| 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. |
- Ait Ali, Abderrahman, 1991-
(författare)
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Methods for Capacity Allocation in Deregulated Railway Markets
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Faced with increasing challenges, railways around Europe have recently undergone major reforms aiming to improve the efficiency and competitiveness of the railway sector. New market structures such as vertical separation, deregulation and open access can allow for reduced public expenditures, increased market competition, and more efficient railway systems.However, these structures have introduced new challenges for managing infrastructure and operations. Railway capacity allocation, previously internally performed within monopolistic national companies, are now conferred to an infrastructure manager. The manager is responsible for transparent and efficient allocation of available capacity to the different (often competing) licensed railway undertakings.This thesis aims at developing a number of methods that can help allocate capacity in a deregulated (vertically separated) railway market. It focuses on efficiency in terms of social welfare, and transparency in terms of clarity and fairness. The work is concerned with successive allocation of capacity for publicly controlled and commercial traffic within a segmented railway market.The contributions include cost benefit analysis methods that allow public transport authorities to assess the social welfare of their traffic, and create efficient schedules. The thesis also describes a market-based transparent capacity allocation where infrastructure managers price commercial train paths to solve capacity conflicts with publicly controlled traffic. Additionally, solution methods are developed to help estimate passenger demand, which is a necessary input both for resolving conflicts, and for creating efficient timetables.Future capacity allocation in deregulated markets may include solution methods from this thesis. However, further experimentations are still required to address concerns such as data, legislation and acceptability. Moreover, future works can include prototyping and pilot projects on the proposed solutions, and investigating legal and digitalisation strategies to facilitate the implementation of such solutions.
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| 3. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Värdering av trafikinformationsnyttor i tågtrafiken (VTT) : slutrapport
- 2024
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tågförseningar tillsammans med ökande efterfrågan leder till betydande sociala kostnader. Ett sätt att minska dessa kostnader är genom effektiv kommunikation av olika typer av trafikinformation till passagerare. Beroende på vilken/när information tas emot minskar passagerarnas beteendeanpassningar deras resekostnader, särskilt vid förseningar.Detta projekt syftar till att beräkna de samhällsekonomiska nyttor som sådan trafikinformation ger. Detta åstadkoms genom att utveckla en kvantitativ modell för att kvantifiera värdet av att kommunicera information till resenärerna vid tågförseningar.Genom att studera olika störningsscenarier i ett studiefall från Stockholmspendeltåg, ger studien insikter till infrastrukturförvaltaren om samhällsnytta av sådana informationssystem som en del av de stora infrastrukturinvesteringarna. Dessa insikter kan också hjälpa till att utforma effektivare informationsstrategier för att minska samhällsekonomiska kostnader för tågstörningar.
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| 4. |
- Andersson, Emma, 1983-, et al.
(författare)
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Increasing robustness at single-track lines using the indicator robustness in passing pointss
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When several trains are planned to use the same infrastructure resource, there is always a risk for spreading of delays, which can be hard to recover from. It is a challenge for the Infrastructure Manager to make timetables that accommodate as much traffic as possible, without causing bad on-time performance. Timetable planners are in need of quantitative indicators to assess timetable robustness and accurate methods for how to make the timetable more robust.In this paper we assess the robustness for single-track lines with non-periodic timetables. At single-track lines, trains use the line for running in both directions and the trains can only pass or overtake each other at passing loops. This makes the system more sensitive for delays. In this paper we present a robustness indicator which captures the dependencies between trains at a single-track line. The indicator can be used to illustrate weaknesses in a timetable and also to indicate where and how to insert more robustness. In a simulation study, we show that it is possible to improve the performance by making small timetable adjustments according the indicator, without increasing runtimes or capacity utilization.
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| 5. |
- 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
-
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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| 6. |
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| 7. |
- Fowler, Scott, et al.
