| 1. |
- Arasteh khouy, Iman, et al.
(författare)
-
Cost-effective track geometry maintenance limits
- 2016
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 230:2, s. 611-622
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Tidskriftsartikel (refereegranskat)abstract
- In the past, railway maintenance actions were usually planned based on the knowledge and experience of the infrastructure owner. The main goal was to provide a high level of safety, and there was little concern about economic and operational optimisation issues. Today, however, a deregulated competitive environment and budget limitations are forcing railway infrastructures to move from safety limits to cost-effective maintenance limits to optimise operation and maintenance procedures. By so doing, one widens the discussion to include both operational safety and cost-effectiveness for the whole railway transport system. In this study, a cost model is proposed to specify the cost-effective maintenance limits for track geometry maintenance. The proposed model considers the degradation rates of different track sections and takes into account the costs associated with inspection, tamping, delay time penalties, and risk of accidents due to poor track quality. It draws on track geometry data from the Iron Ore Line (Malmbanan) in northern Sweden, used by both passenger and freight trains, to estimate the geometrical degradation rate of each section. The methodology is based on reliability and cost analysis and facilitates the maintenance decision-making process to identify cost-effective maintenance thresholds.
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| 2. |
- Arasteh khouy, Iman, et al.
(författare)
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Evaluation of track geometry degradation in swedish heavy haul railroad - A case study
- 2012
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Ingår i: International Journal of COMADEM. - 1363-7681. ; 15:2, s. 11-16
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Tidskriftsartikel (refereegranskat)abstract
- The measurement and improvement of track quality are key issues in determining both the time and cost of railway maintenance. Efficient track geometry maintenance ensures optimum allocation of limited maintenance resources and has an enormous effect on maintenance efficiency. Applying the appropriate tamping strategy also helps reduce maintenance costs, making operations more cost effective and leading to increased safety and passenger comfort. In this paper, track geometry data from the iron ore line in northern Sweden, which handles both passenger and freight trains, are used to calculate track quality degradation trend in a cold climate. The paper describes Trafikverket’s (Swedish Transport Administration) tamping strategy and illustrates the distribution of safety failures in different seasons. It also analyses the track geometry degradation and discuss about the possible reasons for distribution of failures over a year and along the track.
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| 3. |
- Arasteh Khouy, Iman, et al.
(författare)
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Evaluation of track geometry maintenance for a heavy haul railroad in Sweden: A case study
- 2014
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 228:5, s. 496-503
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Tidskriftsartikel (refereegranskat)abstract
- The measurement and improvement of track quality are key issues in determining both the restoration time and cost of railway maintenance. Applying the optimal tamping strategy helps reduce maintenance costs, making operations more cost effective and leading to increased safety and passenger comfort. In this paper, track geometry data from the iron ore line (Malmbanan) in northern Sweden, which handles both passenger and freight trains, are used to evaluate track geometry maintenance in cold climate. The paper describes Trafikverket’s (Swedish Transport Administration) tamping strategy and evaluates its effectiveness in measuring, reporting, and improving track quality. Finally, it evaluates the performance of the maintenance contractor and discusses the importance of the functional requirements stated in the outsourcing contracts.
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| 4. |
- Arasteh khouy, Iman, et al.
(författare)
-
Geometrical degradation of railway turnouts : a case study from a Swedish heavy haul railroad
- 2014
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 228:6, s. 611-619
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Tidskriftsartikel (refereegranskat)abstract
- Turnouts are critical components of track systems in terms of safety, operation and maintenance. Each year, a considerable part of the maintenance budget is spent on their inspection, maintenance and renewal. Applying a cost-effective maintenance strategy helps to achieve the best performance at the lowest possible cost. In Sweden, the geometry of turnouts is inspected at predefined time intervals using the STRIX / IMV 100 track measurement car. This study uses time series for the measured longitudinal level of turnouts on the Iron Ore Line (Malmbanan) in northern Sweden. Two different approaches are applied to analyse the geometrical degradation of turnouts due to dynamic forces generated by train traffic. In the first approach, the recorded measurements are adjusted at the crossing point and then the relative geometrical degradation of turnouts is evaluated by using two defined parameters, the absolute residual area and the maximum settlement, In the second approach, various geometry parameters are defined to estimate the degradation in each measurement separately. The growth rate of the longitudinal level degradation as a function of million gross tonnes / time is evaluated. The proposed methods are based on characterisation of the individual track measurements. The results facilitate correct decision-making in the maintenance process through understanding the degradation rate and defining the optimal maintenance thresholds for the planning process. In the long run, this can lead to a cost-effective maintenance strategy with optimised inspection and maintenance intervals.
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| 5. |
- Arasteh khouy, Iman, et al.
(författare)
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Geometrical degradation of switches and crossings on a Swedish heavy haul railroad : a case study
- 2013
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Ingår i: Proceedings of 10th International Heavy Haul Association Conference. - New Delhi, India. - 9788192651903 ; , s. 26-32
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Konferensbidrag (refereegranskat)abstract
- Switches and crossings (S&Cs) are one of the most critical components of railway track systems in terms of safety, operation and maintenance. Each year, a considerable part of the maintenance budget is spent on inspection, maintenance and renewal of S&Cs. However, applying a cost-effective maintenance strategy helps to achieve the best performance at the lowest possible cost. In Sweden, the geometry of S&Cs is inspected at pre-defined time intervals by the STRIX track measurement car. In this paper, time series for the measured longitudinal level of S&Cs on the Iron Ore Line (Malmbanan) in northern Sweden have been used. Two parameters have been defined in this study, namely the absolute residual area (ARa) and the maximum settlement (Smax), to analyse the geometrical degradation of switches and crossings due to dynamic forces generated from train traffic. The paper also evaluates the growth rate of the longitudinal level degradation as a function of million gross tonnes (MGT). The results facilitate correct decision making in the maintenance process through understanding the degradation rate and defining the optimal maintenance thresholds for the planning process. In the long run this will lead to a cost-effective maintenance strategy with optimized inspection and maintenance intervals.
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| 6. |
- Arasteh khouy, Iman, et al.
(författare)
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Optimisation of track geometry inspection interval
- 2014
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 228:5, s. 546-556
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Tidskriftsartikel (refereegranskat)abstract
- The measurement and improvement of track quality are key issues in determining the time at which railway maintenance must be performed and its cost. Efficient track maintenance ensures optimum allocation of limited maintenance resources which has an enormous effect on maintenance efficiency. Applying an appropriate tamping strategy helps reduce maintenance costs, making operations more cost-effective and leading to increased safety and passenger comfort levels. This paper discusses optimisation of the track geometry inspection interval with a view to minimising the total ballast maintenance costs per unit traffic load. The proposed model considers inspection time, the maintenance-planning horizon time after inspection and takes into account the costs associated with inspection, tamping and risk of accidents due to poor track quality. It draws on track geometry data from the iron ore line (Malmbanan) in northern Sweden, used by both passenger and freight trains, to find the probability distribution of geometry faults.
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| 7. |
- Ardeberg, Arne, et al.
(författare)
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On the history of star formation in the bar of the Large Magellanic Cloud
- 1997
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Ingår i: ASTRONOMY AND ASTROPHYSICS. - : SPRINGER VERLAG. - 0004-6361. ; 322:2, s. L13-L16
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Tidskriftsartikel (refereegranskat)abstract
- With the HST PC and uvby photometry, we investigate evolutionary signatures in a field in the centre of the LMC Bar. Field stars close to the turn off point in the HR diagram are used for a study of ages and evolution of the stellar popu lations dominatin
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| 8. |
- Asplund, Matthias, et al.
