Reliability, Availability, Maintainability And Safety Research Articles

Monitoring Scheme for Safety Hazard Status of Urban Rail Transit Operation Equipment and Facilities Based on Blockchain Technology

Urban rail transit plays a very important role in cities’ social and economic development. To ensure the safe and stable operation of urban rail transit operation equipment and facilities, it is necessary to monitor a large number of safety hazard statuses and data and improve the over-centralisation of traditional monitoring. This paper designs a scheme for storing, validating and monitoring the safety hazard status of urban rail transit operation equipment and facilities based on blockchain technology. The safety hazards of equipment and facilities during the operation stage of urban rail transit are listed using the literature analysis method and the case study method. The European RAMS (reliability, availability, maintainability and safety) standard method is used to determine the safety hazard status of equipment and facilities by availability index. Based on the features of the consensus mechanism, smart contract and other features of blockchain technology, this paper designs an overall scheme for storing, verifying and monitoring the safety hazard status of equipment and facilities. This scheme provides a practical operation method for evaluating the safety hazard status of rail transit equipment and facilities, which is conducive to the safety rectification of the entire urban rail transit.

Meta heuristic intelligent decision support model for uncertainty estimation of life cycle cost in railways rolling stock

In Railways rolling stock, Rate of Occurrence of Failures (ROCOF) of repairable components is time varying and has a failure trend, so the combined process of Reliability, Availability, Maintainability and Safety (RAMS) with Life Cycle Cost (LCC) is a stochastic process. Heuristic approaches have been used to design intelligent decision support model to reduce Life Cycle Cost (LCC) and to manage Maintainability to achieve the required Reliability. As heuristic approaches have major drawback of inability to combine both the exploration and exploitation capabilities to reach all regions in the search space, so we propose Meta heuristic approach by hybridization Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). Experimental study proves that our proposed approach significantly avoids this drawback and outperforms the traditional heuristic approaches in reducing LCC while properly maintains the required reliability.

Safety enhancement design method and control strategy for CCU of high-speed train

The Train Control and Monitoring System (TCMS) is the communication command center of the train, and the Central Control Unit (CCU) is its core component, which should achieve SIL4 safety integrity level defined in standard EN50129. Comparing the current CCU safety mode of dual-machine hot standby to the double 2 out of 2 (2oo2) structure, this paper find that the latter performances better in security. So a new CCU architecture with enhanced safety is proposed, the double 2oo2 structure is applied to the CCU design, and the Markov failure probability model is established to analyze its safety quantitatively. The CCU based on double 2oo2 redundant structure could meet the failure safety principle of composite fail-safety and reactive fail-safety stipulated in the SIL4 safety integrity level, and its Tolerable Functional Failure Rate (TFFR) could reach the requirements of the SIL4. As another important part of RAMS (Reliability, Availability, Maintainability, and Safety), the reliability of this CCU architecture is evaluated both qualitatively and quantitively. According to the results, the double 2oo2 structure could greatly improve the safety of the TCMS and can be used in railway signal system with SIL4 safety integrity requirements.

An Alternative Approach to Railway RAMS: Development of an Extended RAMS Framework

The management of a diverse asset portfolio is a demanding task for railway asset managers. They must ensure that the network delivers a high level of performance for customers and adheres to safety limits. Reliability, availability, maintainability and safety (RAMS) analysis is regularly used to assess the performance of systems, including railway networks. However, currently there are a wide range of different approaches to RAMS analysis in the railway industry. This research seeks to identify and consolidate any potential extensions to the traditional RAMS approach into a single framework: extended RAMS. The framework comprises ten parameters, RAMS and six additional parameters of particular interest to railway asset managers, including capacity and train performance. The framework is intended for use by asset managers to evaluate the attributes and current status of the railway infrastructure and enable comparison between different parts of the network and to evaluate different stakeholder needs.