(författare)
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An Empirical Evaluation of Web System Access for Smartphone Clients
- 2012
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Ingår i: Journal of Networks. - : Academy Publisher. - 1796-2056. ; 7:11, s. 1700-1713
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Tidskriftsartikel (refereegranskat)abstract
- As smartphone clients are restricted in computational power and bandwidth, it is important to minimise the overhead of transmitted messages. This paper identifies and studies methods that reduce the amount of data being transferred via wireless links between a web service client and a web service. Measurements were performed in a real environment based on a web service prototype providing public transport information for the city of Hamburg in Germany, using actual wireless links with a mobile smartphone device. REST based web services using the data exchange formats JSON, XML and Fast Infoset were evaluated against the existing SOAP based web service.
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| 8. |
- Gestrelius, Sara, et al.
(författare)
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A MILP-based heuristic for a commercial train timetabling problem
- 2017
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Ingår i: Transp. Res. Procedia. - : Elsevier BV. ; , s. 569-576, s. 569-576
-
Konferensbidrag (refereegranskat)abstract
- Using mathematical methods to support the yearly timetable planning process has many advantages. Unfortunately, the train timetabling problem for large geographical areas and many trains is intractable for optimization models alone. In this paper, we therefore present a MILP-based heuristic that has been designed to generate good-enough timetables for large geographical areas and many trains. In the incremental fix and release heuristic (IFRH), trains are added to the timetable in batches. For each batch of trains, a reduced timetable problem is solved using a mathematical integer program and CPLEX. Based on the solution, the binary variables defining meeting locations and stops are fixed, and the next batch of trains is added to the timetable. If previously fixed variables make the problem infeasible, a recovery algorithm iteratively releases fixed variables to regain feasibility. The paper also introduces a simple improvement heuristic (IH) that uses the same idea of working with batches of trains. The heuristics are tested on a real case-study from Sweden consisting of both small problem instances (approximately 300 trains and 1400 possible interactions) and large problem instances (approximately 600 trains and 5500 possible interactions). IFRH returns a feasible timetable within 30 minutes for all problem instances, and after running IH the optimality gaps are less than 5%. Meanwhile, if CPLEX is used without the heuristic framework to solve the total optimization problem, a feasible timetable is not returned within 2 hours for the large problem instances. © 2017 The Authors.
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| 9. |
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| 10. |
- Gestrelius, Sara, 1986-
(författare)
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Optimisation models for train timetabling and marshalling yard planning
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Railways provide high capacity, safe and energy efficient transportation of goods and passengers. However, railway transportation also suffers from intrinsic restrictions and the effectiveness and efficiency of the transportation depend on the railway actors’ ability to solve a set of hard and interconnected planning problems. As the digitalisation of rail-way planning advance, compute-intensive decision support tools could be implemented to support the planners’ work. Two support functions that would be useful are automatic generation of new plans and optimisation of existing plans. In this thesis, mathematical models are developed and analysed for optimisation of (1) train timetables and (2) marshalling yard plans. The aim is to investigate the feasibility and potential of using mixed integer linear programming (MILP) models to solve these two planning problems. To this aim, requirements and planning goals are identified and modelled as mathematical constraints and objective functions. The resulting mathematical models are then tested on realistic problem instances, and the execution times and optimised plans are analysed to determine if the mathematical models could be useful in practice.The thesis contributes with an analysis of the definition of ”good” in a railway timetable setting from the perspective of an infrastructure manager, a novel mathematical model for timetable planning, an optimisation-based heuristic for decreasing execution times and last but not least an analysis of the potential of using optimisation to enable a new type of annual capacity allocation. For marshalling yard planning, the thesis contributes with an analysis of three different mathematical models for planning one of the sub-yards of a marshalling yard, and with an extended, more comprehensive, mathematical model that can be used to plan two sub-yards. Further, a heuristic is developed for the more comprehensive problem, and the effects of optimising two sub-yards rather than one are analysed.The overall conclusion is that MILP models can contribute to improved railway planning. By using MILP optimisation, more effective plans can be made faster. However, more research is needed to reach the full potential of mathematical optimisation for railway planning problems, in particular when it comes to user experience and user interaction, but also to further decrease the execution times and extend the problem scope that can be handled.This thesis consists of two parts. The first part introduces and summarises the research. It provides background knowledge on the two planning problems as well as on mathematical optimisation, and also present the research framework and some overall conclusions and suggestions for future work. The second part of the thesis consists of five appended papers, three on train timetabling and two on marshalling yard planning.
