| 1. |
- Ait Ali, Abderrahman, 1991-, et al.
(författare)
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A disaggregate bundle method for train timetabling problems
- 2020
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- The train timetabling problem (TTP) consists of finding a feasible timetable for a number of trains which minimises some objective function, e.g., sum of running times or deviations from ideal departure times. One solution approach is to solve the dual problem of the TTP using so-called bundle methods. This paper presents a new bundle method that uses disaggregate data, as opposed to the standard bundle method which in a certain sense relies on aggregate data. We compare the disaggregate and aggregate methods on realistic train timetabling scenarios from the Iron Ore line in Northern Sweden. Numerical results indicate that the proposed disaggregate method reaches better solutions faster than the standard aggregate approach.
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| 2. |
- Andersson, Emma V., 1983-, et al.
(författare)
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Quantifying railway timetable robustness in critical points
- 2013
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Ingår i: Journal of Rail Transport Planning and Management. - : Elsevier. - 2210-9706 .- 2210-9714. ; 3:3, s. 95-110
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 3. |
- Boysen, Hans E.
(författare)
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Øresund and Fehmarnbelt high-capacity rail corridor standards updated
- 2014
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 4:3, s. 44-58
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Tidskriftsartikel (refereegranskat)abstract
- The Øresund and the planned Fehmarnbelt fixed links have recently adopted a set of standards that can significantly raise the operating efficiency and capacity of freight by rail. These standards are explained in the context of the German-Scandinavian railway corridor and in comparison to the European Technical Specifications for Interoperability. Using a quantitative model, the mass and volume load capacity per train are calculated. Compared to present constraining limitations in the German-Scandinavian corridor, the mass load capacity per train can be increased by 64%, and the volume load capacity by up to 220%.
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| 4. |
- Broman, Emanuel, et al.
(författare)
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Efficient capacity allocation on deregulated railway markets
- 2022
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier B.V.. - 2210-9706 .- 2210-9714. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- As railway markets are increasingly deregulated, coordinating and prioritising between capacity requests becomes more complex and more important. This paper describes the advantages and challenges of different allocation methods in vertically separated open-access railway markets, with several railway operators and heterogeneous traffic, and where a public infrastructure manager must resolve operators’ conflicting path requests. Three broad groups of allocation methods are described: administrative methods, allocation by social cost-benefit analysis and willingness-to-pay based allocation. We describe pros and cons of these allocation principles for three different market segments: commercial traffic with long planning horizons, (subsidized) traffic controlled by public transport agencies, and traffic with short planning horizons. We then outline an allocation process that meets the requirements of a deregulated market better than conventional methods. It is a mixed method, which uses an auction-like mechanism to allocate pre-defined paths to commercial operators on specified, capacity-constrained lines. The net social benefits of capacity reserved for traffic controlled by public transport agencies is assessed through social cost-benefit analysis of timetables. The benefits decrease when timetables are adjusted to make room for additional commercial train paths; the size of this loss determines the reservation price of the auction-like mechanism. Dynamic pricing is used for short-term allocation on congested line segments. © 2021
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| 5. |
- Forsgren, Malin, et al.
(författare)
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Maintaining tracks and traffic flow at the same time
- 2013
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 3:3, s. 111-123
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Tidskriftsartikel (refereegranskat)abstract
- In an ideal world, all railway tracks would be available to trains at all times. In reality, track sections need to be closed every now and again for track maintenance and upgrades in order to ensure a satisfactory level of safety and comfort. In this paper, we present a MIP model that optimizes a production plan with regard to both trains and preventive maintenance. The planned maintenance activities may not be canceled, but may be moved in time within pre-defined time windows. Trains may be moved in time, redirected to other parts of the geography, or even canceled. The goal for the optimization is to find the best possible traffic flow given a fixed set of planned maintenance activities. In addition to presenting the model, we discuss the current maintenance planning process in Sweden, and exemplify the usefulness of our model in practice by applying it to two typical scenarios.
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| 6. |
- Francisco, F., et al.
(författare)
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Is large technological investment really a solution for a major shift to rail? : A discussion based on a Mediterranean freight corridor case-study
- 2021
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to assess how the introduction of technological innovations into a capacity constrained rail corridor may increase its ability to capture market share from road transport. The Montpellier-Perpignan section, a bottle-neck in the Mediterranean corridor, is used as a case study for the effects of implementing new rolling stock that allows for freight trains up to 1500 m, a new ballastless track replacing existing one, resilient switches and crossings, and monitoring systems that allow for a reduction in maintenance costs and closure times. The results of a cost-benefit analysis show positive net impacts, however, the increases in capacity are only enough to maintain current rail freight market shares. Evidence suggests that a heavy investment in technology in existing lines is not the most effective way to increase rail market share.