(författare)
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Inspection of railway turnouts using camera
- 2013
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Konferensbidrag (refereegranskat)abstract
- The railway turnout is an essential component in a railway system, used to divert traffic along different tracks. A turnout includes a number of different parts, including the switch blade, frog, point machine, switch roller, soleplate, check rail, wing rail, drive rods, control rods and other bars. These parts must be kept in good condition, meeting functional and safety requirements. Failing to comply will result in a reduction of the network’s capacity with economic consequences. Not honouring the safety limits could result in severe accidents, including derailment, causing human casualties. By performing the right type of inspection and/or maintenance at the right time, these unwanted events can be reduced. To determine if and when a maintenance action should be performed, the condition of the turnout must be established, usually by manual inspections or with measurement vehicles. The drawback is the discrete nature of these inspection events. Failure modes with development times shorter than the inspection interval could result in a malfunction of the unit. An on-line measurement system would be able to deal with these failure events and initiate correct maintenance actions at an earlier stage. With an on-line system, remotely located turnouts could be inspected without on-site personnel. Capacity consuming failures of turnouts with a strategic location or with bottleneck characteristics could also be corrected before they affect traffic. This paper describes a feasibility study of a camera based inspection system for turnouts and discusses the effect the method could have on system reliability and capacity.
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| 9. |
- Ekberg, Anders, 1967, et al.
(författare)
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INNOTRACK Deliverable 4.2.3 -- Improved model for loading and subsequent deterioration of insulated joints
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Numerical simulations have been carried out to assess the influence of key parameters on the deterioration of insulated joints. The measures of fatigue damage were adopted; one low-cycle fatigue based and one ratcheting based. Both of these models are based on the stress–strain evolution, which consequently needs to be accurately modelled. This calls for a constitutive model that can deal with plasticity under general multi- axial loading. In the current study the material parameters in the constitutive model have been calibrated to reflect the characteristics of the rail steel grade 900A.The simulations verify previous findings that the insulating layer does not carry any significant load. Consequently severe strains occur at the rail head edge. The ratcheting based fatigue criterion was found to be the most suitable for the current study and the accumulated plastic strain after four load passages, εeff, was adopted to quantify the ratcheting. The numerical simulations showed that increasing the insulating gap from 4 mm to 6 mm gives roughly the same effect as an increase of the vertical load from 150 kN to 200 kN, which is an increase in εeff of about 10%. In addition, a very detrimental effect of traction and braking was found: Increasing the longitudinal load from 0 kN up to 45 kN caused an increase in εeff magnitudes with up to 95%.The predictions of plastic deformation and rolling contact fatigue have been performed. A fixed traction coefficient was presumed giving a wear pattern that is a linear function of pressure, which is in turn proportional to the cube-root of the applied normal force. The highest wear is predicted immediately after the insulated joint, with additional high-wear spots appearing a few metres later as the wheel bounces down and settles.In addition to numerical simulations four operational joints have been monitored in field to follow the degradation. It was found that material damage is induced very fast. In accordance to numerical simulations the rail ends closest to a nearby station showed the largest degree of damage. This damage had a wear-like appearance. After 8 months it was found that also “cavity-like” damages had formed in the vicinity of the insulating joint.
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| 10. |
- Espling, Ulla, et al.
(författare)
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Strategi och metodutveckling av underhållsgränser för fordon och bana : optimering av fordons- och banunderhåll sett ur ett ekonomiskt perspektiv
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Både spårägare och trafikföretag ser en allt större ekonomiskt vinst att i att gå över från förutbestämt (tids- eller kilometerbaserat) till tillståndsbaserat underhåll. Vid denna övergång är det viktigt att se över både metoder för tillståndsbedömning och gränsvärden för underhåll och utifrån dessa välja en underhållstrategi som blir kostnadseffektivt för hela järnvägstransportsystemet. Genom att diskutera underhållsgränser istället för säkerhetsgränser lyfts fokus till att omfatta både driftsäkerhet och kostnadseffektivitet för hela järnvägstransportsystemet. Med underhållsgränser avses en avvägning av underhållsinsatser kontra ekonomi i syfte att uppnå estimerad livslängd och leverera efterfrågad funktion till rätt pris. Syftet är att effektivisera underhållet, öka livslängden genom att minska antal hjul- och rälsbyten per år, samt att få en klarare återkoppling av underhållsåtgärder - effekt - till rätt kostnad och rätt pris. En förstudie har genomförts i syfte att utreda användandet av underhållsgränser bland järnvägsförvaltare i världen. Den mynnade ut i ett förslag till en pilotstudie som sedan genomförts med Malmbanan som "laboratorium" och med stöd av TTCI (Transport Technology Center, Inc). Projektet har uppnått synergieffekter genom att resurser lånats från andra pågående forskningsprojekt vid JVTC. Dessa är DeCoTrack-spårnedbrytning och fordonsklassning, Tillståndsbaserat underhåll för malmvagnar, LCC för spårväxlar, Utvecklingsprojekt TURSAM/SAMPLA och JVTC Forskningsstationen i Sävast. Målet är att finnas en metodologi och ett arbetssätt som gör det möjligt att finna tillämpbara kostnadseffektiva gränsvärden för underhåll av fordon och bana i samverkan. Pilotstudien inkluderar både en kartläggning av de system som används idag, en genomgång av möjlig teknik att utveckla för framtiden (resultat från forskningsstationen), litteratursökning (inte uppfinna hjulet på nytt), insamling av empirisk data och samlade erfarenheter från underhållspersonal samt en fallstudie i syfte att kartlägga vad man kan göra idag, brister och förbättringsområden. Resultat visare att för flera av de tillståndsmätningar som utförs idag finns redan underhållsgränser införda, t.ex.: Spårlägesmätningarnas B-fel Hjulskadedetektorns varningsnivå För att få en mer komplett bedömning av banan behövs förutom de metoder som finns idag även: Metod för att maskinellt detektera ytskador på räler Detaljerade uppgifter om spårväxlar Uppföljning av skarvar, svetsarFör att få en mer komplett bedömning av fordon behövs förutom de metoder som finns idag även: Mätning av lateralkrafter och gångegenskaper Tidig detektion av lagerskador Hjulprofil Eventuellt test av bromsar Bättre kvalité på detektering av ytdefekter Den dokumentation som behövs för att följa upp nedbrytningen är idag inte komplett och brister på så sätt att endast generella slutsatser kan dras. Viktiga förbättringar är: Alla underhållsåtgärder som påverkar anläggningen, oberoende om de genomförs efter en besiktning, revision eller ett akut fel, dokumenteras i ett system BIS uppdateras för varje förändring i anläggningen, vilket åligger entreprenören Åtgärder som inte är relaterade till objekt ska positionsbestämmas med spårkm-angivelse(stations- och sträckinformation är för grovt). I fall av okulär besiktning måste skadetyperna specificeras enligt kod, ev. bör man kräva att tillståndskontrollanter har certifierad kunskap om rälsskador Statistik över vilka fordon som passerat, tonnage, antal axlar och spårkrafter. Identifikation av fordonstyp och axel Data från forskningsstation kan användas för fordonsklassificering och bör kunna kopplas ihop med nedbrytningen på räl. Omvänt måste också hypoteser listas för när banan förorsakar hjulnedbrytning, t.ex. när friktionen ökar. Minst lika viktigt är att utveckla informationshanteringen från alla typer av detektorer, vilket kräver automatiska identifikation av de vagnar som man önskar följa. Med vagns ID är det möjligt att delge tågoperatörer och infrastrukturägare data som kan användas för trendning och fastställande av lämpliga underhållsgränser. Utifrån information som insamlas om en bandel kan man fastställa vilka underhållsgränser som tillämpas idag. Detta utgör då grunden för att förändra dessa gränser på ett sådant sätt att både trafikutövare och banförvaltare minskar sina kostnader. Litteraturstudierna visar att tillräckligt med kunskap finns för att påbörja ett sådant arbete. Däremot saknas heltäckande underlag för att säkert kunna säga om åtgärder ger effekt på kort sikt eftersom den historik som idag finns inte är av tillräckligt bra kvalitet. På längre sikt (3 år) är detta inget problem eftersom ett driftsäkerhetstänkande också innebär att även kvalitén på underhållsdata ska säkerställas. Det fortsatta arbetet bör inriktas mot: att ringa in de kostnadsdrivare som finns för fordon och bana. Att kartlägga samband mellan specifika hjul- och fordonsskador och räldefekter. Verifiering av effekter från underhållsåtgärder, t.ex. genom att mäta spårkrafterna i asymmetrisk slipade kurvor. En kartläggning av vilka nedbrytningsmodeller/simuleringsmodeller som kan komma till användning för prediktering av underhållsinsatser Koppling mot ekonomi, dvs. beräkning av hur stor påverkan av kostnadsdrivare blir genom att förändra underhållsstrategin.
