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Paulo Fonseca Teixeira - One of the best experts on this subject based on the ideXlab platform.
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a bayesian model to assess Rail Track geometry degradation through its life cycle
Research in Transportation Economics, 2012Co-Authors: Antonio Ramos Andrade, Paulo Fonseca TeixeiraAbstract:One of the major drawbacks in Rail Track investments is the high level of uncertainty in maintenance, renewal and unavailability costs for the Infrastructure Managers (IM) during the life-cycle of the infrastructure. Above all, Rail Track geometry degradation is responsible for the greatest part of Railway infrastructure maintenance costs. Some approaches have been tried to control the uncertainty associated with Rail Track geometry degradation at the design stage, though little progress has improved the investors' confidence. Moreover, many studies on Rail Track life-cycle cost modelling tend to forget the dynamic perspective in uncertainty assessments and do not quantify the expected reduction of the uncertainty associated with degradation parameters as more inspection data is collected after operation starts.
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a bayesian model to assess Rail Track geometry degradation through its life cycle
Research in Transportation Economics, 2012Co-Authors: Antonio Ramos Andrade, Paulo Fonseca TeixeiraAbstract:One of the major drawbacks in Rail Track investments is the high level of uncertainty in maintenance, renewal and unavailability costs for the Infrastructure Managers (IM) during the life-cycle of the infrastructure. Above all, Rail Track geometry degradation is responsible for the greatest part of Railway infrastructure maintenance costs. Some approaches have been tried to control the uncertainty associated with Rail Track geometry degradation at the design stage, though little progress has improved the investors' confidence. Moreover, many studies on Rail Track life-cycle cost modelling tend to forget the dynamic perspective in uncertainty assessments and do not quantify the expected reduction of the uncertainty associated with degradation parameters as more inspection data is collected after operation starts. In this paper, a Bayesian model to assess Rail Track geometry degradation is put forward, building up a framework to update the uncertainty in Rail Track geometry degradation throughout its life-cycle. Using inspection data from Lisbon-Oporto line, prior probability distributions are fitted to the model parameters quantifying the associated uncertainty at the design stage, and then they are sequentially updated as more inspection data becomes available when operation starts. Uncertainty reduction in geometry degradation parameters is then assessed by computing their posterior probability distributions each time an inspection takes place. Finally, the results show that at the design stage, the uncertainty associated with degradation rates is very high, but it reduces drastically as more inspection data is collected. Significant impacts on the definition of maintenance cost allocation inside Railway business models are discussed, especially for the case of Public and Private Partnerships. Moreover, potential impacts of this methodology in maintenance contracts are highlighted. For the case of a new infrastructure, it is proposed that maintenance costs assessments related to Track geometry degradation are no longer assessed at the design stage based only on the prior probability distributions of the degradation model parameters, but renegotiated instead after a ‘warm-up’ period of operation based on their posterior probability distributions.
Buddhima Indraratna - One of the best experts on this subject based on the ideXlab platform.
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Improved Performance of Ballasted Rail Track Using Geosynthetics and Rubber Shockmat
Journal of Geotechnical and Geoenvironmental Engineering, 2016Co-Authors: Sanjay Nimbalkar, Buddhima IndraratnaAbstract:AbstractLarge repetitive wheel loads from heavy haul and passenger trains can cause significant Track deformation that leads to poor Track geometry and safety issues. The inclusion of geosynthetics and rubber mats (i.e., shockmat) in critical sections in the Track for reducing these adverse effects was further examined through an extensive field trial in the town of Singleton, New South Wales (NSW), Australia. Four types of geosynthetics and a shockmat were installed below the ballast layer in selected sections of Track constructed on three different subgrades (soft alluvial clay, hard rock, and concrete bridge), and the performance of the instrumented Track was monitored for five years under in-service conditions including tamping operations. The measured stress-deformation response indicates that the geosynthetics effectively control the long-term and transient strains in the ballast layer, with the obvious benefit of reducing maintenance costs. The study also showed that the aperture size of geogrids i...