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| 7. |
- Gestrelius, Sara, et al.
(författare)
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Timetable quality from the perspective of a railway infrastructure manager in a deregulated market : An interview study with Swedish practitioners
- 2020
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier B.V.. - 2210-9706 .- 2210-9714. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Railway capacity allocation in a deregulated market requires planners to solve a mathematically complex optimization problem while simultaneously arbitrating the wants and needs of different stakeholders. This paper analyses timetable quality from the perspective of timetable planners working for the Swedish infrastructure manager Trafikverket. Seven quality aspects are discussed: feasibility, disturbance resistance, competition management, capacity safeguarding, application fulfilment, attractiveness and compatibility with surrounding planning areas. Each aspect is introduced, including references to legal documents, development projects, and research literature. Further, an interview study with eight practitioners gives insight into the current state of practice in Sweden. The practitioners consider feasibility to be both most important and easiest to handle. Capacity safeguarding is considered least important, despite its prevalence in legal documents and envisioned process developments, and is also considered hardest to handle. In general, formal rules and guidelines seem important for emphasising the importance of a quality aspect in the planning process. To better support the planners in their arbitrating role, timetable planning tools based on mathematical optimization models could be implemented. For example, support tools could be used to analyse different solutions, and could unburden the planner from working with feasibility aspects by providing automatic conflict identification and resolution.
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| 8. |
- Gestrelius, Sara, et al.
(författare)
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Towards a comprehensive model for track allocation and roll-time scheduling at marshalling yards
- 2017
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 7:3, s. 157-170
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers multi-stage train formation with mixed usage tracks at a marshalling yard without departure yard. A novel integer programming model for scheduling shunting tasks as well as allocating arrival yard tracks and classification bowl tracks is presented. By taking a comprehensive view of the marshalling yard operations, more effective schedules can be found, and a variety of characteristics can be optimised, including shunting work effort, number or cost of tracks, and shunting task start times. Two different objective functions are evaluated: minimising work effort in terms of wagon pull-backs and minimising track costs. A procedure for finding a hot-start solution with few wagon pull-backs is also presented. The proposed model is tested on real data from Sävenäs marshalling yard in Sweden. The results show that the method is able to return an optimal schedule for a planning period of 4 days if the hot-start solution is optimal or the remaining problem is tractable for the heuristics in CPLEX.
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| 9. |
- Hultkrantz, Lars, 1952-
(författare)
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A note on high-speed rail investments and travelers`value of time
- 2013
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 3:1-2, s. 14-21
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Tidskriftsartikel (refereegranskat)abstract
- High-speed rail (HSR) is designed for travellers with high value of time. HSR offers fast and reliable services and good possibilities for work during the journey. Surprisingly, these benefits of HSR investments are often appraised with travel-time value of people who use conventional train services. This note considers under what circumstances the assumption that the value of time remains unchanged by the speed improvement induces a significant bias in appraisals. We first outline some conceptual points with a modal-mix model where travellers have varying value of time and then discuss how this could affect the social profitability of three recently constructed or proposed HSR lines: Oslo–Stockholm (Norway and Sweden), Stockholm–Goteborg (Sweden) and Beijing–Shanghai Hongqiao (China). We conclude that economic evaluations of HSR line should at the least be complemented by a sensitivity analysis of the possible effect of a change of the composition of travellers with various values of travel time.
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| 10. |
- Joborn, Martin, et al.
(författare)
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Understanding causes of unpunctual trains : Delay contribution and critical disturbances
- 2022
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier B.V.. - 2210-9706 .- 2210-9714. ; 23
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we define new concepts and metrics for improved understanding of causes to unpunctual trains. The metrics are denoted delay contribution and critical disturbance. Delay contribution can be interpreted as how much a specific disturbance contributes to the delay of a train and the critical disturbances can be interpreted as the disturbances that made the train become unpunctual. The metrics are applied in a test case with trains in southern Sweden. The results show that the metrics can provide a complementary view regarding causes to unpunctuality compared to standard methods and are able to pinpoint disturbances that made trains become unpunctual and separate them from disturbances that have less impact on the punctuality. The methods are useable in the continuous work to improve railway performance e.g., by prioritizing maintenance work that give best impact on punctuality. © 2022 The Authors
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