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Andersson, Emma
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Publications (6 of 6) Show all publications
Andersson, E., Peterson, A. & Törnquist Krasemann, J. (2015). Improved Railway Timetable Robustness for Reduced Traffic Delays – a MILP approach. In: 6th International Conference on Railway Operations Modelling and Analysis, Tokyo, Mars 23-26, 2015.: . Paper presented at 6th International Conference on Railway Operations Modelling and Analysis - RailTokyo.
Open this publication in new window or tab >>Improved Railway Timetable Robustness for Reduced Traffic Delays – a MILP approach
2015 (English)In: 6th International Conference on Railway Operations Modelling and Analysis, Tokyo, Mars 23-26, 2015., 2015Conference paper, Published paper (Refereed)
Abstract [en]

Maintaining high on-time performance and at the same time having high capacity utilization is a challenge for several railway traffic systems. The system becomes sensitive to disturbances and delays are easily propagating in the network. One way to handle this problem is to create more robust timetables; timetables that can absorb delays and prevent them from propagating. This paper presents an optimization approach to reduce the propagating of delays with a more efficient margin allocation in the timetable. A Mixed Integer Linear Programming (MILP) model is proposed in which the existing margin time is re-allocated to increase the robustness for an existing timetable. The model re-allocates both runtime margin time and headway margin time to increase the robustness at specific delay sensitive points in a timetable. We illustrate the model’s applicability for a real-world case where an initial, feasible timetable is modified to create new timetables with increased robustness. These new timetables are then evaluated and compared to the initial timetable. We evaluate how the MILP approach affects the initial timetable structure and its capability to handle disturbances by exposing the initial and the modified timetables to some minor initial disturbances of the range 1 up to 7 minutes. The results show that it is possible to reduce the delays by re-allocating margin time, for example, the total delay at end station decreases with 28 % in our real-world example.

Keywords
Railway traffic, Timetabling, Robustness, Margin re-allocation, Punctuality, Optimization
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-116651 (URN)
Conference
6th International Conference on Railway Operations Modelling and Analysis - RailTokyo
Projects
Robusta tidtabeller för järnvägstrafik
Available from: 2015-03-30 Created: 2015-03-30 Last updated: 2018-08-23Bibliographically approved
Andersson, E. (2014). An Economic Evaluation of the Swedish Prioritisation Rule for Conflict Resolution in Train Traffic Management. In: Procedia - Social and Behavioral Sciences: Transportation: Can we do more with less resources?. Paper presented at 16th Meeting of the Euro Working Group on Transportation, 4-6 September 2013, Porto, Portugal (pp. 634-644). Elsevier
Open this publication in new window or tab >>An Economic Evaluation of the Swedish Prioritisation Rule for Conflict Resolution in Train Traffic Management
2014 (English)In: Procedia - Social and Behavioral Sciences: Transportation: Can we do more with less resources?, Elsevier, 2014, p. 634-644Conference paper, Published paper (Refereed)
Abstract [en]

An increase in train traffic is a politically welcomed trend, which on the other hand has led to too high capacity utilisation at times and a railway network sensitive to disturbances. Delays are easily spread, causing high cost. A mean of controlling the secondary delays is to use efficient operational prioritisation rules for trains in conflict. This paper presents an evaluation of the current Swedish prioritisation rule. For two frequent conflict situations the associated cost related to applying the rule is calculated. The result indicates a poor economic efficiency and show that significant savings can be achieved by changing strategy.

Place, publisher, year, edition, pages
Elsevier, 2014
Series
Procedia - Social and Behavioral Sciences, ISSN 1877-0428 ; 111
Keywords
Railway traffic, delay management, operational planning, prioritising, delay costs
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-104675 (URN)10.1016/j.sbspro.2014.01.097 (DOI)000335582500065 ()
Conference
16th Meeting of the Euro Working Group on Transportation, 4-6 September 2013, Porto, Portugal
Available from: 2014-02-21 Created: 2014-02-21 Last updated: 2014-11-03Bibliographically approved
Andersson, E. V. (2014). Assessment of Robustness in Railway Traffic Timetables. (Licentiate dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Assessment of Robustness in Railway Traffic Timetables
2014 (English)Licentiate thesis, monograph (Other academic)
Abstract [en]

A tendency seen for the last decades in many European railway networks is a growing demand for capacity. An increased number of operating trains has led to a delay sensitive system where it is hard to recover from delays, where even relatively small delays are easily propagating to other traffic.