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application of shock mats in Rail Track foundation subjected to dynamic loads
Procedia Engineering, 2016Co-Authors: Sinniah K Navaratnarajah, Buddhima Indraratna, Sanjay NimbalkarAbstract:Rail Track substructure (ballast, subballast and subgrade) is the most essential component of the Railway system in view of Track stability. The ballast is the largest component of the Track substructure and it is the key load-bearing stratum packed with rock aggregates underneath and around the sleepers, thereby providing structural support against dynamic stresses caused by moving trains. However under large dynamic stresses exerted by heavy haul and high speed trains, the degradation of Track substructure including ballast becomes significant. This in turn affects the Track stability and creates frequent maintenance, thus increasing the life cycle cost of the Rail network. Therefore, mitigating degradation of the ballast layer is vital in view of Track longevity. In recent years, the use of resilient soft pads (shock mats) above the ballast (i.e. Under Sleeper Pad, USP) and below the ballast (i.e. Under Ballast Mat, UBM) has become a common practice. Many countries, including Australia have adopted the use of resilient pads in the Rail Track foundation. Currently, the studies on resilient mats are mostly limited to the reduction of vibration and noise. There is a lack of proper assessment of the geotechnical behavior of ballast when used along with shock mats. This paper provides an assessment of the triaxial behavior of the Track substructure with and without shock mats under dynamic loading condition. A numerical model was developed based on the modified stress-dilatancy approach to capture the stress-strain and volume change behavior of ballast during impact loading. Model predictions are compared with laboratory results. It was found that the shock mats provide significant advantages in terms of reduced particle breakage and enhanced Track stability.
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application of optical fiber bragg grating sensors in monitoring the Rail Track deformations
Geotechnical Testing Journal, 2015Co-Authors: Buddhima Indraratna, S Karimullah K Hussaini, Jayan S VinodAbstract:The lateral flow of ballast during the passage of trains can reduce the stability of Rail Tracks. Therefore, it is important to monitor and restrain the movement of ballast accordingly in order to prevent Track misalignment. This current study explored the use of optical-Fiber Bragg Grating (FBG) sensors to measure the lateral displacement of unreinforced and geogrid-reinforced ballast. The tests were conducted on fresh latite basalt at a loading frequency of 20 Hz and up to 250 000 load cycles. The test results showed that the FBG sensing system is fully capable of measuring the lateral displacement of ballast under high-frequency cyclic loading. A comparison of strains obtained from FBGs installed at different depths along the ballast depth is made and the lateral strain profiles are measured. Moreover, an empirical model to convert the FBG strains to an equivalent lateral displacement of ballast is proposed to effectively use this technology in real-time monitoring of Track deformations.
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performance assessment of reinforced ballasted Rail Track
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2014Co-Authors: Buddhima Indraratna, Sanjay Nimbalkar, Tim NevilleAbstract:In coastal Australia, high population density and increased traffic volumes have promoted rapid expansion of urban transportation infrastructure including Railways. Coastal soft clays pose significant construction challenges. Therefore, the search for innovative ground improvement techniques imperative for more resilient and sustainable transport infrastructure has become an obvious priority in research and development. Use of artificial inclusions such as polymeric geosynthetics and energy-absorbing shock mats is described in this paper as a suitable alternative for reducing unacceptable Track degradation and for ensuring sustainable Track alignment. An extensive monitoring programme was undertaken on fully instrumented Track sections constructed near Singleton, New South Wales, Australia. Four types of geosynthetics were installed at the ballast–capping interface of Track sections located on different types of subgrades. It was found that geogrids could decrease the vertical settlement of the ballast la...