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| 11. |
- Famurewa, Stephen Mayowa, et al.
(författare)
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Augmented utilisation of possession time : Analysis for track geometry maintenance
- 2016
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 230:4, s. 1118-1130
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Tidskriftsartikel (refereegranskat)abstract
- The demand for increased capacity on existing railway networks is a challenge for many Europe-based infrastructure managers; addressing this challenge requires augmented utilisation of track possession time. It is considered that large-scale maintenance tasks such as geometry maintenance can be improved; thus, reducing the on-track maintenance time and allowing more traffic. In this study, an analysis of track geometry maintenance was performed with the objective of reducing the required possession time. The procedure and models for planning and optimizing track geometry maintenance are presented. A statistical model that uses a simulation approach was used to determine the condition of the track geometry, and a schedule optimization problem was formulated to support intervention decisions and optimize the track possession time. The results of the case study show that optimizing the maintenance shift length and cycle length are opportunities to reduce the extent of track possession required for the maintenance of the track geometry. In addition, continuous improvement of the tamping process through lean analysis promises about a 45% reduction in the required possession time for a tamping cycle.
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| 12. |
- Famurewa, Stephen Mayowa, et al.
(författare)
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Scheduling of Railway Infrastructure Maintenance Tasks Using Train Free Windows
- 2016
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Ingår i: Current Trends in Reliability, Availability, Maintainability and Safety. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319235967 - 9783319235974 ; , s. 425-436
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Konferensbidrag (refereegranskat)abstract
- Condition based maintenance scheduling is a promising approach towards effective track possession management in railway transport. If the maintenance tasks arising from condition monitoring and inspection of railways are efficiently scheduled, high service quality and capacity would be assured. In this paper, the authors presents a short-term maintenance scheduling problem to efficiently use available train-free periods for restoration of potential failures such that availability and capacity are maximised. The formulated problem focuses on reducing the possession cost and penalty cost. It is modelled as a quadratically constrained mixed integer programming problem and solved using a branch and cut algorithm. A case study on the Swedish iron ore line is used to demonstrate the use of the scheduling approach for effective track possession management.
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| 13. |
- Gustafson, Anna, et al.
(författare)
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Optimizing productivity through performance measures for underground mining industry
- 2008
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Ingår i: MassMin 2008. - Luleå : Luleå tekniska universitet. - 9789163323317 ; , s. 371-378
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Konferensbidrag (refereegranskat)abstract
- Performance needs to be measured in order to manage the business goals. Performance measurement (PM) has caught the imagination of almost all industries in the last decade. A number of PM frameworks are in use by different industries. Due to global competition and high dynamic market demand, the pressure on the process industries like; the mining industries, is too high. In order to manage and meet the challenging market demands of high productivity, mining industries are trying to apply the concept of PM and performance measures. Before applying performance measures for PM, the production process need to be organized and the management needs to be fully committed for PM implementation. PM measures can be divided into hard and soft measures, which are necessary to monitor, control and measure the productivity. Hard measures like the technical, productivity and financial measures can be well defined and relatively easy to control, where as soft parameters pertaining to human factors like; competence, motivation and organizational climate are critical and hard to measure. In this paper, the authors have discussed the concept of performance measurement and measures for achieving desired productivity. Based on their experience of a related project, the authors have discussed the performance measures for LKAB underground mining industry.
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| 14. |
- Haddadzade, Mohammad, et al.
(författare)
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Prediction of track geometry degradation by artificial neural networks
- 2019
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Ingår i: Proceedings of the 29th European Safety and Reliability Conference (ESREL 2019). - Singapore : Research Publishing Services.
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Konferensbidrag (refereegranskat)abstract
- Accurate prediction of track geometry degradation is essential for an efficient track geometry maintenance planning and scheduling. Track geometry prediction is a complex task as many quantitative and qualitative parameters affect track geometry degradation. Artificial neural networks (ANNs) have shown a great capability in prediction of such complex systems, although they are not complicated. In this paper, a three-layered feedforward network is employed to predict track geometry degradation for each track section with-in a track line for a period of two years. A set of influencing factors along with track geometry degradation history are used as inputs to the model. The weight and bias values in the ANN model are optimised using Levenberg and Marquardt optimization algorithm. Data from the Swedish railway network are used to train and verify the proposed model. The relative importance of input parameters on track geometry degradation is determined by Garson`s algorithm. The results indicate that ANN is able to predict the future state of the track in next two years even in the existence of tamping activity within the degradation history.
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| 15. |
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| 16. |
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| 17. |
- Jönsson, Jens, et al.
(författare)
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Measurement of vertical geometry variations in railway turnouts exposed to different operating conditions
- 2016
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 230:2, s. 486-501
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Tidskriftsartikel (refereegranskat)abstract
- Turnouts are critical units in a railway system; they perform the switching procedure that allows trains to change between routes. Monitoring the track geometry of a turnout is necessary for maintenance planning and design optimisation. Monitoring is usually done by track recording cars, however, to isolate the ageing and dynamic behaviour of the track it is also necessary to study the unstressed track geometry of the turnouts. Such measurements can be used to develop degradation models to optimise maintenance and design, thereby increasing availability and reducing life cycle cost. This paper introduces a new method to measure the vertical position of the track geometry over time during non-operational conditions (unstressed) to show track degradation. The new method includes a smart system that uses relative measurement reference points to create a better accuracy and lower costs compared with fixed reference points. It evaluates various types of measurement equipment and uses levelling equipment to measure the unstressed vertical geometry of 13 turnouts located on Swedish railway lines, with three follow-up measurements over a year and a half. The turnouts were categorised into four groups: based on their accumulated capacity in million gross tonnes (MGT) and whether they were on a straight or curved main track. Surprisingly, the first three measurements showed the geometry of turnouts on the straight main track to have a vertical elevation tendency towards the mid-section, whereas the turnouts on the curved main track had a general vertical downwards bend tendency towards the mid-section. The results also showed that a higher capacity in MGT has a greater influence on track geometry changes over time.