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| 11. |
- Gestrelius, Sara, 1986-, et al.
(författare)
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Tidtabellskvalitet (TTK) : Teknisk Slutrapport
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- KAJT projektet TTK (Tidtabellskvalitet) var ett treårigt projekt som syftade till att ta fram ett ramverk som mäter en tidtabells kvalitet. Effektmålet är bättre balanserade och därmed mer kvalitativa tidtabeller.I den här slutrapporten presenteras de resultat som togs fram under projektet. Det är dels texter baserade på litteraturstudier (kapitel 5 och delar av kapitel 7), ochs dels rapportering av resultat från workshoppar, en intervjustudie (kapitel 6) och den första implementation av ramverket (kapitel 7).Projektet undersökte kvalitetsmått för fem kvalitetsaspekter: teoretisk körbarhet, robusthet och återställningsförmåga, konkurrenshantering, reservkapacitet och ansökningsuppfyllnad. Fyra slutsatser från projektet är att:I dagens process finns det skrivna regler för teoretisk körbarhet, robusthet och tvistlösning. Övriga kvalitetsaspekter saknas det tydliga regler för, och det saknas helt stöd för att kunna väga olika kvalitetsaspekter mot varandra.Det saknas forskning på kvalitetsmått för vissa kvalitetsaspekter. När det kommer till trafik så saknas specifikt publicerade mått för reservkapacitet och konkurrenshantering, trots att dessa aspekter lyfts fram i både svensk och europeisk lagstiftning. För att kunna designa ett fullvärdigt ramverk för flermålsoptimering krävs kvalitetsmått även för dessa aspekter.I dagens planeringsprocess bedöms aspekterna teoretisk körbarhet och robusthet som viktiga. Minst viktig bedöms reservkapacitet vara. Däremot upplevs reservkapacitet som absolut svårast att jobba med.Ramverket som projektet tog fram har testats på Värmlandsbanan. Kvalitetsmätningar genomfördes för andra torsdagen i oktober för 2014-2018. I dess mätningar syns en förbättring för ett flertal mått mellan 2016 och 2017 års tidtabeller, vilket är förväntat då nya konstruktionsregler infördes 2017. Ramverket med flermålsoptimering testades på andra torsdagen i oktober 2018. Tre styrpunkter användes för att ta fram tre olika tidtabeller, varav ingen dominerar de andra. Resultatet visar att det, i alla fall i enskilda trafikdagar, finns utrymme för att generera olika pareto-optimala tidtabeller. Det vill säga, givet att man inte i förväg kan bestämma sig för vilka kvalitetsmått som är viktigast, så kan man generera ett antal tidtabeller där ingen är absolut bättre än de andra.Viktiga framtida forskningsområden är (1) att identifiera och implementera mätvärden för banarbeten i kvalitetsramverket, (2) att ta fram kvalitetsmått för de aspekter där sådana saknas, (3) att ta fram metoder för att säkerställa att tåglägen som går över flera konstruktionsområden är av god kvalitet (4) att ta fram en metod för att hantera gapet mellan teori och praktik samt (5) att undersöka olika kvalitetsmåtts effektivitet.Vidare rekommenderar vi att Trafikverket undersöker möjligheterna för att ta fram riktlinjer även för de kvalitetsaspekter som inte är teoretisk körbarhet och robusthet, samt utvecklar processer och stödverktyg som hjälper tidtabellsplanerare väga olika kvalitetsaspekter mot varandra.
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| 12. |
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| 13. |
- Johansson, Ingrid, 1990-, et al.
