| 1. |
- Patra, Ambika Prasad, et al.
(författare)
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Assessment and improvement of railway track safety
- 2009
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Ingår i: Special issue on heavy haul and innovative development. - Los Angeles : Sage Publications, Incorporated. ; , s. 91-98
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Konferensbidrag (refereegranskat)abstract
- In this paper, an approach has been developed to assess safety of the railway track by estimating the probability of derailment. Models for probability of derailment are developed based on undetected rail breaks and poor track quality using Petri-Nets and Monte Carlo simulations. The Effect of inspection intervals on lowering the probability has been analysed. The performance of the model is illustrated by an example from a track section of the iron ore line of Banverket (Swedish National Rail Administration).
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| 2. |
- Patra, Ambika Prasad, et al.
(författare)
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Availability analysis of railway track circuits
- 2010
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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. ; 224:3, s. 169-177
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Tidskriftsartikel (refereegranskat)abstract
- Railways are expected to operate with ever increasing availability. The availability of railway systems and subsystems influences the overall operational availability. As the track circuit is a key component of railway signalling and control, it can contribute significantly to the loss of availability of the railway system. One way to increase the availability of the track circuit is by implementing a proper maintenance policy. In this article, Petri-nets have been used to develop models for availability analysis of the track circuit for both time-based and condition-based maintenance. A sensitivity analysis has been performed to estimate the effect of maintenance parameters on availability performance using cost-benefit analysis.
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| 3. |
- Patra, Ambika Prasad, et al.
(författare)
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Availability target of the railway infrastructure : an analysis
- 2010
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Ingår i: 2010 proceedings. - Piscataway, NJ : IEEE Communications Society. - 9781424451029
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Konferensbidrag (refereegranskat)abstract
- The railway has been accepted as one of the most environmentally friendly modes of transport for goods and passengers. However, the railway sector is striving to increase its capacity to meet the growing demand for the transport of goods and passengers with a high level of punctuality in its services. Higher availability requires the effective operation and maintenance of infrastructure, often necessitating the implementation of cost-effective preventive maintenance strategies. Therefore, a higher availability target means higher maintenance investment. However, the question of setting the availability target for the infrastructure is not easy, as it involves many influencing decision parameters, apart from a good understanding of the network configuration and traffic density. Railway networks that have a smaller number of trains and a low punctuality requirement do not require higher availability targets. The aim of this paper is to estimate the availability target for railway infrastructure based on the capacity and punctuality requirements of infrastructure managers and train operating companies. The objectives of the paper are to develop an approach to i) estimating the capacity of the infrastructure based on the design and operational characteristics and evaluating the influence of infrastructure availability on the required capacity and ii) estimating the volume of primary and secondary delay due to failures and maintenance of the infrastructure and establishing the relationship between availability and punctuality requirements. To achieve these objectives, an example is presented with parameters drawn from failure, maintenance and traffic data. Finally, a model has been developed in Petri-Nets to establish a relationship between availability, capacity and punctuality. Monte Carlo simulation is used to establish the relationship. The simulation results illustrate the effect of infrastructure availability on train delays and capacity.
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| 4. |
- Patra, Ambika Prasad, et al.
(författare)
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Cost Effective Maintenance Policy: A Case Study
- 2010
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Ingår i: International Journal of Performability Engineering. - India : RAMS Consultants. - 0973-1318. ; 6:6, s. 595-603
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Tidskriftsartikel (refereegranskat)abstract
- The European Rail Traffic Management System (ERTMS) is a major venture initiated by the European Union in order to create an interoperable railway network within Europe. The manufacturers of the ERTMS strive to attain a competitive edge by demonstrating the efficiency of their systems. Achieving the optimal cost effectiveness is one of the significant ways to address the efficiency of the system and involves maximising the availability and minimising the life cycle cost of the system over the system life cycle. One of the important ways of maximising the cost effectiveness of the system is to optimise the maintenance policy. This paper demonstrates the estimation of the cost effectiveness of an ERTMS system. The degradation and repair process of the system is modelled by Petri-Nets. Failure, maintenance and cost data are used as parameters for the model. The model will be useful for systems that experience degradations and are subjected to imperfect maintenance.
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| 5. |
- Patra, Ambika Prasad, et al.