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monitoring of ballasted Rail Track with geosynthetic reinforcement
CORE 2012 Rail - the core of integrated transport conference on railway engineering Perth Western Australia 7-10 September 2012, 2012Co-Authors: Pongpipat Anantanasakul, Sanjay Nimbalkar, Buddhima Indraratna, Tim NevilleAbstract:Large repetitive stresses induced from heavy train traffic can cause significant degradation of ballasted Rail Tracks, leading to poor Track geometry and stability. This, in turn, results in decreased Track performance and increased maintenance costs. Inclusions of geosynthetics in the Track substructure can decrease the impact of these adverse effects. Thus, understanding the effects of geosynthetic reinforcement becomes necessary for improved design procedures and construction practices for ballasted Rail Tracks. However, the complex nature of the stress-strain response of composite Track system is often difficult to assess using only laboratory tests on reduced-scale models. It is imperative to also understand this behaviour through in-situ monitoring of Rail Tracks. A series of full-scale field experiments was undertaken on Track sections near Singleton, New South Wales to investigate the effects of geosynthetic reinforcement on the performance of the Track. These experimental Track sections were built on subgrade soils with varying stiffness, and various types of geosynthetics were installed at the ballast-subballast interface. Transient and accumulated deformations of the Track substructure as well as variation of traffic-induced stresses in the Track were routinely monitored. It was found that geogrids can decrease vertical strains of the ballast with obvious benefits of reduced Track maintenance costs. It was also found that a few selected types of geogrids can be effectively used for soft subgrade soils.
Robert C Leachman - One of the best experts on this subject based on the ideXlab platform.
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using simulation modeling to assess Rail Track infrastructure in densely trafficked metropolitan areas
Winter Simulation Conference, 2002Co-Authors: Maged Dessouky, Robert C LeachmanAbstract:We present a simulation modeling methodology to assess the Rail Track infrastructure in highly dense traffic areas. We used this model to determine the best Trackage configuration to meet future demand in the Los Angeles-Inland Empire Trade Corridor Region. There are three major challenges in modeling a Rail network in a densely trafficked metropolitan area. They are: (1) complex Trackage configurations, (2) various speed limits, and (3) non-fixed dispatching timetables and routes between the origin and destination. Our proposed model has the ability to handle the above complexities in order to determine the best use of the Rail capacity. Furthermore, our methodology is general enough so that it can be applied to other large scale Rail networks.
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modeling very large scale systems using simulation modeling to assess Rail Track infrastructure in densely trafficked metropolitan areas
Winter Simulation Conference, 2002Co-Authors: Maged Dessouky, Robert C LeachmanAbstract:We present a simulation modeling methodology to assess the Rail Track infrastructure in highly dense traffic areas. We used this model to determine the best Trackage configuration to meet future demand in the Los Angeles-Inland Empire Trade Corridor Region. There are three major challenges in modeling a Rail network in a densely trafficked metropolitan area. They are: (1) complex Trackage configurations, (2) various speed limits, and (3) non-fixed dispatching timetables and routes between the origin and destination. Our proposed model has the ability to handle the above complexities in order to determine the best use of the Rail capacity. Furthermore, our methodology is general enough so that it can be applied to other large scale Rail networks.
Antonio Ramos Andrade - One of the best experts on this subject based on the ideXlab platform.
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a bayesian model to assess Rail Track geometry degradation through its life cycle
Research in Transportation Economics, 2012Co-Authors: Antonio Ramos Andrade, Paulo Fonseca TeixeiraAbstract:One of the major drawbacks in Rail Track investments is the high level of uncertainty in maintenance, renewal and unavailability costs for the Infrastructure Managers (IM) during the life-cycle of the infrastructure. Above all, Rail Track geometry degradation is responsible for the greatest part of Railway infrastructure maintenance costs. Some approaches have been tried to control the uncertainty associated with Rail Track geometry degradation at the design stage, though little progress has improved the investors' confidence. Moreover, many studies on Rail Track life-cycle cost modelling tend to forget the dynamic perspective in uncertainty assessments and do not quantify the expected reduction of the uncertainty associated with degradation parameters as more inspection data is collected after operation starts.