(författare)
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Rail platform allocation for reliable interchanges
- 2024
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Ingår i: Transportation Research Procedia. - : Elsevier BV. - 2352-1465. ; 78, s. 198-205, s. 198-205
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Tidskriftsartikel (refereegranskat)abstract
- Changing trains is a crucial part of many rail journeys, and it is important that arrival and departing trains are allocated close to each other for a swift interchange. Today the platform allocation of trains is often based on local traditions, where trains of the same type to the same destination depart from the same track. In this paper we address the problem of using the platform tracks in the best way, balancing crossing train paths with easy interchanges at the same platform. We use a RailSys model of the station in Norrköping, Sweden, to assess three platform allocation strategies with respect to crossing train paths and train changes at the same platform. Moreover, the capacity utilisation is calculated by a timetable compression-based method. The results show that a platform allocation maximising the changes at the same platform leads to more crossing train paths and higher capacity utilisation. Future work includes more accurate modelling of train connections, assessment of delays through simulation, and a cost-benefit analysis to find the best balance between easy interchanges and conflicting train paths.
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| 14. |
- Licciardello, Riccardo, et al.
(författare)
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Integrating yards, network and optimisation models towards real-time rail freight yard operations
- 2020
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Ingår i: Ingegneria Ferroviaria. - Rome, Italy : Collegio Ingegneri Ferroviari Italiani. - 0020-0956. ; 6, s. 417-440
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the state of advancement achieved in the OptiYard research project in the use of optimisation algorithms in interaction with microsimulation of the rail-yard and surrounding network towards realtime yard management and communication with the network. Two case studies, a hump marshalling yard (mainly Single Wagon Load traffic) and a flat shunting yard (mainly intermodal traffic), were represented with state-of-the art microsimulation models, combined with innovative optimisation algorithms. Some specialistic information on the nature of the models is provided. However, the focus is oriented to railway engineers, with a description of the interactions between the models in producing outputs that are useful both to the yard dispatcher (decisions on staff, track, locomotive assignment, order of operations) and the infrastructure manager of the surrounding network (expected times of departure, availability of tracks in the yard).
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| 15. |
- Lindberg, Therese, et al.
(författare)
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A Simulation Model of Local Public Transport Access at a Railway Station
- 2017
-
Ingår i: Proceedings of Raillille 2017 - 7th lnternational Conference on Railway Operations Modelling and Analysis. - 9782857827238 ; , s. 922-943
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A high quality railway service requires that all parts of the complete journey, from door to door, are well-functioning. This includes any transfers taking place, as well as last mile transportation to and from the railway station. Since the last mile often consists of local public transport, the access to this mode at stops and terminals and how well these are functioning are of great importance. A critical aspect is the capacity of the stop or the terminal in relation to the number of departures, where a higher capacity generally means an increase in size. At the same time it is desirable to limit the use of valuable land and keeping the facility as small as possible. The trade-off between capacity and size needs to be evaluated when designing stops and terminals.In this study we have developed a discrete event simulation model of a combined bus and tram stop, which is a part of a larger multi-modal station. The objective of the study is to evaluate the modelling approach for the situation at hand. Of special interest are the complexities due to the different driving patterns of buses and trams. The developed model is capable of evaluating design alternatives and is applied in a case study of a stop at Norrköping railway station in southern Sweden. The model was found to realistically capture the various events occurring at such a stop and the case study further showed that the model is a useful tool in design evaluation.
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| 16. |
- Lindberg, Therese, 1986-, et al.
(författare)
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An integer optimization model for allocation of bus lines to the stops of a bus terminal
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Interchange stations are essential for a high-quality public transport system. Many passengers pass through a station during the course of a day and the time spent at a station has a large effect on their experience of the whole journey. In this study, we aim to improve the passenger experience at a bus terminal by minimizing the walking distances for all passengers. To this end, an integer linear optimization model which allocates bus lines to the stops of a bus terminal is presented. The model is tested in a numerical experiment using synthetic passenger data. Two alternative approaches, either randomly allocated or based on the number of non-transferring passengers, are used for comparisons. The average improvement in relation to the random allocation strategy is 13%, which shows that the allocation approach has potential. It is thus of interest to collect data from a real bus terminal to further explore the model and the potential benefits it can provide.