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| 18. |
- Khajehei, Hamid, 1987-, et al.
(författare)
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Allocation of effective maintenance limit for railway track geometry
- 2019
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Ingår i: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980. ; 15:12, s. 1597-1612
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study has been to develop an approach to the allocation of an effective maintenancelimit for track geometry maintenance that leads to a minimisation of the total annual maintenancecost. A cost model was developed by considering the cost associated with inspection, preventivemaintenance, normal corrective maintenance and emergency corrective maintenance. The standarddeviation and extreme values of isolated defects of the longitudinal level were used as quality indicatorsfor preventive and corrective maintenance activities. The Monte Carlo technique was used tosimulate the track geometry behaviour under different maintenance limit scenarios and the effectivelimit was determined which minimises the total maintenance cost. The applicability of the model wastested in a case study on the Main Western Line in Sweden. Finally, a sensitivity analysis was carriedout on the inspection intervals, the emergency corrective maintenance cost and the maintenanceresponse time. The results show that there is an optimal region for selecting an effective limit.However, by considering the safety aspects in track geometry maintenance planning, it is suggestedthat the lower bound of the optimal region should be selected.
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| 19. |
- Khajehei, Hamid, 1987-, et al.
(författare)
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Application of First- and Second-Order Derivatives of Track Irregularity to Plan Local Maintenance Activities
- 2020
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Ingår i: e-proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL2020 PSAM15). - Singapore : Research Publishing Services. ; , s. 942-948
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Konferensbidrag (refereegranskat)abstract
- A large part of the railway track geometry maintenance burden concerns local maintenance activates conducted to rectify isolated defects. Isolated defects are short irregularities in the track geometry that can dramatically increase the dynamic forces between the wheel and rail, which in turn will accelerate the growth or occurrence of internal rail defects. The dynamic force between the wheel and rail is dependent on the shape of the isolated geometry defects. However, the severity of isolated defects is mainly defined only by their amplitude. Therefore, in addition to amplitude, other characteristics of geometry defects must be considered to analyze severity of defects and to prioritize local maintenance actions. This study aims to use the first- and second-order derivatives of the longitudinal level defects to plan local maintenance activities. The derivatives of geometry defects provide useful information about the shape of defects. The information is used to categorize the isolated defects based on their severities and prioritize maintenance actions. In this regard, K-means clustering technique is applied. The results of this study will support the decision-making process regarding the planning of local maintenance activities. The foot-by-foot track geometry data collected from Main Western Line in Sweden is used to implement and test the model.
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| 20. |
- Khajehei, Hamid, 1987-, et al.
(författare)
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Application of principal component analysis and artificial neural network in prediction of track geometry degradation
- 2019
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Ingår i: Proceedings of the 5th international workshop and congress on eMaintenace. - : Luleå University of Technology. ; , s. 63-67
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Konferensbidrag (refereegranskat)abstract
- Railway track geometry subjects to degradation with age and usage and highly affects track functionality. An accurate prediction of track geometry degradation is essential to enhance the performance of maintenance planning and scheduling. In this study, artificial neural network is used to predict track geometry degradation rate. The data of five lines from Swedish railway network are used to develop the model. The standard deviation of the longitudinal level is used as quality indicator for track geometry degradation. For all track sections, a set of features which may contribute in track geometry degradation are collected. Principal component analysis method is used to reduce the dimension of the features to facilitate the training of the ANN model. Then, the new principal features considered as inputs to ANN model. The results indicate that the proposed method can be used to predict track geometry degradation along the track line.
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| 21. |
- Khajehei, Hamid, 1987-, et al.
(författare)
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Investigation of Track Geometry Defects on a Heavy-Haul Railway Line
- 2021
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Ingår i: Journal of Transportation Engineering, Part A: Systems. - : American Society of Civil Engineers (ASCE). - 2473-2907 .- 2473-2893. ; 147:9
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an in-depth case study of a heavy-haul railway line in Sweden to analyze the twist and longitudinal level geometry defects. A linear model was applied to model the evolution of the amplitude of the longitudinal level defects and twist over time. Despite the effect of the defect shapes on the dynamic track loads, the amplitude of the defects still is the only criterion used for the assessment of geometry defect severity. The application of first- and second-order derivatives to capture information about the shape of defects was investigated in the case study. In addition, the RUSBoost algorithm was used to classify track sections into healthy and unhealthy sections using the imbalance class data set. In this algorithm, the standard deviation and the kurtosis of the geometry parameters were used as explanatory variables. Finally, the abnormal track geometry degradation patterns identified in the case study were explored in detail. The results of the analysis can be used directly in maintenance modeling and used for the purpose of maintenance scheduling.
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| 22. |
- Khajehei, Hamid, 1987-, et al.
(författare)
-
Optimal opportunistic tamping scheduling for railway track geometry
- 2021
-
Ingår i: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980. ; 17:10, s. 1299-1314
-
Tidskriftsartikel (refereegranskat)abstract
- This study has been dedicated to the optimization of opportunistic tamping scheduling. The aim ofthis study has been to schedule tamping activities in such a way that the total maintenance costs andthe number of unplanned tamping activities are minimized. To achieve this, the track geometry tampingscheduling problem was defined and formulated as a mixed integer linear programming (MILP)model and a genetic algorithm was used to solve the problem. Both the standard deviation of thelongitudinal level and the extreme values of isolated defects were used to characterize the trackgeometry quality and to plan maintenance activities. The performance of the proposed model wastested on data collected from the Main Western Line in Sweden. The results show that different scenariosfor controlling and managing isolated defects will result in optimal scheduling plan. It is alsofound that to achieve more realistic results, the speed of the tamping machine and the unused life ofthe track sections should be considered in the model. Moreover, the results show that prediction ofgeometry condition without considering the destructive effect of tamping will lead to an underestimationof the maintenance needs by 2%.
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| 23. |
- Khajehei, Hamid, 1987-, et al.
(författare)
-
Prediction of track geometry degradation using artificial neural network: a case study
- 2022
-
Ingår i: International Journal of Rail transportation. - : Taylor & Francis. - 2324-8378 .- 2324-8386. ; 10:1, s. 24-43
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study has been to predict the track geometry degradation rate using artificial neural network. Tack geometry measurements, asset information, and maintenance history for five line sections from the Swedish railway network were collected, processed, and prepared to develop the ANN model. The information of track was taken into account and different features of track sections were considered as model input variables. In addition, Garson method was applied to explore the relative importance of the variables affecting geometry degradation rate. By analysing the performance of the model, we found out that the ANN has an acceptable capability in explaining the variability of degradation rates in different locations of the track. In addition, it is found that the maintenance history, the degradation level after tamping, and the frequency of trains passing along the track have the strongest contributions among the considered set of features in prediction of degradation rate.
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| 24. |
- Khosravi, Mahdi, et al.