An alternative approach to railway asset management value analysis: application to a UK railway corridor

Railway networks are complex systems, and the management of such systems is a challenging task for railway asset managers. It is their responsibility to ensure that the network delivers the highest level of performance for all stakeholders while adhering to strict safety regulations and financial constraints. Historically, reliability, availability, maintainability and safety (RAMS) analysis has been used to assess the performance and safety of railway networks. Nonetheless, there is a lack of consistency in approaches across the industry, with analysis often influenced by the key stakeholders at the time. This research demonstrates an application of an extended RAMS (ExRAMS) framework on the UK railway network. The ExRAMS framework aims to consolidate various extensions to the traditional RAMS approach into a single universal approach, which is beneficial to all stakeholders. This paper explores the data currently available within the rail industry and how these can be used to assess the ten metrics within the framework. The final part of the paper explores how the parameters within the ExRAMS framework can be used as the bases of a value analysis, which can then be used to assist with asset-management decisions.

Combining RAMS with EEP for performance-based maintenance: a review

PurposeThe study aims to perform an extensive literature review in the area of the maintenance decision analysis (MDA), especially in power generation systems. In the basis of this review, the paper proposes a new model for the MDA which involves a combination of reliability, availability, maintainability and safety (RAMS) performance with energy efficiency performance (EEP).Design/methodology/approachStarting from the opportunity in Sustainable Development Scenario (SDS) by improving the energy efficiency (EE) and using renewable energy for the power generation system, also concerning to the major challenge of maintenance optimization in order to implement maintenance strategy, the maintenance decision-making and energetic efficiency management system (EEMS) have been reviewed. In the context of power generation system's performance, the measurement is also analyzed and identified. Then, the extensive literature review has been performed to compare between RAMS and EEP. And finally, the limitation and gap, where EEP is not yet a complementary consideration during MDA being identified and a new model for the performance-based MDA is proposed.FindingsThe new model proposed for the performance-based MDA is able to be used to conduct maintenance decision by utilizing the combination of RAMS and EEP depending on the type of decision required.Practical implicationsThere is an opportunity for a maintenance organization of power generation plant to apply this new model proposed for the MDA in order to optimize the maintenance scope and schedule.Originality/valueThe result of work in this paper forms the basis for combining RAMS with EEP as performance-based MDA tools in the context of maintenance of the power generation system.

A Review Study on Assessing the Sustainability of Design and Maintenance of Slab Track Systems for Turkey

Many companies provide different slab track products and solutions. Various types of these are used in Japan, Europe and North America. The utilization of slab track benefits railway operators in terms of RAMS (reliability, availability, maintainability and safety) as well as the life cycle cost despite its high initial cost. In Japan, the maintenance cost of slab track is 25% of the maintenance cost of ballasted track. In addition, recent surveys show that the construction costs of slab track are 30% to 50% higher than the construction cost of standard ballasted track.

Performance assessment analysis of UHF machines using Reliability, Availability, Maintainability and Safety (RAMS) analysis methods

XYZ Company is manufacturing engaged in the rubber industry located in the city of Bandung, because economic growth and demand from consumers are increasing, making companies demanded to meet the target orders promptly. One way to minimize losses and the possibilities that must be borne by the company is to increase Reliability, Availability, Maintainability of the production and the safety value. Data in the form of Mean Downtime, Mean Time to Failure, Mean Time to Repair is useful for system performance that works. MTTF data can be used to assess safety systems found in PT XYZ with the safety standards of IEC 61508 using Safety Integrity Level. From the results of processing RAMS data using Reliability Block Diagram modeling based on the analytical approach, for 120 hours, the system has a Reliability value (91.12%). The average value of system Maintainability at t = 2 hours is 100%. The Inherent Availability value is 99,981% and the Operational Availability value is 99,980%. Based on the world-class maintenance Key Performace Indicator, leading and lagging availability indicators have reached the indicator target standard. Safety Integrity Level values from calculations based on PFD and RRF values of each system are in SIL 1.