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| 17. |
- Lindberg, Therese, 1986-
(författare)
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Discrete Event Simulation of Bus Terminals
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Public transport is important to society as it provides spatial accessibility and reduces congestion and pollution in comparison to other motorized modes. To assure a high-quality service, all parts of the system need to be well-functioning and properly planned. One important aspect for the system's bus terminals is their capacity. This needs to be high enough to avoid congestion and queues and the delays these may lead to. During planning processes, various suggested designs and solutions for a terminal need to be evaluated. Estimating capacity and how well the suggestions will function is a challenging problem, however. It requires analysis of complex interactions and behaviour of the vehicles. This sort of analyses can preferably be carried out using microsimulation. Furthermore, a discrete event simulation approach can make use of the fact that the path of a vehicle through a terminal can readily be described by a sequence of events (such as arriving, starting to drive to a stop etc.).The overall aim of this thesis is to investigate how discrete event simulation can be used to evaluate bus terminal design and traffic control policies. The main contribution is the development of a method for bus terminal simulation. As a first step, a discrete event simulation model of a combined bus and tram stop is formulated. The model is tested on a real system where the current design is compared to an alternative one. The test shows that a model developed with a discrete event approach can be used to evaluate the situation at a stop and compare design alternatives. In the next step, a general discrete event simulation model of bus terminals is formulated. A modular approach is introduced, where a terminal can be constructed from a set of module building blocks. Another important contribution of the model is its spatial resolution that allows for queues and blockages to occur throughout the terminal. By applying the simulation model in a case study, it is shown that the model can be used to evaluate and compare various scenarios related to the layout, number of passengers and the outside traffic situation. Lastly, the bus terminal simulation model is used in a second case study in order to compare model output with empirical data. This study identified a number of factors that may have had an influence on differences between observations and simulation results and that is of interest to look further into. This includes the actual adherence to terminal rules and the effects of model parameters.
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| 18. |
- Ljunggren, Fredrik, et al.
(författare)
-
Maximum Robust Train Path for an Additional Train Inserted in an Existing Railway Timetable
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra's algorithm.We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph.
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| 19. |
- Ljunggren, Fredrik, et al.
(författare)
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Railway timetabling : a maximum bottleneck path algorithm for finding an additional train path
- 2021
-
Ingår i: Public Transport. - : Springer. - 1866-749X .- 1613-7159. ; 13, s. 597-623
-
Tidskriftsartikel (refereegranskat)abstract
- We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness, that is, a train path that maximizes the temporal distance to neighboring trains in the timetable. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra’s algorithm. We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph.
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| 20. |
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| 21. |
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| 22. |
- Peterson, Anders, Docent, 1976-
(författare)
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Deliverable 32.2 : Capacity impacts of innovations
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Deliverable D32.2 “Capacity impacts of innovations” summarizes the results of the Capacity 4 Rail work package WP3.2 “Simulation and models to evaluate enhanced capacity (infrastructure and operation)”. Capacity in the railway system can be divided in strategic level (planning of infrastructure), tactical level (timetabling) and operational level (dispatching). Closely related to the operational planning are Driver Advisory Systems (DAS), which in the future may be extended towards fully automatized driving.At strategic level an analysis have been made about line capacity and train capacity for future rail freight corridors. The analysis shows how to increase capacity for future freight trains 2030/2050, by extending the train capacity well as the line capacity and the combination of train and line capacity for futures scenarios.In the future, the processes for tactical and operational planning are merging, meaning that the timetable is no longer a static, or annually updated, product, but a working document that is improved successively, until handed over to operational management. Also in the operational management, we believe that control by planning is a good strategy. Processes for capacity and timetable planning, as well as timetable and traffic simulation systems are under development. The amount of available data is increasing.The main research results of Capaciyt 4Rail SP 3.2 have been:1. A model framework for modelling and planning of demand and supply of capacity at various levels with micro simulation, data analysis and optimisation. By combining these methods especially tactical and operational planning and control can be improved, and hence, enabling more trains and/or increased on-time performance.2. A statistical model (LiU model) to forecast delay propagation. The model relies on the theory of Bayesian networks, and can be used both for planning and informing.3. A demonstrator, CAIN, an extension to the KADR system for timetable and operational traffic developed by Oltis group Czech. The CAIN tool is connected to the LiU model and relies on data from Railsys (micro level infrastructure, complete tracklayout modelled) and Trafikverket database of disturbances and delays Lupp. The demonstrator has been set-up for Malmö – Hallsberg, a part of the Scandinavian Mediterranean corridor TEN-T network. It has given us new knowledge about interaction between IM timetable system and optimisation/data analysis model to predict timetable robustness and punctuality in the network due to changes in the timetable.4. A separate analysis of space–time points in the timetable critical for robustness. The study of critical points in this project has given knowledge about how to use the method when data is known at micro level, represented by RailSys. The improved robustness is also set in relation to other key performance indicators.
