infrastructure and rolling stock while timetables and perturbations are modelled in more detail. When resolving conflicts, the dispatching algorithm can consider several trains and take into account how the dispatching decision affects the possibility to make good decisions at the next station.

The validation is performed using the micro simulation tool RailSys as reference. The validation covers a wide range of scenarios of different traffic density, timetable heterogeneity, inter station distance and primary delays. The validation shows good results and the conclusion is that despite the simplicity of the model, it is accurate enough to use in capacity analysis.

Place, publisher, year, edition, pages
Keyword [en]
Railway, simulation, validation, delay, capacity
National Category
Transport Systems and Logistics
URN: urn:nbn:se:kth:diva-170870OAI: diva2:840752
RailTokyo 2015,March 23-26, 2015, Tokyo

Qc 20150716

Available from: 2015-07-09 Created: 2015-07-09 Last updated: 2015-09-02Bibliographically approved
In thesis
1. 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.
National Category
Transport Systems and Logistics
Research subject
Järnvägsgruppen - Kapacitet
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)

QC 20150902

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

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