Hazard Rate Estimation for GNSS‐Based Train Localization Using Model‐Based Approach

GNSS (Global navigation satellite system) has shown its ability on the non-safety relevant applications in various applications. In railway domain, safety is the utmost concern, GNSS-based train localization unit is the carrier of safe localization. EN 50126 standard specifies the electric and electronic system performance requirements as Reliability, availability, maintainability and safety (RAMS). Safety performance characteristic is based on the reliability and availability analysis results. The formal method considering the risk identification and analysis is compulsory for the safety assessment. This paper provides the method for hazard analysis of the GNSS-based train localization function and further the hazard rate estimation of each hazard. The model-based approach using GNSS localization unit working principle is proposed to study railway localization behavior features. The hazard for the localization unit is formally stated, real collected data on circular test track in Beijing is studied using the proposed method. The result shows that the safety requirement of the performance can be transformed into safety integrity properly, the risks of GNSS in train station environment conditions are presented.

Reliability, availability and maintainability analyses for railway infrastructure management

Reliable, available, maintainable and safe operation in railway transportation is significant for passenger and freight transportation. For these reasons, European Union put into practice a standard in 1999 known as EN 50126 to prevent railway accidents and to ensure a high level of safety in railway operations. The EN 50126 standard consists of these following concepts: Reliability, Availability, Maintainability and Safety (RAMS). These concepts are also recognised as RAMS analyses, which enable to do risk analyses to minimise the risks to the acceptable levels. In this study, a model framework including some stages was developed and the Reliability, Availability and Maintainability (RAM) analyses were applied to the railway infrastructure management. In addition, a case study was analysed for Uzbekistan high-speed railways between Tashkent and Sirdaryo train stations. The RAM analysis techniques were used during the analysis stages. The analyses were performed for the track geometry and the each type of railway track components to achieve a reliable, available and maintainable railway infrastructure management.

Integrating Ergonomics in Maintanability:A Case Study from Manufacturing Industry

Maintainability is key part of Reliability, Availability, Maintainability and Safety (RAMS) estimation and prediction in complex assets. Indeed, availability calculation comprises accurate estimati ...

IT System for Supporting Cost-Reliability Analysis of Fleet Vehicles

Abstract The paper presents the technical aspects of a development of a monitoring system (ISM – Monitoring Information System) allowing a collection, processing and analysis of reliability and cost-related data of the operation of a fleet of vehicles. The platform allows performing advanced analyses according to the LCC (Life Cycle Costing) concept and IRIS compliant RAMS (Reliability, Availability, Maintainability and Safety) methodology. The tool has been developed within the research project titled ‘Increase in the efficiency of the means of public transport following the implementation of the IRIS (International Railway Industry Standard) compliant LCC and RAMS concepts based on an integrated information system’. Thanks to the implementation of the ISM system in the practices of a fleet provider, it is possible to monitor malfunction data (in RAMS indexes, life cycle costs, identification of cost-generating components) and perform multidimensional analyses on the collected historical data related to the operation of vehicles. The presented results have been obtained within the research project number PBS3/B6/30/2015 [1].

Preliminary reliability and safety assessment methodology for trans-atmospheric transportation systems