(författare)
-
A Multi-objective approach for position alignment of track geometry measurements
- 2023
-
Ingår i: Engineering Failure Analysis. - : Elsevier. - 1350-6307 .- 1873-1961. ; 149
-
Tidskriftsartikel (refereegranskat)abstract
- This study aimed to develop a multi-objective approach for reducing the positional errors in geometry measurements of track as a linear asset. Accordingly, we evaluated and compared two alignment methods – recursive segment-wise peak alignment (RSPA) and modified correlation optimised warping (MCOW). Furthermore, a novel rule-based approach was introduced to avoid data loss while aligning the datasets of the measurements of linear assets. A case study was conducted to implement and assess the performance of these methods in reducing the positional errors in track geometry measurements. The results revealed that the rule-based method preserves all the single defects present in the datasets. Furthermore, RSPA outperforms MCOW when aligning peaks, whereas MCOW is more efficient when all the data points in the datasets have equal priority.
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| 25. |
- Khosravi, Mahdi, 1988-, et al.
(författare)
-
Modification of correlation optimized warping method for position alignment of condition measurements of linear assets
- 2022
-
Ingår i: Measurement. - : Elsevier. - 0263-2241 .- 1873-412X. ; 201
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a modification to a well-known alignment method, correlation optimized warping (COW), to improve the efficiency of the method and reduce the positional errors in the measurements of linear assets. The modified method relaxes the restrictions of COW in aligning the start and end of datasets and decreases the computational time. Furthermore, the method takes advantage of the interdependencies between simultaneously measured channels to overcome the missing data problem. A case study on railway track geometry measurements was conducted to implement the proposed method and assess its performance in reducing the positioning inaccuracy of the measurements. The findings revealed that the modified method could decrease the positional errors of defects to below 25 cm in 94% of the trials.
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| 26. |
- Khosravi, Mahdi, 1988-, et al.
(författare)
-
Optimization of Railway tamping scheduling
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This research is devoted to optimizing opportunistic tamping scheduling to present a practical and cost-effective approach that considers both preventive and corrective tamping activities. To accomplish this, we formulated the track geometry tamping scheduling problem as a mixed integer linear programming (MILP) model and employed a genetic algorithm for its resolution. Key track quality indicators, including the standard deviation of the longitudinal level and single defects in each segment, were considered.We developed predictive models for the evolution of standard deviation and single defects over time, which were utilized to schedule preventive tamping activities and anticipate potential corrective actions. Additionally, we investigated the impact of both preventive and corrective tamping activities on the values of standard deviation and single defects.A case study on data from the Main Western Line in Sweden demonstrated that the fixed cost for occupying each maintenance window significantly influenced the total tamping cost. Moreover, the maintenance cycle interval notably affected the number of required corrective tamping activities. Specifically, a 3-month interval led to over 50% fewer corrective tamping activities compared to a 9-month interval. The results revealed that a 6-month interval struck a favorable balance between corrective and preventive tamping activities and the total cost for our case study.
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| 27. |
- Khosravi, Mahdi, 1988-, et al.
(författare)
-
Reducing the Positional Errors of Railway Track Geometry Measurements Using Alignment Methods : a Comparative Case Study
- 2021
-
Ingår i: Measurement. - : Elsevier. - 0263-2241 .- 1873-412X. ; 178
-
Tidskriftsartikel (refereegranskat)abstract
- To predict the occurrence of geometry defects and to achieve a reliable maintenance strategy, accurate positioning of track geometry measurements is of great importance. This paper aims to reduce the positional errors in track geometry measurements by finding an efficient alignment method. Therefore, five alignment methods, i.e. the cross-correlation function, recursive alignment by fast Fourier transform, dynamic time warping, correlation optimized warping, and a combined method, were evaluated and compared concerning their ability to align the measurements precisely, keep the original shape of the measurements, and minimise the use of time and memory. Furthermore, the influence of choosing a proper reference dataset was investigated. A case study based on track geometry data from the Main Western Line in Sweden was conducted to implement and assess the methods. Findings revealed that the combined method could decrease the positional errors of single defects to below 0.25 m in 90% of the trials.
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| 28. |
- Khosravi, Mahdi, 1988-, et al.
(författare)
-
Track Geometry Measurements Alignment : A Comparative Study of Three Relative Position-Based Methods
- 2020
-
Ingår i: e-proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL2020 PSAM15). - Singapore : Research Publishing Services. ; , s. 949-956
-
Konferensbidrag (refereegranskat)abstract
- A great part of the cost of railway maintenance is related to the track geometry. Reliable and complete track geometry data form the foundation of an efficient and effective condition-based maintenance strategy. Generally, track geometry measurement data suffer from positional errors. Because the aim of track geometry degradation modeling has been to analyze the evolution of location-specific defects over time, accurate information on the position of defects is of crucial importance. Therefore, collected track geometry measurements in different inspection runs need to be pre-processed before they are used to model geometry degradation or implement a condition-based maintenance strategy. In this study, three relative position-based approaches are applied to align the positional measurement data obtained from different inspection runs. The two main types of data positional errors are shifted and stretched waveforms. In this regard, three time series alignment algorithms, i.e., crosscorrelation function, dynamic time warping, and dynamic time alignment kernel, are applied to align both shifted and stretched waveforms. Foot-by-foot track geometry data obtained from the main Western line in Sweden are used to implement and test the models. On the basis of the results, dynamic time warping outperforms the other two techniques to align shifted and stretched datasets.
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| 29. |
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| 30. |
- Melander, Eva, et al.
(författare)
-
Utilisation of antibiotics in young children: opposite relationships to adult educational levels in Danish and Swedish counties.
- 2003
-
Ingår i: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 1432-1041 .- 0031-6970. ; 59:4, s. 331-335
-
Tidskriftsartikel (refereegranskat)abstract
- Background. Antibiotic utilisation varies profoundly among and within countries, and the extent of antibiotic utilisation correlates with the frequency of bacterial resistance, particularly among children. Hence, it is important to assess which factors may influence prescribing. In addition to variations in morbidity, health-care organisation, drug regulatory and supply systems, prescriber's attitudes, parents' behaviour, attitudes and socio-economic positions seem important. We compared socio-economic position (educational level of adults) and antibiotic utilisation in children in the municipalities within a Danish and a Swedish county which are geographically close, have similar social and economic development, and similar drug regulatory and supply systems. Methods. Data on antibiotic utilisation (1998), expressed in defined daily doses per 1000 inhabitants per day (DDD/TID), were obtained from the Copenhagen County Health Insurance register and from the National Corporation of Swedish Pharmacies. Data on municipal educational levels were obtained from Statistics Denmark and Statistics Sweden. Results. The utilisation of antibiotics in 0- to 6-year-old children was higher in the Swedish than in the Danish county but varied between the municipalities within both the Swedish (9.6-17.7 DDD/TID) and the Danish (8.0-12.9 DDD/TID) counties. Most notably, utilisation rates correlated negatively with the education levels in the Danish (r=-0.539, P=0.021) but positively in the Swedish (r=+0.390, P=0.025) municipalities. Conclusion. The observed variations in antibiotic prescribing may reflect different parental and/or prescriber attitudes towards use of antibiotics and they emphasise that antibiotic prescribing is influenced by factors other than the prevalence of bacterial infections. Relationships between socio-economic position (educational level) and drug utilisation should not be generalised from one area to another.
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| 31. |
- Mishra, Madhav, et al.
