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Simulation of rail traffic: applications with timetable construction and delay modelling
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.ORCID iD: 0000-0003-2023-0164
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis covers both applications where simulation is used on parts of the Swedish rail networks and running time calculations for future high-speed trains with top speed improvements on existing lines. Calculations are part of a subproject within the Green Train research program (Gröna tåget). Higher speeds are possible with increased cant and cant deficiency in curves. Data for circular curve radii is used on existing lines combined with information on decided and on-going upgrades. Calculation of static speed profiles is made for a set of cant and cant deficiency values. Different train characteristics are used regarding top speed, starting acceleration and power to ton ratio. Running time calculations are made for these different train characteristics with the fictive speed profiles. In addition, different stopping patterns are applied. Results are presented together with running times for two reference train types, one with carbody tilting and one without. It is clear that carbody tilting, allowing a higher cant deficiency, is important on many of the existing lines considering achieved running times. The benefit of tilting is marginal on newly built and future lines designed with large curve radii. However, on many of the existing lines the over 20 year old reference train with carbody tilting achieves shorter running times compared to a future train without tilt but with higher top speed. The work presented here has contributed with input to other projects and applications within the research program. Simulation in RailSys is used to evaluate on-time performance for high-speed trains, between Stockholm and Göteborg in Sweden, and changes in timetable allowances and buffer times with respect to other trains. Results show that ontime performance can be improved with increased allowances or buffer times. In the case with increased buffers, other trains are pushed in the timetable with the intention of obtaining at least five minutes at critical places (e.g. conflicting train paths at stations) and as separation on line sections. On-time performance is evaluated both on aggregated (group) level and for trains individually. Some of the trains benefit significantly from the applied measures. Prior to a simulation some of the delays have to be defined. This includes dwell extensions and entry delays, i.e. extended exchange times at stations and delayed origin station departures inside or at the network border. Evaluation of observed data give insight on the performance of a real network. However, separating primary (exogenous) and secondary (knock-on) delays is not straightforward. Typically the probabilities and levels of primary delays are defined as input, thus secondary delays are created in the simulations. Although some classification of delays exist in observed data, it is not sufficient without further assumptions and preparation. A method for estimating primary running time extensions is presented and applied on a real timetable between Katrineholm and Hässleholm in Sweden. The approach consist of creating distributions based on deviations from scheduled running time. Since this represent total outcome, i.e. both primary and knock-on delays are included, the distributions are reduced by a certain percentage and applied in the simulations. Reduction is done in four steps, separately for passenger and freight trains. Root mean square error (RMSE) is used for comparing mean and standard deviation values between simulated and observed data. Results show that a reasonably good fit can be obtained. Freight services show a higher variation than passenger train evaluation groups. Some explanations for this are difficulties in capturing the variations in train weights and speeds and absence of shunting operations in the model. In reality, freight trains can also frequently depart ahead of schedule and this effect is not captured in the simulations. However, focus is mostly on passenger trains and their on-time performance. If a good enough agreement and operational behaviour is achieved for them, a lower agreement for freight trains may be accepted.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , viii, 54 p.
Series
Trita-VNT
Series
Trita-TSC-LIC
National Category
Transport Systems and Logistics
Identifiers
URN: urn:nbn:se:kth:diva-97461ISBN: 978-91-85539-87-1 (print)OAI: oai:DiVA.org:kth-97461DiVA: diva2:533359
Presentation
2012-06-11, 10:15
Opponent
Supervisors
Note
QC 20120611Available from: 2012-06-13 Created: 2012-06-13 Last updated: 2012-06-13Bibliographically approved
List of papers
1. Körtidsberäkningar för Gröna tåget: Analys av tågkonfigurationer
Open this publication in new window or tab >>Körtidsberäkningar för Gröna tåget: Analys av tågkonfigurationer
2008 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2008. 71 p.
Series
KTH Järnvägsgruppen, 0802
National Category
Civil Engineering
Research subject
Järnvägsgruppen - Gröna tåget
Identifiers
urn:nbn:se:kth:diva-10777 (URN)978-91-7415-133-6 (ISBN)
Note

QC 20111114

Available from: 2009-07-21 Created: 2009-07-21 Last updated: 2015-07-16Bibliographically approved
2. Simulation of modified timetables for high speed trains Stockholm-Göteborg
Open this publication in new window or tab >>Simulation of modified timetables for high speed trains Stockholm-Göteborg
2010 (English)In: Road and Rail Infrastructure / [ed] Stjepan Lakušić, University of Zagreb , 2010Conference paper, Published paper (Refereed)
Abstract [en]

In this research project, involving KTH, Swedish Rail Administration and train operatingcompany SJ, timetable simulation is used on different areas in the Swedish railnetwork. The objective is to develop methods and strategies which can be usefulfor both long and short term timetable planning in the future.This study presents some of the result from simulations done on the Western mainin Sweden. Traffic is mixed with significant differences in average speeds. Thismakes the high speed passenger trains (X2000) sensitive for small delays and disturbancescaused by other, much slower trains.Simulation software RailSys was used to evaluate how increased and decreasedtime supplements for high speed trains affect punctuality. Also buffer times were increasedbetween X2000 and other trains. Delay distributions from previous projectswere implemented in order to model entry delays together with dwell and run timeextensions.Results show that increased buffer times can have a significant effect on punctuality.Some of the studied trains have a situation with dense traffic and high occurrenceof overtakings. This clearly increases average delays and contributes to a lowerpunctuality.

Place, publisher, year, edition, pages
University of Zagreb, 2010
Keyword
train traffic, timetable, simulation
National Category
Transport Systems and Logistics
Research subject
Transport Science
Identifiers
urn:nbn:se:kth:diva-76888 (URN)978-953-6272-38-9 (ISBN)
Conference
CETRA 2010 - First International Conference on Road and Rail Infrastructure. Opatija, Croatia. 17–18 May 2010
Note

TSC import 1068 2012-02-06. QC 20120425

Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2015-07-16Bibliographically approved
3. Calibration of Simulation Model on the Southern Main Line in Sweden
Open this publication in new window or tab >>Calibration of Simulation Model on the Southern Main Line in Sweden
2011 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Suitable analysis methods are needed for evaluation of future timetable scenarios, both in short term operational planning and for strategic planning with a longer time horizon. One method is to use simulation software which makes it possible to model large networks. The Swedish Transport Administration (Trafikverket) is in a process where the aim is to start using simulation software RailSys as a tool for timetable planning. This will at first be applied for long term strategic planning with the possibility to also use it in operational planning further on.

The main focus in this paper is to estimate primary run time extensions from registered data. Ideally these should only represent primary causes, e.g. decreased vehicle performance, variation in driver behaviour or infrastructure malfunctions. These extensions are important in order to make simulations more realistic.

Different reduction levels of registered data are tested in order to estimate primary run time extensions. Registered data used are absolute values without distinction between primary and secondary causes. Calibration simulations are done on the Southern main line in Sweden where the mix of high and low speed trains is substantial.

Keyword
railway operation, simulation, train delay
National Category
Transport Systems and Logistics
Research subject
Järnvägsgruppen - Kapacitet
Identifiers
urn:nbn:se:kth:diva-76754 (URN)
Conference
Railway Engineering 2011. London, UK. 28th June 2011 - 30th June 2011
Note

TSC import 863 2012-02-06. QC 20120413

Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2015-07-16Bibliographically approved

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