PurposeThis paper aims to propose a methodology for a safety and reliability assessment for the conceptual and preliminary design of very complex and disrupting innovative systems like trans-atmospheric vehicles. The proposed methodology differs from existing ones because it does not rely on statistical data at aircraft-level but exploits the statistical population at components-level only. For the sake of clarity, the paper provides some preliminary results of the application of the methodology at system level. The example deals with the safety and reliability assessment of a very complex propulsion system aimed at guaranteeing vertical take-off and landing capabilities of a suborbital vehicle.Design/methodology/approachThe proposed methodology is strongly based on a systems engineering approach. It exploits safety and reliability assessment analyses which have already been developed in both aeronautical and space engineering domains, but it combines them in an innovative way to overcome the lack of statistics at aircraft level. The methodology consists of two different steps: a qualitative top-down process, allowing a functional and physical decomposition of the transportation system and a following quantitative bottom-up approach, which provides the estimation of system-level reliability and safety characteristics starting from the statistical estimation of the components’ characteristics.FindingsThe paper presents a new methodology for the preliminary reliability and safety assessment of innovative transportation systems, such as hypersonic transportation systems. The envisaged methodology will overcome the poorness of statistical data that is usually affecting the conceptual design of breakthrough systems.Research limitations/implicationsThe paper shows the application of the articulated methodology to a limited case study. A complete example of application of the methodology to estimate safety and reliability characteristics at vehicle level will be provided in feature works.Practical implicationsThe methodology has been proposed to be exploited in international research activities in the field of hypersonic transportation systems. Furthermore, a massive application of this approach would allow to create a database for the generation and the update of semi-empirical models focused on high-level estimations of reliability, availability, maintainability and safety (RAMS) characteristics. Moreover, the proposed safety assessment has been conceived to be fully integrated within a typical conceptual design process.Originality/valueThe existing literature about safety and reliability assessment at the early design stages proposes pure statistical approaches which are usually not applicable to highly innovative products, where the statistical population is not existing, for example, in the case of trans-atmospheric vehicles. This paper describes how to overcome this problem, through the exploitation of statistical data at components-level only through the combination of these data to estimate RAMS characteristics at aircraft-level thanks to functional analysis, concept of operations and typical safety assessment tools, like functional hazard analysis, failure mode and effect analysis, reliability block diagram and fault tree analysis.

Model calculations of posterior reliability indicators for the proposal of the maintenance system

Designing the content and scale of maintenance of machines and equipment by a priori and posterior reliability methods in considered crucial to reducing the cost of the machine's life cycle, maintaining high operational readiness and reducing the consequences of failures. In the presented paper, attention is paid to the analysis of the calculation methods of posterior reliability for calculation indicators of reliability and to the use of the specified Weibull model for reliability calculations. The obtained results are further developed for models of optimal process calculations to perform scheduled maintenance interventions. Calculations of the other RAMS (reliability, availability, maintainability and safety) indicators that are critical to the design of an optimal engineering design with regard to maintenance and which do not receive sufficient attention in technical practice are also assessed.

Power supply of trams in Poland – current state and perspectives of development

Sustainable development of agglomerations requires efficient and ecological transport systems, i.e. electrified transport. In order to achieve the required results of operation of electrified urban transport, especially energy efficiency, it is required to closely examine the existing power supply systems. The biggest share of urban traction systems in Poland belongs to tram systems (in 15 agglomerations and cities). Recent years have witnessed an increased interest in modernisation of the existing lines and construction of new ones. Enhancement of RAMS (Reliability, Availability, Maintainability, and Safety) and energy efficiency of supply systems is a necessary requirement, due to fact that new, modern tram rolling stock with higher power poses significant challenge for the existing, in many systems, old power supply infrastructure. Furthermore, due to low driving-range of autonomous vehicles equipped with batteries and a need of frequent charging of storage devices, catenary supplied urban transport will dominate in the areas of its use. In addition, it might be helpful in developing hybrid vehicles supplied both from a catenary and from energy storage devices (charged during run under catenary) on sections without catenary. The paper presents parameters characterizing tram power supply systems in Poland. The analyses carried out for many tram lines have shown that even at relatively low investments for modernisation of the tram power supply system, it is possible to obtain fast return (energy saving due to improvement of efficiency of recuperation and the resulting reduction of CO2emission). Other advantages of modernisations include: enhancement of standards in supply of modern trams with higher power and improvement of reliability due to the reduced risk of disturbances and damages.

RAMS analysis of railway vehicles’ lifecycle

Abstract The presented paper investigates the issues concerned with the RAMS analysis with the reference to the railway means of transport. The RAMS analysis includes the quantitative and qualitative indicators of degree, that the system and its components will meet all the assumed functions preserving the requirements of the availability and safety. RAMS is a long-term process, resulted from the applied tools and techniques throughout the life cycle of railway means of transport. The overall guidelines related to the development of RAMS features are included in PN-EN 50126 Railway Applications - The Specification and Demonstration of Reliability, Availability, Maintainability and Safety (RAMS).