(författare)
-
Particle filter-based prognostic approach for railway track geometry
- 2017
-
Ingår i: Mechanical systems and signal processing. - : Elsevier. - 0888-3270 .- 1096-1216. ; 96, s. 226-238
-
Tidskriftsartikel (refereegranskat)abstract
- Track degradation of ballasted railway track systems has to be measured on a regular basis, and these tracks must be maintained by tamping. Tamping aims to restore the geometry to its original shape to ensure an efficient, comfortable and safe transportation system. To minimize the disturbance introduced by tamping, this action has to be planned in advance. Track degradation forecasts derived from regression methods are used to predict when the standard deviation of a specific track section will exceed a predefined maintenance or safety limit. This paper proposes a particle filter-based prognostic approach for railway track degradation; this approach is demonstrated by examining different railway switches. The standard deviation of the longitudinal track degradation is studied, and forecasts of the maintenance limit intersection are derived. The particle filter-based prognostic results are compared with the standard regression method results for four railway switches, and the particle filter method shows similar or better result for the four cases. For longer prediction times, the error of the proposed method is equal to or smaller than that of the regression method. The main advantage of the particle filter-based prognostic approach is its ability to generate a probabilistic result based on input parameters with uncertainties. The distributions of the input parameters propagate through the filter, and the remaining useful life is presented using a particle distribution.
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| 32. |
- Nissen, Arne
(författare)
-
Analys av statistik om spårväxlars underhållsbehov
- 2005
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Banverket har behov att det genomförs analyser till orsaker till funktionstörningar och förseningstid vid infrastrukturen. Spårväxlar är en av de anläggningar som har många funktionstörningar. Syftet med studien har varit att ta fram ett arbetssätt för att värdera enskilda spårväxlars funktionssäkerhet. Det långsiktiga målet är att minska antalet störningar på Banverkets spårväxlar och de förseningar det orsakar. En matematisk modell har använts för att presentera den information som finns samlad i Banverkets datasystem om spårväxlar. Modellen baseras på teorin om den inhomogena poissonprocessen och visas grafiskt i ett kalkylblad. Kända faktorer kan anges för varje spårväxel och det gör det möjligt att testa hur stort inflytande enskilda faktorer har. En litteraturstudie har genomförts för att ta fram förslag på faktorer. De föreslagna faktorerna kan indelas i: Startvillkor Tågtrafik Ålder Klimat Med hjälp av faktorerna bestäms om en spårväxel kan anses vara normal. Förväntas den ha fler besiktningsanmärkningar eller funktionstörningar än normalt placeras den i en "riskgrupp". Med uppgifter om vilken grupp spårväxeln tillhör, typ av spårväxel, årligt tonnage och ålder kan antalet besiktningsanmärkningar och funktionstörningar förutsägas av modellen. Spårväxlar som, efter att uppdelningen med faktorerna är gjord, upptäcks ligga utanför prediktionsintervallet för modellen kan enkelt identifieras. Metoden har tillämpats i några delstudier och använts för att förklara antalet besiktningsanmärkningar och funktionstörningar för enskilda spårväxlar eller grupper av spårväxlar på bandels nivå. Någon heltäckande förklaring till alla spårväxlars antal besiktningsanmärkningar och funktionstörningar har inte rymts inom detta projekt och det finns behov av att komplettera den information som varit tillgänglig med bland annat: Användandet av avvikande tågspår Tågens vikt, antal axlar och hastighet Banförvaltarens underhållsstrategi Arbetsättet har visat sig vara tillämpbart och i framtiden kommer metoden att utvecklas så att den kan användas för att genomföra bedömningar av livscykelkostnaden för spårväxlar.
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| 33. |
- Nissen, Arne
(författare)
-
Classification and cost analysis of switches and crossings for the Swedish railway
- 2009
-
Ingår i: Journal of Quality in Maintenance Engineering. - : Emerald. - 1355-2511 .- 1758-7832. ; 15:2, s. 202-220
-
Tidskriftsartikel (refereegranskat)abstract
- PurposeSwitches and crossings (S&Cs) are an important component of Banverket's (the Swedish National Rail Administration's) infrastructure and are associated with 13 per cent of the total maintenance cost. Therefore, it is important that a detailed study of different aspects of the costs of S&Cs should be undertaken to analyze individual maintenance costs. This will in the future give the possibility of enhancing the management of infrastructure. Design/methodology/approachA case study is undertaken to study, identify and classify the costs of S&Cs for Banverket. Data are taken from Banverket's maintenance information systems and accounting system. Findings A rough estimation of the cost for individual S&Cs can be identified in this way. The cost varies very much and a more detailed study is needed to validate the cost on this level. The average cost of a group of S&Cs varies less and is therefore more likely to reflect the true cost. The cost varies depending on the amount and type of traffic. Moreover, the type of S&C seems to reflect the cost variation, but further investigation is needed to verify this conclusion. Research limitations/implications The accounting system does not store data for individual assets, and further research would be more fruitful if individual costs could be recorded by the entrepreneur. Larger repairs should be separated from annual maintenance tasks in a future study. Data from this study could be used to build a life cycle cost model for S&Cs. Practical implications Cost identification is a first step in finding a way to organize maintenance in a more cost-effective way. Originality/valueThe paper shows a way to distribute costs (in the accounting system) down to individual subsystems of the infrastructure. This enables analysts to find cost drivers and plan for modification of or reinvestment in the asset.
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| 34. |
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| 35. |
- Nissen, Arne
(författare)
-
Development of life cycle cost model and analyses for railway switches and crossings
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Infrastructure managers need to have a safe and available infrastructure, so that train operators can deliver a transport product at an affordable price. In the future, as traffic volume increases, higher utilisation of the existing capacity, less time for maintenance and fewer unplanned interruptions will be critical for meeting the ever increasing need of transport capacity. Improved performance and added capacity on the existing track can be achieved by optimising the operation and maintenance of infrastructure systems. In general, RAMS (Reliability, Availability and Maintainability and Safety) and LCC (Life cycle cost)-analyses are used as tools to optimize the performance of infrastructure and make it economically viable. RAMS analysis is used to establish the need of maintenance by analysing corrective and preventive maintenance data. LCC is a method of highlighting the cost for investment, operation, maintenance and unplanned interruptions throughout an asset's life cycle. Switches and crossings (S&Cs) are one of the major subsystems in the superstructure of the railway. The major function of an S&C is to allow trains to shift from one track to another track in a safe way. To enable this, an S&C consists of movable and fixed mechanical parts, as well as signalling and electrical systems. Each of these systems has a need for maintenance and is susceptible to failures which ultimately lead to train disturbances. The investment costs for new S&Cs are high and the technical lifespan is often very long (over 40 years). Therefore, the maintenance cost is considerable. If the S&C is causing many train interruptions, the cost for train delays is also an important factor for consideration. During the course of this research study, reliability and maintainability characteristics of switches and crossings are analysed using real data from Banverket. In addition, an LCC model is developed using information from Banverket. By applying this model, correct maintenance and investment decisions can be made. Some parts of the Research work have been performed within the European Framework of FP 6 IP Project INNOTRACK with a goal of reducing the LCC of infrastructure by 30 %.This research study confirms that the infrastructure managers have enough data to apply the LCC models for the S&Cs. The model developed can be used to evaluate new S&C designs and to take decisions regarding alternatives for S&C specification to be used under different traffic situations. Also the issue of decisions regarding renewal versus extended life through maintenance is highlighted by use of the LCC model.