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| 23. |
- Peterson, Anders, Docent, 1976-, et al.
(författare)
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Deliverable D 3.1: Analysis of the gap between daily timetable and operational traffic
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fr8Rail II/Work-Package 3 Real-time network management and improved methods for timetable planning addresses the problem to improve capacity and punctuality in the railway system by developing concepts and methods for tactical planning and operational traffic. In this report the state-of-the-art has been summarised.The aim of the project is to:Propose concepts and methods that improve the annual and short-term timetable planning.Demonstrate how the proposed timetable planning concepts improve the prerequisites for real-time network management.Develop methods and tools that can reduce inefficiencies in real time network management.An important aspect is to improve the coordination between yards/terminals and the line network, and between Infrastructure Manager, Yard Managers, and freight Rail Undertakings.We motivate our research by the current situation in Sweden, which is characterised by low on-time performance for freight trains, dense and heterogenous traffic on the major railway lines, and a rigid annual timetabling process, which is non-suitable for short-term changes. We believe that better tools for network planning and management on tactical and operational level can help to connect planning and operational processes.Aiming for improvements of the operational traffic, there is a need for systematic development of methods applied at several planning horizons, based on both simulation and optimization techniques. Close to operation fast methods are needed, for example, based on meta-heuristics.The maintenance planning process and improvement potential have been described. This is a new piece of the puzzle and it is important to close the gap between timetable planning and operational traffic. The different planning processes at the Infrastructure Manager, the Rail Undertakings and the Maintenance Contractors should be aligned.When developing new approaches for computational decision-support tools for real-time network management, it is important — but very challenging — to evaluate and benchmark with existing software tools. We also observe that the research stream on computational decision-support and algorithm development for railway traffic management has not yet been sufficiently merged with the corresponding research stream focusing on aspects of human computer interaction.
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| 24. |
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| 25. |
- Peterson, Anders, 1976-
(författare)
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Origin-destination matrix estimation from traffic counts
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For most kind of analyses in the field of traffic modeling, there is a need for origin-destination (OD) matrices, which specify the travel demands between the origin and destination nodes in the network. The process of obtaining OD-matrices is long, complicated and expensive. The counting of traffic, which provides link flow observations, therefore is an opportune possibility for easily up-dating the information on the travel demand. This thesis concerns the estimation of OD-matrices from traffic counts. We will consider the problem to estimate OD-matrices for both time-indepenent and time-dependent models. Many models have been suggested for the time-independent case, where the quantities represent and average situation. If a user equilibrium is assumed for the link flows in the network, a bilevel problem structure is recognized, where the link flows are implicitly expressed as a traffic assignment of the present OD-matrix. A descent heuristic, which is an adaptation of the well-known projected gradient method, is proposed. Special attention is given to the problem of approximating the Jacobian matrix, which expresses the change of a certain link flow with respect to a unit change of the travel demand in a certain pair of origin and destination.When a time dimension is introduced, the estimation problem becomes more complex. Besides the problem of distributing the travel demand onto different routes, the flow propagation with respect to time must be handled. A general time-dependent extension of the estimation problem is given and the complications with dynamic traffic assignment are discussed. In a case study, the conventional solution technique is improved by introducing pre-adjustment schemes, which the structure of the information provided by the OD-matrix and the link flow observations.