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a bayesian model to assess Rail Track geometry degradation through its life cycle
Research in Transportation Economics, 2012Co-Authors: Antonio Ramos Andrade, Paulo Fonseca TeixeiraAbstract:One of the major drawbacks in Rail Track investments is the high level of uncertainty in maintenance, renewal and unavailability costs for the Infrastructure Managers (IM) during the life-cycle of the infrastructure. Above all, Rail Track geometry degradation is responsible for the greatest part of Railway infrastructure maintenance costs. Some approaches have been tried to control the uncertainty associated with Rail Track geometry degradation at the design stage, though little progress has improved the investors' confidence. Moreover, many studies on Rail Track life-cycle cost modelling tend to forget the dynamic perspective in uncertainty assessments and do not quantify the expected reduction of the uncertainty associated with degradation parameters as more inspection data is collected after operation starts. In this paper, a Bayesian model to assess Rail Track geometry degradation is put forward, building up a framework to update the uncertainty in Rail Track geometry degradation throughout its life-cycle. Using inspection data from Lisbon-Oporto line, prior probability distributions are fitted to the model parameters quantifying the associated uncertainty at the design stage, and then they are sequentially updated as more inspection data becomes available when operation starts. Uncertainty reduction in geometry degradation parameters is then assessed by computing their posterior probability distributions each time an inspection takes place. Finally, the results show that at the design stage, the uncertainty associated with degradation rates is very high, but it reduces drastically as more inspection data is collected. Significant impacts on the definition of maintenance cost allocation inside Railway business models are discussed, especially for the case of Public and Private Partnerships. Moreover, potential impacts of this methodology in maintenance contracts are highlighted. For the case of a new infrastructure, it is proposed that maintenance costs assessments related to Track geometry degradation are no longer assessed at the design stage based only on the prior probability distributions of the degradation model parameters, but renegotiated instead after a ‘warm-up’ period of operation based on their posterior probability distributions.
Sharath Pankanti - One of the best experts on this subject based on the ideXlab platform.
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Rail Component Detection, Optimization, and Assessment for Automatic Rail Track Inspection
IEEE Transactions on Intelligent Transportation Systems, 2014Co-Authors: Ying Li, Hoang Trinh, Norman Haas, Charles Otto, Sharath PankantiAbstract:In this paper, we present a real-time automatic vision-based Rail inspection system, which performs inspections at 16 km/h with a frame rate of 20 fps. The system robustly detects important Rail components such as ties, tie plates, and anchors, with high accuracy and efficiency. To achieve this goal, we first develop a set of image and video analytics and then propose a novel global optimization framework to combine evidence from multiple cameras, Global Positioning System, and distance measurement instrument to further improve the detection performance. Moreover, as the anchor is an important type of Rail fastener, we have thus advanced the effort to detect anchor exceptions, which includes assessing the anchor conditions at the tie level and identifying anchor pattern exceptions at the compliance level. Quantitative analysis performed on a large video data set captured with different Track and lighting conditions, as well as on a real-time field test, has demonstrated very encouraging performance on both Rail component detection and anchor exception detection. Specifically, an average of 94.67% precision and 93% recall rate has been achieved for detecting all three Rail components, and a 100% detection rate is achieved for compliance-level anchor exception with three false positives per hour. To our best knowledge, our system is the first to address and solve both component and exception detection problems in this Rail inspection area.
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enhanced Rail component detection and consolidation for Rail Track inspection
Workshop on Applications of Computer Vision, 2012Co-Authors: Hoang Trinh, Norman Haas, Charles Otto, Sharath PankantiAbstract:For safety purposes, Railroad Tracks need to be inspected on a regular basis for physical defects or design noncompliances. Such Track defects and non-compliances, if not detected in a timely manner, may eventually lead to grave consequences such as train deRailments. In this paper, we present a real-time automatic vision-based Rail inspection system, with main focus on anchors - an important Rail component type, and anchor-related Rail defects, or exceptions. Our system robustly detects important Rail components including ties, tie plates, anchors with high accuracy and efficiency. Detected objects are then consolidated across video frames and across camera views to map to physical Rail objects, by combining the video data streams from all camera views with GPS information and speed information from the distance measuring instrument (DMI). After these Rail components are detected and consolidated, further data integration and analysis is followed to detect sequence-level Track defects, or exceptions. Quantitative analysis performed on a real online field test conducted on different Track conditions demonstrates that our system achieves very promising performance in terms of Rail component detection, anchor condition assessment, and compliance-level exception detection. We also show that our system outperforms another advanced Rail inspection system in anchor detection.