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| 36. |
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| 37. |
- Nissen, Arne
(författare)
-
LCC analysis for switches and crossings : a case study from the Swedish Railway Network
- 2009
-
Ingår i: International Journal of COMADEM. - 1363-7681. ; 12:2, s. 10-19
-
Tidskriftsartikel (refereegranskat)abstract
- This paper makes an attempt to analyze the LCC values of switches and crossings (S&C) on Swedish Railway Track. The scope of the paper is to explore the possibility of using LCC as a decision tool for an infrastructure manager. The S & C cost from the Swedish Rail Administration (Banverket) were collected for the LCC analysis as a part of the case study. A cost model based on the acquisition phase and the operation and maintenance phase has been developed and tested. In this model the LCC values of three types of S & Cs are compared. The model can also be used to find cost drivers, as well as to perform sensitivity analysis to find parameters that have a large influence on the result. The model has been built with the assumption that a multiple type of maintenance action is undertaken for each subsystem. Within the model, there is a possibility of defining periodical maintenance intervals besides the annual maintenance cost. The LCC value may be presented as an annuity cost, which enables a comparison between assets that have different technical lifetimes.
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| 38. |
- Nissen, Arne, et al.
(författare)
-
Measuring the use of deviating train track
- 2006
-
Ingår i: Condition Monitoring and Diagnostic Engineering Management. - Luleå : Luleå tekniska universitet. - 9789163188060 ; , s. 348-349
-
Konferensbidrag (refereegranskat)abstract
- Turnouts used at the Swedish rail contribute to about 10 % of the yearly operation and maintenance cost and especially turnout extensively used for deviating track have high maintenance cost and more failures than those used mostly for main track. Therefore it is critical to have more information of how much the deviating track is used in practise. A measurement has been made to establish train speed, train weight, direction through the turnout and which path that has been used on a specific turnout. This type of measurement should be done on turnouts that have more problems to onfirm if the traffic is a major cause or not. There are two major sources for establish the information, one is measuring it at place and the other is to use information gathered by Banverket. The possibility and the cost of this type of investigation are discussed as well as the difference between the planned and actual use of the turnout.
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| 39. |
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| 40. |
- Nissen, Arne
(författare)
-
Spårväxlar : felutfall och underhållsinsatser
- 2002
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Spårväxlar utgör en mycket vital del av järnvägsnätet. En förstudie har gjorts i syfte att se om den informations som finns lagrad om spårväxlar i olika databaser kan nyttjas för att få fram trender för nedbrytning, förbättra underhållet av spårväxlar, finna underlag för att förbättra konstruktionen, minska funktionsstörningar och besiktningsanmärkningar. Informationen som finns räcker för att göra en analys, men krav måste ställas på att förbättra dokumentation och uppföljning. I analysen framkommer att 12% av växlar av typ 1:9 och 1:15 tillsammans har 24% av besiktningsanmärkninganrna och 33% av funktionstörningarna. En djupare analys av just dessa växlar bör kunna ge en förståelse för ett flertal faktorer som anses vara viktiga i sammanhanget. Ett allmänt samband mellan besiktningsanmärkningar och funktionsstörningar diskuteras i rapporten. I rapporten framkommer en del förbättringsområden: Trender för nedbrytning är svåra att bygga med dagens underlag. Man bör återrapportera mätvärden även innan larmgränser uppnås Olika datasystem för återrapportering kan inte enkelt samköras, på grund av att beteckningar på växlar skiljer sig mellan systemen Nya konstruktionslösningar för TKK, omläggningsanordning och växelvärme är ytterst befogade och kommer, när de införs, drastiskt kunna minska antalet funktionsstörningar Funktionsstörningarna kan minskas genom systematiskt arbete och översyn av rutiner Besiktningsanmärkningar åtgärdas ibland inte förrän långt senare vilket genererar återkommande anmärkningar på samma fel. Det faktiska antalet nya besiktningsanmärkningarna är antagligen 10 % lägre än vad som syns i statistiken. Exempel på viktiga faktorer är: Geometri Underhållsinsatser Trafikbelastning Banunderbyggnad Det har dock visat sig svårt att använda enskilda faktorer till att studera hela materialet eftersom många växlar inte ger funktionsstörningar och därmed blir medelvärden rätt så lika. Stor energi har använts för att sammanställa ett representativt urval av växlar.
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| 41. |
- Odolinski, Kristofer, 1984-, et al.
(författare)
-
Finding a better renewal time and improved contract design for switches and crossings
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Switches and crossings are critical assets in railway systems and their maintenance and renewal costs can be substantial. This paper evaluates the economic impact of cumulative loads on such assets and the effect of different contract designs for railway maintenance. Results from survival analyses are combined with a life cycle costing model to analyse costs for maintenance, train delays, and renewals. The findings provide insights into improving the timing of asset renewal as well as the impact of different reimbursement rules in the design of maintenance contracts. The estimated optimal lifetimes of different types of switches and crossings are similar to their technical lifetimes, yet there a couple of exceptions. The estimated effects of the reimbursement rule provide unique results on the risk premiums allowed in order to achieve a break-even between different maintenance contract designs.
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| 42. |
- Odolinski, Kristofer, 1984-, et al.
(författare)
-
Finding a better renewal time and improved contract design for switches and crossings
- 2024
-
Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 140-141
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Making informed decisions regarding the timing of S&C renewal is crucial for infrastructure managers (IMs) to minimize socio-economic costs. This includes the design of maintenance contracts since it will influence the life cycle cost (LCC) of the asset. The purpose of this paper is to estimate the economic impact of cumulative tonnes on S&Cs and evaluate the effect of maintenance contract design. The aim is that the established relationships can be used to find a better time for switch renewal and improve the design of maintenance contracts with respect to a reimbursement rule. Under this rule, the Swedish IM compensates the contractor for costs exceeding a certain threshold, whilst the contractor is responsible for costs below the threshold. The threshold varies between maintenance contracts, where a higher threshold creates stronger incentives for preventing costly corrective activities.In the context of railway systems, LCC has been extensively used to study the renewal and maintenance actions associated with various infrastructure assets. Some studies have demonstrated the use of LCC to optimise maintenance and renewal planning by combining it with other methods, such as reliability, availability, maintainability, and safety (RAMS) analysis, and cost-benefit methods. However, to the best of the authors’ knowledge, this paper is the first to evaluate reimbursement rules in railway maintenance contracts with respect their impact on LCCs. Based on empirical data on preventive and corrective maintenance activities, a survival analysis is used to study the timing of events and the impact of various factors such as cumulative load, S&C characteristics, and maintenance contract design. The regression estimates are linked to unit costs for maintenance, train delays, and renewals in an LCC model.The estimated cumulative hazards for preventive maintenance, corrective maintenance, and failures causing train delays illustrate the number of activities/events accumulating until 75 years have elapsed since the S&C was installed. The estimation results show that a higher reimbursement threshold (which implies a higher cost responsibility for the contractor) generates fewer corrective activities.