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| 26. |
- Peterson, Anders, 1976-
(författare)
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The Origin-Destination Matrix Estimation Problem : Analysis and Computations
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For most kind of analyses in the field of traffic planning, there is a need for origin--destination (OD) matrices, which specify the travel demands between the origin and destination nodes in the network. This thesis concerns the OD-matrix estimation problem, that is, the calculation of OD-matrices using observed link flows. Both time-independent and time-dependent models are considered, and we also study the placement of link flow detectors.Many methods have been suggested for OD-matrix estimation in time-independent models, which describe an average traffic situation. We assume a user equilibrium to hold for the link flows in the network and recognize a bilevel structure of the estimation problem. A descent heuristic is proposed, in which special attention is given to the issue of calculating the change of a link flow with respect to a change of the travel demand in a certain pair of origin and destination nodes.When a time-dimension is considered, the estimation problem becomes more complex. Besides the problem of distributing the travel demand onto routes, the flow propagation in time and space must also be handled. The time-dependent OD-matrix estimation problem is the subject for two studies. The first is a case study, where the conventional estimation technique is improved through introducing pre-adjustment schemes, which exploit the structure of the information contained in the OD-matrix and the link flow observations. In the second study, an algorithm for time-independent estimation is extended to the time-dependent case and tested for a network from Stockholm, Sweden.Finally, we study the underlying problem of finding those links where traffic flow observations are to be performed, in order to ensure the best possible quality of the estimated OD-matrix. There are different ways of quantifying a common goal to cover as much traffic as possible, and we create an experimental framework in which they can be evaluated. Presupposing that consistent flow observations from all the links in the network yields the best estimate of the OD-matrix, the lack of observations from some links results in a relaxation of the estimation problem, and a poorer estimate. We formulate the problem to place link flow detectors as to achieve the least relaxation with a limited number of detectors.
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| 27. |
- Peterson, Anders, 1976-
(författare)
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Towards a robust traffic timetable for the Swedish Southern Mainline
- 2012
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Ingår i: Computers in Railways XIII. - Ashurst : WIT Press. - 9781845646165 ; , s. 473-484
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We identify the on-time performance as a key to evaluate a railway timetable’s robustness to disturbances and evaluate the on-time performance for two single services on the Swedish Southern Mainline for the autumn period 2011. We analyse the punctuality by studying how the performance develops en route. Typically the time spent in the stations is underestimated, which partly is compensated for by time margins along the line, giving rise to a sawtooth formed delay muster with an increasing trend. The standard deviation in the delay reports seems to be a good indicator for the precision in the traffic. In this material it is almost linearly increasing with a good minute per hour scheduled running time. Two attempts are made to change the timetable for a better performance. By using socio-economic values a customer-oriented description of the current timetable is calculated as a trade-off between high punctuality and short travel time. This timetable does not affect any other traffic. Minor effects to other traffic would be the result if the existing margins are re-distributed to better match the demand en route in some sense. As long as no more time supplement is added, we will, however, not improve on the punctuality to the final destination. For future research is left, how the decrease in precision can be accounted for already in the timetable construction.
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| 28. |
- Solinen, Emma, et al.
(författare)
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A microscopic evaluation of railway timetable robustness and critical points
- 2017
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier. - 2210-9706 .- 2210-9714. ; 7:4, s. 207-223
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Tidskriftsartikel (refereegranskat)abstract
- One method to increase the quality of railway traffic flow is to construct a more robust timetable in which trains are able both to recover from delays and the delays are prevented from propagating. Previous research results show that the indicator Robustness in Critical Points (RCP) can be used to increase timetable robustness. In this paper we present the use of a method for RCP optimization: how it can be assessed ex-post via microscopic simulation. From the evaluation we learn more about how increased RCP values influence a timetable's performance. The aim is to understand more about RCP increase at a localised level within a timetable in terms of effects to the pairs of trains that are part of the indicator. We present a case study where an initial timetable and a timetable with increased RCP values are evaluated. The ex-post evaluation includes the quantification of measures concerning train-borne delay and robustness of operations, as well as measures capturing the subsequent quality of service experienced by passengers to assess the broader effects of improved robustness. The result shows that it is necessary to use several key performance indicators (KPIs) to evaluate the effects of an RCP increase. The robustness increases at a localised level, but the results also indicate that there is a need to analyse the relationship between ex-post measures and RCP further, to improve the method used to increase RCP and thus its overall effect on timetable robustness.