The overall aim of this thesis is to analyse the robustness of railway traffic timetables; why delays are propagating in the network and how the timetable design and dispatching strategies influence the delays. In this context we want to establish quantitative measures of timetable robustness. There is a need for measures that can be used by the timetable constructors. Measures that identify where and how to improve the robustness and thereby indicating how and where margin time should be inserted. It is also important that the measures can capture interdependencies between different trains.

In this thesis we introduce the concept of critical points, which is a practical approach to identify robustness weaknesses in a timetable. In contrast to other measures, critical points can be used to identify specific locations in both time and space. The corresponding measure, Robustness in Critical Points (RCP) provides the timetable constructors with concrete suggestions for which trains that should be given more runtime or headway margin. The measure also identifies where the margin time should be allocated to achieve a higher robustness.

In a case study we show that the delay propagation is highly related to the operational train dispatching. This study shows that the current prioritisation rule used in Sweden results in an economic inefficiency and therefore should be revised. This statement is further supported by RCP and the importance of giving the train dispatchers more flexibility to efficiently solve conflict situations.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. p. 99
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1636
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-103676 (URN)10.3384/lic.diva-103676 (DOI)LIU-TEK-LIC-2013:70 (Local ID)978-91-7519-437-0 (ISBN)LIU-TEK-LIC-2013:70 (Archive number)LIU-TEK-LIC-2013:70 (OAI)
Presentation
2014-01-31, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2014-01-22 Created: 2014-01-22 Last updated: 2018-08-23Bibliographically approved
Andersson, E., Peterson, A. & Törnquist Krasemann, J. (2013). Introducing a New Quantitative Measure of Railway Timetable Robustness Based on Critical Points. In: 5th International Seminar on Railway Operations Modelling and Analysis - RailCopenhagen 2013: . Paper presented at 5th International Seminar on Railway Operations Modelling and Analysis, Copenhagen, May 13-15, 2013.
Open this publication in new window or tab >>Introducing a New Quantitative Measure of Railway Timetable Robustness Based on Critical Points
2013 (English)In: 5th International Seminar on Railway Operations Modelling and Analysis - RailCopenhagen 2013, 2013Conference paper, Published paper (Refereed)
Abstract [en]

The growing demand for railway capacity has led to high capacity consumption at times and a delay-sensitive network with insufficient robustness. The fundamental challenge is therefore to decide how to increase the robustness. To do so there is a need for accurate measures that return whether the timetable is robust or not and indicate where improvements should be made. Previously presented measures are useful when comparing different timetable candidates with respect to robustness, but less useful to decide where and how robustness should be inserted. In this paper, we focus on points where trains enter a line, or where trains are being overtaken, since we have observed that these points are critical for the robustness. The concept of critical points can be used in the practical timetabling process to identify weaknesses in a timetable and to provide suggestions for improvements. In order to quantitatively assess how crucial a critical point may be, we have defined the measure RCP (Robustness in Critical Points). A high RCP value is preferred, and it reflects a situation at which train dispatchers will have higher prospects of handling a conflict effectively. The number of critical points, the location pattern and the RCP values constitute an absolute value for the robustness of a certain train slot, as well as of a complete timetable. The concept of critical points and RCP can be seen as a contribution to the already defined robustness measures which combined can be used as guidelines for timetable constructors.