(författare)
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Failure prediction of rail considering rolling contact fatigue
- 2010
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Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 17:3, s. 167-177
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Tidskriftsartikel (refereegranskat)abstract
- Rolling Contact Fatigue (RCF) is a major cause of rail failure leading to replacement of rails. RCF defects are caused by a combination of high normal and tangential stresses between the wheel and rail. In this study, a methodology has been proposed to evaluate P-F (Potential failure-functional failure) interval of RCF defects based on RCF defect rate distribution and fatigue design life distribution. For estimating fatigue design life distribution, load under variable amplitude has been considered which is a case in the mixed traffic scenario. Stochastic S-N curve has been considered to account for probabilistic nature of fatigue life. The stress history can be calculated from the actual load history. RCF defect distribution can be estimated from the probability density function of the defects from the actual field data. The proper estimation of P-F interval will help the infrastructure managers to define rail inspection interval scientifically.
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| 6. |
- Patra, Ambika Prasad, et al.
(författare)
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Life cycle cost estimation of railway track sytem
- 2006
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Ingår i: Condition Monitoring and Diagnostic Engineering Management. - Luleå : Luleå tekniska universitet. - 9789163188060 ; , s. 659-666
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Konferensbidrag (refereegranskat)abstract
- Railway track is the most maintained component in any rail infrastructure. Study shows a lot of money has been spent annually for better maintenance of track world wide and eventually Life Cycle Cost for the track goes very high. Manufacturers and service providers for the track system are trying hard to bring down the LCC cost and at the same time keeping the risk involved to it as low as possible. It has been seen that maintenance and operation cost always takes a major share of any LCC analysis. In this paper the authors have attempted to describe the methods to reduce the operation and maintenance cost and hence optimise the LCC with low risk involved. Railway track system consists of major components like rail, turnout, crosstie etc. Each part needs equal attention in terms of maintenance and cost. In a broad sense low maintenance and operation cost always accounts for high reliability, proper maintenance planning and scheduling, proper main power allocation and low spare part cost. The current paper focuses on finding methods to life period determination of the track, proper scheduling of preventive maintenance/overhauling, man power allocation for maintenance, spare parts quantity determination for all the major parts of the railway track system. Eventually the authors have tried to develop software which will determine the above mentioned parameters and hence calculate the Life Cycle Cost for the track system. The software will also help in determining the critical component(s) in the track system which need(s) more attention as far as LCC is concerned.
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| 7. |
- Patra, Ambika Prasad, et al.
(författare)
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Life cycle cost of railway track : an overview
- 2007
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Ingår i: 20th international congress on condition monitoring and diagnostic engineering management : COMADEM 2007. - Coimbra : IT - Instituto de Telecommunicações. - 9789898109026 ; , s. 407-416
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Konferensbidrag (refereegranskat)abstract
- Several cost models have been used in the field of railway infrastructure over the years, but the usage of LCC (Life Cycle Cost) in infrastructure is quite limited. These cost models while taking decisions on maintenance and renewal actions rarely consider the whole life cycle perspective of the infrastructure. The important aspect of life cycle costing is to understand the factors that influence the LCC and the parameters that are needed to estimate it. This paper discusses the need of LCC for railway infrastructure and the current models in practice. It also discusses the cost model being followed at the Swedish National Rail Administration (Banverket) for its new investment and upgrading projects. Finally, a process for life cycle costing estimation is illustrated.
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| 8. |
- Patra, Ambika Prasad
(författare)
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Maintenance decision support models for railway infrastructure using RAMS & LCC analyses
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today's railway sector is imposing high demands for service quality on railway infrastructure managers. Since railway infrastructure has a long asset life, it requires efficient maintenance planning to perform effectively throughout its life cycle to meet these high demands. Traditionally maintenance decisions for the railway infrastructure have been based on past experience and expert estimations. The application of RAMS (Reliability, Availability, Maintainability and Safety) analysis for railway infrastructure is limited. The focus of this thesis is to demonstrate the applicability of RAMS analysis in effective maintenance planning. Within the scope of this research, various case studies associated with Banverket (the Swedish National Rail Administration and ALSTOM Transport have been carried out. The research presents approaches and models for estimating RAMS targets based on the service quality requirements of the railway infrastructure. The availability target of the infrastructure has been estimated by considering the capacity and punctuality requirements of the infrastructure, whereas the safety goal of the track has been estimated by calculating the probability of derailment by means of undetected rail breaks and poor track quality. Effective estimation of the RAMS targets will help infrastructure managers to predict the maintenance investment in the railway infrastructure needed over a period of time in order to achieve the targets. Nevertheless, the availability target of the infrastructure can lead to train delay. A model has been developed to achieve the availability target in both the scheduled and the condition based maintenance regimes by choosing an effective maintenance interval and detection probability respectively. This has been illustrated by a case study on track circuits. Different maintenance strategies can help in achieving the RAMS targets. In order to determine the cost-effective solution, LCC (life cycle cost) should be used. The maintenance strategy with lowest LCC will be the cost effective maintenance strategy. This has been demonstrated by a case study on a signalling system. Sensitivity analyses have been performed to calculate the maximum cost effectiveness of the system for different maintenance parameters. LCC estimation for a maintenance strategy should always consider the risks associated with the strategy. A fair degree of uncertainty is also associated with LCC estimation due to the statistical characteristics of RAMS parameters. An approach has been developed in this thesis to calculate the uncertainties associated with LCC estimation. Petri-Net analyses, Monte Carlo simulations, Design of Experiment have been used to develop models to achieve the objectives of this thesis. This thesis discusses the applicability of RAMS and LCC analyses for railway infrastructure and demonstrates models for effective infrastructure maintenance planning.
