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| 2. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Evaluating the mix of maintenance activities on railway crossings with respect to life-cycle costs
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Switches & crossings (S&Cs) are vital assets as they allow for increased railway capacity by introducing flexibility and connectivity in railway networks. At the same time, this makes them critical since they can cause costly delays and disruptions if they are not well maintained. This motivates studies to improve maintenance strategies of S&Cs, considering both the life-cycle costs (LCC) of the assets and socio-economic transportation costs for passengers and freight customers. In this paper, the interdependence between deterioration mechanisms, maintenance activities, and expected LCC (including transportation costs) is investigated using a combination of mechanical and econometric modelling. The interrelation between the degradation of contact geometry and track settlement is analysed using simulations of dynamic vehicle–turnout interaction. Long-term mechanical degradation of the S&C is simulated for different maintenance strategies that correspond to different timing of the associated maintenance measures (crossing repair welding and tamping). This provides the basis for analysing the interdependence between preventive and corrective activities using econometric modelling. Based on a case study of a common type of S&Cs in the Swedish infrastructure, the impact of different maintenance strategies on LCC and transportation costs is analysed. Opportunities and challenges in the development of more socio-economically effective maintenance strategies of S&Cs are discussed.
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| 3. |
- Ait Ali, Abderrahman, 1991-, et al.
(författare)
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Evaluating the mix of maintenance activities on railway crossings with respect to life-cycle costs
- 2024
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Ingår i: European Journal of Transport and Infrastructure Research. - : TU Delft. - 1567-7141 .- 1567-7133. ; 24:1, s. 1-29
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Tidskriftsartikel (refereegranskat)abstract
- Switches & crossings (S&Cs) are vital assets as they allow for increased railway capacity by introducing flexibility and connectivity in railway networks. At the same time, this makes them critical since they can cause costly delays and disruptions if they are not well maintained. This motivates studies to improve maintenance strategies of S&Cs, considering both the life-cycle costs (LCCs) of the assets and socio-economic transportation costs for passengers and freight customers. In this paper, the interdependence between deterioration mechanisms, maintenance activities, and expected LCC (including transportation costs) for the crossing panel – an S&C subsystem – is investigated using a combination of mechanical and econometric modelling. The interrelation between the degradation of contact geometry and track settlement is analysed using simulations of dynamic vehicle– turnout interaction. Long-term mechanical degradation of the crossing panel is simulated for different maintenance strategies that correspond to different timing of the associated maintenance measures (crossing repair welding and tamping). This provides the basis for analysing the interdependence between preventive and corrective activities using econometric modelling. Based on a case study of a common type of S&Cs in the Swedish infrastructure, the impact of different maintenance strategies on LCC and transportation costs is analysed. Opportunities and challenges in the development of more economically effective maintenance strategies of S&Cs are discussed.
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| 4. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Evaluating the mix of maintenance activities on railway crossings with respect to life-cycle costs
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 405-406
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Switches and crossings (S&Cs) are critical assets in the Swedish rail infrastructure, with a density of 0.8 S&C per track-km and renewal costs of up to 4.5 million SEK/S&C. The efficiency of maintenance strategies for S&Cs is vital from a (socio-)economic perspective. The focus of this study is on the importance of the mix of maintenance activities performed on a S&C with respect to its life-cycle costs (LCCs). The study investigates the interdependencies between the deterioration mechanisms, preventive and corrective maintenance activities, and expected LCCs, including transportation costs due to traffic disruptions/delays. One or a combination of different approaches are often used in the literature, such as engineering or LCC methods. In this research, a novel approach is introduced that combines mechanical simulations, data analysis, econometrics, and LCC calculations to compare the efficiency of different maintenance strategies. The mechanical simulations consider one S&C on the Swedish railway network. The selection criteria were that the S&C is located on the main line, installed in 2014 (generates the longest observation period given the availability of data), and had no extreme values with respect traffic volume, maintenance activities and failures. The interrelation between the degradation of contact geometry and track settlement is analysed using simulations of dynamic vehicle–turnout interaction. Further, the relationship between frequency of preventive and occurrence of corrective maintenance activities is analyses using an econometric model. Implications of a specific mix of maintenance activities on the S&C lifetime and LCC are evaluated using different cost parameters. Results obtained from mechanical simulations reveal the correlation between poor crossing geometry and higher rates of ballast settlement. The econometric analysis finds a statistically significant impact of (cumulative) preventive maintenance on corrective maintenance, i.e., more preventive maintenance leads to fewer corrective activities. Based on a standard mix of maintenance activities (inferred using econometric regression across all S&Cs), the lifetime of the selected S&C is estimated to 10 years with a lower associated LCC than that resulting from the record of performed maintenance activities at the site. The LCC evaluations highlight the potential to improve the efficiency of S&C maintenance by adopting proactive strategies.