Climate Change Adaptation for GeoRisks Mitigation of Railway Turnout Systems

To enhance rail operational flexibility, railway turnouts are special track systems, which are designed to divert or change a train from a particular direction or a particular track onto other directions or other tracks. In reality, the railway turnout is commonly built on complex track geometry and graded terrain, which makes it one of the most unique and critical railway infrastructures. The physical constraints and complexity of turnout systems cause various risks and uncertainty in rail operations. This study critically analyses emerging geotechnical risks on turnout systems considering all aspects that can potentially result in impaired reliability, availability, maintainability and safety (RAMS) of the turnout systems. The annual derailment incidents have been evaluated to identify emerging risk factors. Not only do these incidents yield operational downtime and financial losses, but they also give rise to the casualties and sometimes the loss of lives across the world. In particular, the climate change risks on geotechnical aspects of the turnout systems have been highlighted. This paper thus presents how turnout components work as a system, the diversity of emerging risks considering natural hazards and global warming potential to the system. In addition, it highlights the climate change adaptation strategies for georisk mitigation of the railway turnout systems in order to improve RAMS of the railway turnouts and crossings, focusing on trackbed failures on the systems.

Developing a life cycle cost model for real-time condition monitoring in railways under uncertainty

The Shanghai Transport Committee has estimated that passenger traffic increased fivefold between 2005 and 2014, and will continue to increase. At the same time, the maintenance costs of the Shanghai Metro have increased to about six times their original value. To ensure reliability, availability, maintainability and safety (RAMS) in railways, equipment sometimes needs to be upgraded; new technology is an effective way of modernizing the system. Condition monitoring techniques are considered to be a pragmatic approach to improve RAMS in railways. Bearings are seen to be a key factor in the successful operation of railways, as their performance is related to safety and reliability. To meet the safety requirements, an efficient method is to implement a real-time condition monitoring (RTCM) technique. To evaluate the economic cost of this investment in RTCM, the life cycle cost (LCC) should be considered. A Petri net combined with the Monte Carlo method is used to simulate the LCC evaluation process and a case study of how to employ this method is presented.

Economic viability analysis for icing blades detection in wind turbines

Reliability, availability, maintainability and safety (RAMS) of wind turbines in cold climates are closely related to ice accretion. The deterioration of RAMS of the wind turbines involves costs such as Operation and Maintenance costs and energy losses. Systems to monitor the condition of the wind turbines play a key role in the wind energy industry to decrease the costs mentioned above and to improve the maintenance management. This research presents an economic study of the life cycle cost (LCC) for ice condition monitoring systems in wind turbines. In particular, the paper studies the economic feasibility of different commercial ice detection systems through a LCC model when wind turbines are exposed to different scenarios. To date, the scientific literature does not collect any study about the LCC for ice detection systems using different annual rates of return, and providing a map with numerical solution. The study is extended by including a bank loan for a real point of view. The findings of this study reveal the ice detection systems that are more profitable and the selection criteria to decide the use of a bank loan. Finally, it is shown that predictive costs are much smaller than corrective cost reaching a reduction of these corrective costs with the ice detection systems.

Vibration-based tools for the optimisation of large-scale industrial wind turbine devices

Wind turbine (WT) maintenance management must be in continuous improvement to develop reliability, availability, maintainability and safety (RAMS) programmes and to achieve time and cost reductions in large-scale industrial wind turbines. The optimisation of the operation reliability involves supervisory control and data acquisition to guarantee the correct levels of RAMS. A fault detection and diagnosis methodology (FDD) is proposed for the mechanical devices of a WT. The method applies the wavelet and Fourier analysis to vibration signals. The signals collected contain information on failures found in the gearbox-generator set. The information is initially tested by the fast Fourier transform (FFT) to ensure its accuracy. Then, a pattern is created based on energies that relate each failure to different frequency bands. This pattern uses the wavelet transform as the main technique. A number of turbines of the same type were instrumented in the same wind farm. The data collected from the individual turbines was fused together and analysed in order to determine the overall performance. It is expected that data fusion allows for a significant improvement, since the information gained from various condition monitoring systems can be enhanced. The paper will also focus on the application of dependable, embedded computer systems for a reliable implementation.