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| 9. |
- Patra, Ambika Prasad
(författare)
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RAMS and LCC in rail track maintenance
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Railway infrastructure is a complex system. An important aspect of the rail infrastructure is that the assets have a long useful life. So once installed, it is very difficult to modify the initial design. Thus, the performance of the infrastructure depends on the maintenance and renewal decisions taken during its life cycle. In many countries, restructuring railways and increasing efficiency requirements cause a changing environment for infrastructure management. Responsibilities for parts of the railway system are often handed over to different players. In order to guarantee optimal long-term results for the railway systems, the effects of decision should be systematically evaluated. The infrastructure manager, responsible for design, construction, maintenance, renewal and upgrading the infrastructure, has a clearly defined role and is confronted by increasing performance of the associated partners. Due to increase in operation and maintenance costs, infrastructure managers are compelled to optimise budget, while reliability and availability have to be increased without endangering the traffic safety. A systematic approach is needed by the infrastructure manager for guaranteeing defined levels of performance. As in the current scenario, most of the maintenance and renewal decisions are based on past experience and expert estimations, a need for Life cycle cost (LCC) approach arises. A life cycle costing approach considering Reliability, Availability, Maintainability & Safety (RAMS) analysis will provide a way to optimise the maintenance strategy, considering the short term budget requirements as well as long term costs of ownership. To achieve overall RAMS and LCC objectives of the system, it is important to follow systematic RAMS/ LCC actions through out the life cycle of the system. One of the important phases of the track system life cycle is the operation and maintenance phase due to its long phase life where RAMS and LCC are to be optimised. The aim of this thesis is to develop an approach for making effective maintenance decisions based on RAMS and LCC analysis. The thesis looks into three aspects of RAMS and LCC analysis, i.e. defining RAMS and LCC in track maintenance context, applicability of RAMS and LCC in maintenance planning of track and uncertainty associated with LCC due to RAMS parameters. The thesis provides an approach for an effective RAMS and LCC analysis during operation and maintenance phase. The thesis also comprises of the state-of-the-art of RAMS and LCC analysis followed by infrastructure managers and railway manufacturers in Europe. This work has been done as a part of a European project. To realise the benefits of large investments on railway infrastructure, effective maintenance is required. An approach has been developed on how RAMS and LCC facilitates in taking effective maintenance decisions. An integrated maintenance management system along with RAMS management system and LCC management system is must for arriving at the correct decisions. The LCC modelling followed by Banverket (Swedish National Rail Administration) for re-investment and upgrading projects have been described. While taking decisions of maintenance on the track based and RAMS and LCC, uncertainty associated with LCC should be considered. The research presents the uncertainty associated with LCC estimation and defines an approach to calculate uncertainty in LCC estimation due to RAMS parameters. A case was study carried out on iron ore line (Malmbanan) that runs from Luleå to Narvik. The RAMS data were collected from different Banverket's databases. The study helps in calculating uncertainty associated with LCC and thereby act as a decision support tool for effective track maintenance.
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| 10. |
- Patra, Ambika Prasad, et al.
(författare)
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Reliability prediction for rail considering rolling contact fatigue
- 2009
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Konferensbidrag (refereegranskat)abstract
- Rolling Contact Fatigue (RCF) is a major cause of rail replacement for infrastructure managers. RCF defects are caused by a combination of high normal and tangential stresses between the wheel and rail. In this study, a methodology has been proposed to evaluate P-F (Potential failure-functional failure) interval of RCF defects based on RCF defect rate distribution and fatigue design life distribution. For estimating fatigue design life distribution, load under variable amplitude has been considered which is a case in the mixed traffic scenario. Stochastic S-N curve has been considered to account for probabilistic nature of fatigue life. The stress history can be calculated from the actual load history. RCF defect distribution can be estimated from the probability density function of the defects from the actual field data. The proper estimation of P-F interval will help the infrastructure managers to define rail inspection interval scientifically.
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