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| 43. |
- Prokopov, Andrej
(författare)
-
Selection and Design of Optimal Railway Track Solution : A Conceptual Framework
- 2024
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Increasing reliability and availability demands on railway track assets and the sustainable development goal concerning climate impact challenge infrastructure managers to implement a decision-support system for selecting an optimal track solution from a life cycle perspective. Experience has shown that track condition deterioration caused by train loads is the primary reason a track asset ceases to provide the required reliability and availability. Previous research shows that existing track deterioration models consider load and other track deterioration factors, which vary from model to model. Moreover, the response of existing track forms, namely the ballasted and ballastless track, to applied loads under specific operating conditions varies. Another interesting aspect that motivated infrastructure managers to rethink and reconsider the use of new solutions is the evolution of the design of track systems during recent decades. This development has not only made the new generation track forms both economical and dependable but also environmentally friendly. Considering these issues, an in-depth study of the long-term behaviour of the track and the impact of different factors on its deterioration is of great interest in the industry. The knowledge from such study is necessary for the development of a practical decision support system for selecting the optimal track solution among ballasted track solutions, ballastless track solutions, and combined track solutions (CTS), which consist of both forms. To this end, the current study addresses the root cause and mechanisms of track deterioration, the diversity of track deterioration factors, and how the impact of deterioration factors varies in different track solutions. Furthermore, this study examines the effect of several track design and maintenance factors on climate, which was not adequately addressed in previous research. The methodology used in this research is both qualitative and quantitative approaches. In the qualitative approach, a literature review was carried out to identify and describe the factors that deteriorate the condition and the long-term behaviour of track solutions. Furthermore, a conceptual framework was developed as the first stage for the development of a decision support model for the design and selection of optimal railway track solutions The quantitative approach includes a case study on the climate impact of alternative tunnel-based track solutions in a railway tunnel. The result of this study include: a comprehensive framework of track deterioration factors and a climate model for estimating the estimation of carbon footprint of track solutions in tunnel with specific design and operational parameters.The findings from the literature review on track deterioration factors are as follows: · the factors with the most significant impact on track behaviour according to literature include: · previous research has not adequately addressed the following deterioration factors: (i) the design of the track forms and (ii) the properties of the analysed track subsystems and track components, (iii) the deterioration factor specific to CTS, namely the design, location, and quantity of track transitions, (iv) the elastic modulus of track support and the amplitude and the wavelength of differential settlement in the track support.The findings from the case study on the evaluation of climate impact of competing track solutions in a railway tunnel are as follows:· the life cycle carbon dioxide equivalent CO2 e emissions by a ballastless track during its life cycle are 10 % lower than that of the ballasted track for the track and tunnel design under consideration. · the primary driver of the total emission for both track form solutions is the emissions generated for the manufacturing of rails. · the second important emission factor for the ballasted track solution is the emission from the renewal of the track form during its life cycle, and concrete manufacturing for the ballastless track solution. This research has developed a comprehensive conceptual framework for designing and selecting optimal railway track solutions. The development of the final decision support model, which integrates life cycle cost, climate impact, and other relevant decision perspectives, is a future work of this study. Another study suggested in continuation of this research is the implementation of the decision support model for suggesting design specifications and requirements of optimal track forms.
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| 44. |
- Sandström, Johan, 1978, et al.
(författare)
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Deterioration of insulated rail joints – a three-year field study
- 2012
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Ingår i: Proceedings of the 9th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems (CM2012). ; , s. 301-308
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Konferensbidrag (refereegranskat)abstract
- Four operational joints at the Swedish West Coast Line have been monitored in field from installation and during three years of operation to follow degradation. Even though operational loads were comparatively low, material damage was found to occur early after installation. All joints showed a similar damage pattern with dominating deformation on the side towards a nearby station. In addition some joints showed “cavity-like” damage on the off-station side. The paper reports observations on continuing degradation of the joints as well as hardness evolution and increased joint dip over time.
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| 45. |
- Soleimanmeigouni, Iman, et al.
(författare)
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Cost-Based Optimization of Track Geometry Inspection
- 2016
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Konferensbidrag (refereegranskat)abstract
- Track geometry bear huge static and dynamic forces that accelerate degradation process. As a result, railway track should be inspected regularly to detect geometry faults and to plan maintenance actions in advanced. An inspection plan that minimizes track maintenance cost is highly desirable by infrastructure managers. This paper proposes constructing an integrated model to identify the optimum track geometry inspection interval. To this end, it develops a long term prediction model combining degradation, shock event, and tamping recovery models. It applies the Wiener process to model track geometry degradation, simulates shock event times using an exponential distribution, and uses a probabilistic model to model recovery after tamping. With the proposed integrated model and simulation, it is possible to identify the optimum track geometry inspection frequencies that minimize total track maintenance costs.
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| 46. |
- Soleimanmeigouni, Iman, 1988-, et al.
(författare)
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Investigation of the effect of the inspection intervals on the track geometry condition
- 2020
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Ingår i: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980. ; 16:8, s. 1138-1146
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Tidskriftsartikel (refereegranskat)abstract
- In order to evaluate the railway track geometry condition and plan maintenance activities, track inspection cars run over the track at specific times to monitor it and record geometry measurements. Applying an adequate inspection interval is vital to ensure the availability, safety and quality of the railway track, at the lowest possible cost. The aim of this study has been to investigate the effect of different inspection intervals on the track geometry condition. To achieve this, an integrated statistical model was developed to predict the track geometry condition given different inspection intervals. In order to model the evolution of the track geometry condition, a piecewise exponential model was used which considers break points at the maintenance times. Ordinal logistic regression was applied to model the probability of the occurrence of severe isolated defects. The Monte Carlo technique was used to simulate the track geometry behaviour given different inspection intervals. The results of the proposed model support the decision-making process regarding the selection of the most adequate inspection interval. The applicability of the model was tested in a case study on the Main Western Line in Sweden.
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| 47. |
- Soleimanmeigouni, Iman, et al.
(författare)
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Modelling the evolution of ballasted railway track geometry by a two-level piecewise model
- 2018
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Ingår i: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980. ; 14:1, s. 33-45
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Tidskriftsartikel (refereegranskat)abstract
- Accurate prediction and efficient simulation of the evolution of track geometry condition is a prerequisite for planning effective railway track maintenance. In this regard, the degradation and tamping effect should be equipped with proper and efficient probabilistic models. The possible correlation induced by the spatial structure also needs to be taken into account when modelling the track geometry degradation. To address these issues, a two-level piecewise linear model is proposed to model the degradation path. At the first level, the degradation characteristic of each track section is modelled by a piecewise linear model with known break points at the tamping times. At the second level, Autoregressive Moving Average models are used to capture the spatial dependences between the parameters of the regression lines indexed by their locations. To illustrate the model, a comprehensive case study is presented using data from the Main Western Line in Sweden
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| 48. |
- Soleimanmeigouni, Iman, 1988-, et al.
(författare)
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Prediction of railway track geometry defects : a case study
- 2020
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Ingår i: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980. ; 16:7, s. 987-1001
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study has been to develop a data-driven analytical methodology for prediction of isolated track geometry defects, based on the measurement data obtained from a field study. Within the study, a defect-based model has been proposed to identify the degradation pattern of isolated longitudinal level defects. The proposed model considered the occurrence of shock events in the degradation path. Furthermore, the effectiveness of tamping intervention in rectifying the longitudinal level defects was analysed. The results show that the linear model is an appropriate choice for modelling the degradation pattern of longitudinal level defects. In addition, a section-based model has been developed using binary logistic regression to predict the probability of occurrence of isolated defects associated with track sections. The model considered the standard deviation and kurtosis of longitudinal level as explanatory variables. It has been found that the kurtosis of the longitudinal level is a statistically significant predictor of the occurrence of isolated longitudinal level defects in a given track section. The validation results show that the proposed binary logistic regression model can be used to predict the occurrence of isolated defects in a track section.
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