| 1. |
- Abbasi, Saeed, 1973-, et al.
(författare)
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A field test study of airborne wear particles from a running regional train
- 2012
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Ingår i: IMechE, Part F: Journal of Rail and Rapid Transit. - UK : Sage Publications. - 0954-4097 .- 2041-3017. ; 226:1, s. 95-109
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Tidskriftsartikel (refereegranskat)abstract
- Inhalable airborne particles have inverse health affect. In railways, mechanical brakes, the wheel–rail contact, current collectors, ballast, sleepers, and masonry structures yield particulate matter. Field tests examined a Swedish track using a train instrumented with particle measurement devices, brake pad temperature sensors, and speed and brake sensors. The main objective of this field test was to study the characteristics of particles generated from disc brakes on a running train with an on-board measuring set-up.Two airborne particle sampling points were designated, one near a pad–rotor disc brake contact and a second under the frame, not near a mechanical brake or the wheel–rail contact; the numbers and size distributions of the particles detected were registered and evaluated under various conditions (e.g. activating/deactivating electrical brakes or negotiating curves). During braking, three speed/temperature-dependent particle peaks were identified in the fine region, representing particles 280 nm, 350 nm, and 600 nm in diameter. In the coarse region, a peak was discerned for particles 3–6 μm in diameter. Effects of brake pad temperature on particle size distribution were also investigated. Results indicate that the 280 nm peak increased with increasing temperature, and that electrical braking significantly reduced airborne particle numbers. FESEM images captured particles sizing down to 50 nm. The ICP-MS results indicated that Fe, Cu, Zn, Al, Ca, and Mg were the main elements constituting the particles.
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| 2. |
- Aggestam, Emil, 1992, et al.
(författare)
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Innovative requirements and evaluation methods for slab track design
- 2023
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit. - 0954-4097 .- 2041-3017. ; In press
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Tidskriftsartikel (refereegranskat)abstract
- With increasing train speeds and reduced time windows for maintenance work, the interest in the application of slab track technology to increase the capacity of high-speed railways has grown. Slab track may still be considered a relatively young technology, but with several different designs available on the market. Current research on slab tracks commonly focuses on improved methods. In contrast, the formulation of requirements, and evaluation towards these, are seldom investigated. In this paper, state-of-the-art simulation models are employed to illustrate and address the needs for innovative requirements in terms of structural integrity and robustness, life cycle cost (LCC) and environmental footprint of new and existing slab track designs. Based on demonstration examples, it is argued that current standards may lead to overly conservative designs inducing higher LCC and environmental footprint than necessary. Extensions of the standards in terms of LCC and environmental footprint are suggested. The conflict of interest between structural integrity and robustness, LCC and environmental footprint is discussed, and suggestions for how to optimise slab track structures are proposed.
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| 3. |
- Anandika, Rayendra, 1988-, et al.
(författare)
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Limitations of eddy current inspection for the characterization of near-surface cracks in railheads
- 2022
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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. ; 236:5, s. 532-544
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Tidskriftsartikel (refereegranskat)abstract
- Eddy current (EC) testing is the most commonly used method to inspect near-surface cracks in railheads. Monitoring surface defects periodically is important to assess the track quality for serving daily operations. Nevertheless, despite being used in many countries, this method has limitations when characterizing cracks under the rail surface. Theoretically, EC testing is unreliable for the inspection of many cracks situated too close to each other in a concentrated location. This study has aimed to prove these limitations. EC signals from inspected cracks were compared with real crack profile parameters, i.e. depth and area, which were delivered by slicing the inspected cracked spots into 0.65 mm-thick pieces. The results show that the EC signal responses to the parameters of area and depth may lead to misleading measurements of the near-surface crack depth in the railhead. For instance, a shallower crack with a larger area can generate a higher EC signal response than a deeper crack with a smaller area. Another important conclusion is that the EC testing in this experiment could not be used to measure densely located cracks, which are those near-surface cracks which are typically found in a rail track.
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| 4. |
- Andersson, Evert, et al.
(författare)
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Assessment of train-overturning risk due to strong cross-winds
- 2004
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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. ; 218:3, s. 213-223
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the methodology for safety assessment related to the risk of a train overturning in strong cross-winds. As an example, this methodology is applied on the high-speed line Botniabanan being built for a maximum speed of 250 km/h in the northeast coastal region of Sweden. The process starts with a systematic identification of locations along the line having a potential high risk of overturning due to cross-winds. This is followed by a cross-disciplinary study. The first step is to estimate the probabilities of wind velocity and wind directions. The next step is aerodynamic computation of overturning forces and moments acting on relevant types of train. Further, the critical overturning wind velocity is determined by a multi-body simulation technique. Finally, the overturning accident frequency is calculated. The calculated risk is compared with generally accepted risk levels in modern train operation.
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| 5. |
- Arasteh khouy, Iman, et al.
(författare)
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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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| 6. |
- 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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| 7. |
- Arasteh khouy, Iman, et al.
(författare)
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Geometrical degradation of railway turnouts : a case study from a Swedish heavy haul railroad
- 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. ; 228:6, 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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| 8. |
- 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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| 9. |
- Asplund, Matthias, et al.
(författare)
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A Nordic heavy haul experience and best practices
- 2017
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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. ; 231:7, s. 794-804
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Tidskriftsartikel (refereegranskat)abstract
- This article summarizes the experiences gained at the Nordic heavy haul line “Malmbanan” located in Northern Sweden and Norway during the years 2007 to 2015 and the resulting best practice. Unique long-term information of field trials and monitoring from the on-going development for maintenance of rail and wheel has been described. The reported results come from the rail profile measurements using MiniProf and HC-recordings with Eddy-current devices and visual inspection on 43 test sections. The monitoring has been continuous since the project started, to reveal a deep insight into the complex wheel–rail interaction and provide understanding of the effect of applying optimized specifications. This was particularly important in view of the increasing traffic load that contributed to doubling of the yearly grinding campaigns. This article presents in particular the new MB5 profile, the wear rate behaviour between two different curves, impacts of gauge widening on rail rolling contact fatigue and the speed of gauge widening as well as the seasonal impact on the crack propagation. The presently applied maintenance strategy is discussed together with other experiences. The article finishes with some conclusions and an outlook into further work.
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| 10. |
- Asplund, Matthias, et al.
(författare)
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A study of railway wheel profile parameters used as indicators of an increased risk of wheel defects
- 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. 323-334
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Tidskriftsartikel (refereegranskat)abstract
- The capacity demands on the railways will increase in the future, as well as the demands for a robust and available system. The availability of the railway system is dependent on the condition of the infrastructure and the rolling stock. To inspect the rolling stock and to prevent damage to the track due to faulty wheels, infrastructure managers normally install wayside monitoring systems along the track. Such systems indicate, for example, wheels that fall outside the defined safety limits and have to be removed from service to prevent further damage to the track. Due to the nature of many wayside monitoring systems, which only monitor vehicles at definite points along the track, damage may be induced on the track prior to fault detection at the location of the system. Such damage can entail capacity-consuming speed reductions and manual track inspections before the track can be opened for traffic again. The number of wheel defects must therefore be kept to a minimum. In this paper wheel profile parameters measured by a wayside wheel profile measurement system, installed along the Swedish Iron Ore Line, are examined and related to warning and alarm indications from a wheel defect detector installed on the same line. The study shows that an increased wheel wear, detectable by changes in the wheel profile parameters could be used to reduce the risk of capacity-consuming wheel defect failure events and its reactive measures.
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