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| 29. |
- Solinen, Emma, 1983-, et al.
(författare)
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A Microscopic Evaluation of Robustness in Critical Points
- 2017
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Ingår i: 7th International Conference on RailwayOperations Modelling and Analysis (RailLille 2017). - : International Association of Railway Operations Research. ; , s. 83-103
-
Konferensbidrag (refereegranskat)abstract
- One method to increase the quality of railway traffic flow is to construct a more robust timetable in which trains are able to both recover from delays and the delays are prevented from propagating. Previous research results show that the indicator Robustness in Critical Points (RCP) can be used to increase timetable robustness. In this paper we present the use of a method for RCP optimization, how can be implemented and assessed ex-post via microscopic simulation and subsequently evaluated. From the evaluation we learn more about how increased RCP values influence a timetable’s performance. The aim is to understand more about RCP increase at a localised level within a timetable in terms of effects to the pairs of trains that are part of the indicator. We present a case study where an initial timetable and a timetable with increased RCP values are evaluated. The ex-post evaluation includes the quantification of measures concerning train-borne delay and robustness of traffic flow, as well as measures capturing the subsequent quality of service experienced by passengers to assess the broader effects of improved robustness. The result shows that it is necessary to use several Key Performance Indicators (KPIs) to evaluate the effects of an RCP increase. The robustness will increase at a localised level, but the results also indicate that there is a need to analyse the relationship between ex-post measures and RCP further, to improve the method used to increase RCP and thus its overall effect on timetable robustness.
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| 30. |
- Wahlborg, Magnus, et al.
(författare)
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D3.1 – Final pre-study for an improved methodology for timetable planning including state-of-the-art and future work plan
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In ARCC project work package 3, research and innovation activities have been done to identify areas with a need for improved timetable planning methods and outline how new methods can be developed and implemented.Improved timetable planning scope were described and there was an activity to connect to other relevant Shift2Rail projects. An workshop was organised in Stockholm 2018-05-29.State of the art in practice was described for timetable planning in Sweden, UIC 406 method and Ansaldo STS Traffic management systems. Also state of the art in algorithms was described.Future work plan research needs areas are:1. Understanding of various goals for timetabling and how they co-variate2. Residual capacity3. Connection and coordination of the planning processes4. Connection and coordination of the yard/terminal planning and network planning5. Integration of freight trains into the timetable, focusing on short-term and ad-hoc6. Integration of maintenance scheduling and timetabling, at all planning stages7. Improved decision support for handeling of deviations from timetable in operations8. Features of planning tools, and implementation of automatized timetabling
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| 31. |
- Yu, Liyun, et al.
(författare)
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A MILP Model for Rescheduling Freight Trains under an Unexpected Marshalling-Yard Closure
- 2023
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Ingår i: Book of Abstracts. - : The Faculty of Transport and Traffic Engineering, University of Belgrade, Serbia. - 9788673954677 ; , s. 68-68
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study is about rescheduling freight trains to reduce the eff ects of major interruptions. In this paper, we consider that the interruption is an unexpected marshallingyard closure. We develop a macroscopic Mixed-Integer Linear Programming (MILP)model to reschedule railway timetables. One important principle is that we simultaneously reschedule several trains, instead of one-by-one. Furthermore, we consider arescheduling strategy of letting trains wait on the way when the destination yard havea closure. The model considers stopping restrictions and the capacity of each segmentand station. The order of the trains aff ected by the interruption is not fi xed. We presentexperimental results of three diff erent cases, which are all based on artifi cial data.
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