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| 5. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Evaluation of long-term maintenance of switches & crossings with respect to life-cycle costs and socio-economic impact
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Switches & crossings (S&Cs) are vital assets as they allow for increased railway capacity by introducing flexibility and connectivity in railway networks. At the same time this makes them critical, and they can cause major delays and disruptions if they are not well maintained. This motivates studies to improve maintenance strategies of S&Cs, considering both life-cycle costs (LCC) of the assets and other additional socio-economic costs (e.g., transportation costs for passengers and freight customers). In this paper, the interdependence between deterioration mechanisms, maintenance activities, and expected LCC (including transportation costs) is investigated using a combination of mechanical and econometric modelling.The interrelation between the degradation of contact geometry and track settlement is analysed using simulations of dynamic vehicle–turnout interaction. Changes in the timing of the associated maintenance measures (crossing repair welding and tamping) are performed to investigate the impact on damage modes. This is then linked to LCC and transportation costs, which requires a distribution between preventive and corrective activities with respect to the simulated maintenance strategy. This relationship is investigated by means of regression modelling: ??????????=?(??????????,?)where Corrective and Preventive represent the number of failures and the scheduled actions to prevent these failures, respectively. ? holds variables related to the traffic (volume, type of traffic, axle load, etc.) and the infrastructure (type of S&Cs, etc.).
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| 6. |
- Ansin, Caroline, 1996, et al.
(författare)
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Influence of model parameters on the predicted rail profile wear distribution in a curve
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A sensitivity study is performed to determine the effect of model parameters on the predicted wear distribution on rail profiles. The numerical framework uses multibody simulations to evaluate dynamic vehicle-track interaction for different traffic scenarios, and FASTSIM and Archard's wear law to evaluate rail profile wear. Vehicle and track parameters as well as different approaches to contact modeling are considered. A previous study has shown good agreement between predictions and measurements in overall wear, but deviations in wear distribution. The objective of this study is to obtain a better agreement for the profile wear distribution under operational traffic conditions compared to rail profile measurements. The study shows that the inclusion of freight vehicles, different wheel profile samples, and the consideration of a different contact model are some of the most important parameters.
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| 7. |
- Ansin, Caroline, 1996, et al.
(författare)
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Simulation and Field Measurements of the Long-term Rail Surface Damage due to Plasticity, Wear and Surface Rolling Contact Fatigue Cracks in a Curve
- 2022
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Ingår i: CM 2022 - 12th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Conference Proceedings. ; , s. 591-601
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Konferensbidrag (refereegranskat)abstract
- A methodology that simulates the long-term rail surface damage in a cross-section of a curve for a given traffic scenario is presented. The numerical model considers plastic deformation, wear, and initiation of rolling contact fatigue (RCF) surface cracks. The models and simulations are calibrated and validated, respectively, against field profile measurement data.
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| 8. |
- Bezin, Yann, et al.
(författare)
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Multibody simulation benchmark for dynamic vehicle-track interaction in switches and crossings: modelling description and simulation tasks
- 2023
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 61:3, s. 644-659
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the final description for the S&C Benchmark that was launched at the IAVSD 2019 conference held in Gothenburg, Sweden and completed by eighteen participants by the end of 2020. The purpose of this paper is to allow for the replication of the Benchmark exercise after publication for those who wish to do so in the future, and it includes a link to the repository containing all necessary input data. The original task description, including a description of the Benchmark submission, is presented in full. The results from the Benchmark are available in [Bezin Y, Pålsson BA, Kik W, et al. Multibody simulation Benchmark for dynamic vehicle-track interaction in switches and crossings: results and method statements. Submitted to VSD, 2021].
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| 9. |
- Bezin, Y., et al.
(författare)
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Multibody simulation benchmark for dynamic vehicle-track interaction in switches and crossings: results and method statements
- 2023
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 61:3, s. 660-697
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Tidskriftsartikel (refereegranskat)abstract
- A Benchmark of railway multibody dynamics software application to switches and crossings (S&C) is presented, comparing all major commercially available software and a few independent codes. Two different representative S&C have been implemented, using the Manchester Benchmark passenger vehicle. The final results show that all software offer a reliable and efficient way to understand the kinematic and dynamics forces between the wheels and the track elements. The highest challenges are found when modelling a combination of multiple rails in simultaneous contact with a wheel (check-stock or switch-stock), large longitudinal variations in rail shape (crossings) and high lateral steering forces (diverging cases in tight radius). In those cases, the codes able to account for the exact relative motion of each wheels with respect to each rails independently are the most apt. The most significant variations between software are found in the contact prediction with an influence on the detailed contact tangential and normal forces. The user variability is found to be very small, with the most time-consuming and error prone being the task of handling the input data for the variable rails definition. All software could benefit from improvements to assist the user and ensure higher reliability and efficiency generally.
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| 10. |
- Bolsman, Caspar T., et al.
(författare)
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The Use of Resonant Structures for Miniaturizing FMAVs
- 2007
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Ingår i: Proceedings of the 3rd US-European Competition and Workshop on Micro Air Vehicle Systems (MAV07) & European Micro Air Vehicle Conference and Flight Competition (EMAV2007), 17-21 September 2007, Toulouse, France. ; , s. 12-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The use of resonant structures in FMAVs is an idea inspired by nature. The application of resonancein an oscillating system requires a careful analysis of the involved structures in insects. The applicationof this concept in FMAVs yields opportunities for size reduction. As one moves away from standard constructionalprinciples. The latter become less feasible at the small scale. It is mandatory to include thecontrol mechanism in the design loop from the start. Control over wing kinematics in insects relies oncomplex wing root structures, for FMAVs other solutions are possible and needed. This article providesan overview on structures and their functions in insects and the engineering alternatives. Emphasis is ontechniques which are applicable in smaller designs. In particular, control mechanisms and thorax structuresare covered. Initial concepts are analyzed and presented based onmulti-body and FE representation.
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