Keywords
Timetabling, robustness measures, railway traffic
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-92712 (URN)978-87-7327-246-6 (ISBN)
Conference
5th International Seminar on Railway Operations Modelling and Analysis, Copenhagen, May 13-15, 2013
Available from: 2013-05-16 Created: 2013-05-16 Last updated: 2018-08-23
Andersson, E. V., Peterson, A. & Törnquist Krasemann, J. (2013). Quantifying railway timetable robustness in critical points. Journal of Rail Transport Planning & Management, 3(3), 95-110
Open this publication in new window or tab >>Quantifying railway timetable robustness in critical points
2013 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 3, no 3, p. 95-110Article in journal (Refereed) Published
Abstract [en]

Several European railway traffic networks experience high capacity consumption during large parts of the day resulting in delay-sensitive traffic system with insufficient robustness. One fundamental challenge is therefore to assess the robustness and find strategies to decrease the sensitivity to disruptions. Accurate robustness measures are needed to determine if a timetable is sufficiently robust and suggest where improvements should be made.

Existing robustness measures are useful when comparing different timetables with respect to robustness. They are, however, not as useful for suggesting precisely where and how robustness should be increased. In this paper, we propose a new robustness measure that incorporates the concept of critical points. This concept can be used in the practical timetabling process to find weaknesses in a timetable and to provide suggestions for improvements. In order to quantitatively assess how crucial a critical point may be, we have defined the measure Robustness in Critical Points (RCP). In this paper, we present results from an experimental study where a benchmark of several measures as well as RCP has been done. The results demonstrate the relevance of the concept of critical points and RCP, and how it contributes to the set of already defined robustness measures.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Delay management; Railway traffic; Robustness measures; Timetabling
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-106703 (URN)10.1016/j.jrtpm.2013.12.002 (DOI)
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2018-08-23Bibliographically approved
Andersson, E., Peterson, A. & Törnquist Krasemann, J. (2011). Robustness in Swedish Railway Traffic Timetables. In: S. Ricci, I.A. Hansen, G. Longo, D. Pacciarelli, J. Rodriguez, E. Wendler (Ed.), Railrome 2011: Book of Abstracts 4th International Seminar on Railway Operations Modelling and Analysis. Paper presented at 4th International Seminar on Railway Operations Modelling and Analysis, Sapienza - University of Rome,February 16-18, 2011.
Open this publication in new window or tab >>Robustness in Swedish Railway Traffic Timetables
2011 (English)In: Railrome 2011: Book of Abstracts 4th International Seminar on Railway Operations Modelling and Analysis / [ed] S. Ricci, I.A. Hansen, G. Longo, D. Pacciarelli, J. Rodriguez, E. Wendler, 2011Conference paper, Published paper (Other academic)
Abstract [en]

A tendency seen for quite some time in the Swedish railway network is a growing demand for capacity which no longer can be accommodated. This causes congestion and delays, and the relationships between the trains and how they affect eachother are significantly harder to overview and analyse. Railway traffic timetables normally contain margins to make them robust, and enable trains to recover from certain delays. How effective these margins are, depends on their size and location as well as the frequency and magnitude of the disturbances that occur. Hence, it is important to include marigns so, that they can be used operationally to recover from a variety of disturbances and not restricted to a specific part of the line and/or the timetable. In a case study we compare the performance of a selection of passenger train services to the different prerequisites given by the timetable (e.g. available margins and their location, critical train dependencies). The study focuses on the Swedish Southern mainline between Stockholm and Malmö on which a wide variety of train services operate, e.g. freight trains, local and regional commuter train services as well as long-distance trains with different speed profiles. The analysis shows a clear mismatch between where margins are placed and where delays occur. We also believe that the most widely used performance measure, which is related to the delay when arriving at the final destination, might give rise to an unnecessarily high delay rate at intermediate stations.

Keywords
Railway traffic, Scheduling, Robustness, Delay management.
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:liu:diva-79257 (URN)
Conference
4th International Seminar on Railway Operations Modelling and Analysis, Sapienza - University of Rome,February 16-18, 2011
Available from: 2012-07-05 Created: 2012-07-04 Last updated: 2018-08-23Bibliographically approved
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