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, No 2
  
  • Editorial
    Editorial
    Krishna B. Misra
    2009, 5(2): 101.  doi:10.23940/ijpe.09.2.p101.mag
    Abstract   
    Related Articles

    Transportation systems are lifelines of a nation. These are physical systems that are vital for the health, safety, comfort, and economic activities and prosperity of a nation. Any complete or partial impairment of these can have a major impact on economic productivity as well as making peoples' daily lives and livelihood more difficult. These are critical systems required for moving people and material to locations distributed geographically. Therefore, we decided to have International Journal of Performability Engineering (IJPE) devote its issues occasionally to the important and critical aspects of these systems. We start this task with the discussion of reliability and safety of railway systems and eventually, we will cover aviation, shipping and road transportation problems in subsequent issues of IJPE.

    Railway system reliability and maintenance not only ensures safety and track performance but also can reduce the operational costs, improves equipment effectiveness, and eventually the performance of a railway infrastructure. This leads to control the loss of revenue and unexpected costs due to breakdowns and accidents. Railway industry is compelled to reduce wastages, improve quality and maximize infrastructure effectiveness. Benchmarking is commonly used as an effective tool in continuous improvement of the operations of railways. It helps in developing realistic goals, strategic targets and facilitates in achievement of excellence in operation and maintenance.

    In the first paper of this issue, the author tries to develop indicators related to the availability of railway system so that the losses to the stakeholders are minimal. Most of the availability indicators are calculated based on punctuality or on capacity. The train traffic controllers work on the basis of timetable and get inputs from train drivers, infrastructure personnel and the train positioning system. The timetable establishes a trade-off between traffic and track works such as preventive maintenance. When some non-planned event occurs, the controllers can make trade-offs, utilizing different recovery strategies, such as terminating trains prior to their timetabled terminus or delaying trains in order to lower total delays.

    In the second paper, the authors consider the problem of railway track degradation which is affected by the operational conditions, characteristics of bogie type, million gross tonnes (MGT), curvature, traffic type and environmental conditions. Wear and fatigue in rails are the major contributors of degradation of rails. Other factors such as grinding frequency, lubrication frequency and climatic conditions also affect the degradation. Estimation of parameters for developing failure models is required for the prediction of expected number of rail defects over a period of time in order to develope a preventive strategy.

    In the third paper, the failure mode and effect analysis (FMEA) is applied to analyze the railway signalling system performance, which is very critical for ensuring safety of railways and for safe running of trains by preventing occurrence of accidents and minimizing the risk to the passengers, operating personnel, and railway infrastructure. A measure, such as Risk Priority Number (RPN) is defined, which is a product of occurrence, severity, and detection. The study concludes that point and point machine, signal, and track circuit are the critical subsystems of a railway signalling system.

    In the fourth paper, the author highlights the importance of teamwork in any organization. Human performance is critical to overall performance of a system. A Team can be understood as a basic unit of an organization is expected to deliver improved performance as well as improved quality in working. The paper shows the importance of balancing the implementation and development of teamwork in organizations (that is, a "soft" issue) with the improvement of "hard" system performance. Based on a study involving more than 160 teams at Volvo Trucks in Sweden, the concept of performability is introduced to understand work teams. This concept has been applied in various organizations in Europe and can be extended to the operation of critical transportation system such as railways.

    In the fourth paper, the design features and performance of an Automatic Control System (ATC) is examined. ATC is basically a system which supervises the engine and the driver. At signals, data such as permitted speed, distance to next signal, gradient and speed required etc are transmitted to engine. The data is displayed to the driver and if driver is not performing correctly ATC will take over and brake the train. The increasing level of train traffic and the spread of high-speed rail lines are demanding an increasing safety level in the ATC systems. ATC systems are based both on trackside and onboard systems and their evolution has followed the introduction of new technologies. The European Vital Computer (EVC) is the core of the onboard ATC system; it supervises the movement of the train by using the information received from the trackside systems.

    In the fifth paper, the authors highlight the importance of a reliable rolling stock and infrastructure equipment in railways. This eventually plays an important role in achieving high levels of safety. Therefore, the railway industry uses strategy of improving the performance of different subsystems in order to ensure safety and reliability. In fact reliability analysis is necessary in identifying bottlenecks in the system and to identify components or subsystems of low reliability for improving their performance. This paper actually provides a case study of a passenger train company of Iran and carries out reliability analysis which is used to determine the appropriate preventive maintenance strategy.

    In the sixth paper, the problem associated with the maintenance of railway track is considered. In fact, railway operations today place greater demands on the track than ever before due to emphasis on faster trains with heavier payloads. With this development, time to maintain track is becoming less and less and the quality of service has to meet increased customer expectations. This necessitates improving our understanding of track degradation mechanism. Overall tamping and renewing of ballast and track are traditionally part of maintenance scheduled on regular intervals and sometimes maintenance is performed when results on track measurement exceeds limits set. However, with focus on reducing cost, maintenance needs to be optimized. This paper presents a study which describes a model that has been developed to show the relations between the degradation and variables affecting this degradation, which can help in optimized maintenance strategy.

    In the last paper of this issue, with the railway tracks becoming electrified, the problem of electromagnetic interference is presented and its importance is highlighted to prevent faults that this interference can lead to in operation, with reference to Swiss railways.

    My special thanks are also due to several referees, who unhesitatingly helped us in reviewing and revising the submitted papers at short notice in order to materialize this issue and in bringing these papers to the present form.

    Original articles
    Use of Availability Concepts in the Railway System
    BIRRE NYSTRÖM
    2009, 5(2): 103-118.  doi:10.23940/ijpe.09.2.p103.mag
    Abstract    PDF (164KB)   
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    This paper explores and describes indicators related to availability in the railway system. Examples of indicators include train punctuality and condition of track. The paper presents losses to the stakeholders, measured by the indicators. Indicators in Banverket (Swedish Rail Administration) and railway literature are presented. Indicators used in the electric power industry are also presented, as these offer good analogies from which to develop additional railway indicators. The indicators found in the literature, but not in Banverket, include travel time variation, slack and wagons. Indicators found by analogy to the power industry concern passengers, traffic work not delivered and how to subtract the effects of adverse weather. A classification of availability indicators is also suggested.
    Received on June 21, 2008, revision available on December 03, 2008
    References: 36

    Parameter Estimation for Rail Degradation Model
    G. CHATTOPADHYAY, S. KUMAR
    2009, 5(2): 119-130.  doi:10.23940/ijpe.09.2.p119.mag
    Abstract    PDF (154KB)   
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    Wear and fatigue in rails are major contributors of rail degradation depending on operational conditions, track, characteristics of bogie type, Million Gross Tonnes (MGT), curvature, traffic type and environmental conditions. Estimation of parameter for failure models is necessary for accurate prediction of expected number of rail defects over a period of time based on MGT of traffic and operating conditions for developing cost effective maintenance strategies. This paper focuses on collection and analysis of field data over a period of time for estimation of parameter for modelling rail life.
    Received on December 12, 2007, revision available on December 02, 2008
    References: 13

    Failure Mode and Effect Analysis of Indian Railway Signalling System
    SUBHASH CHANDRA PANJA and PRADIP KUMAR RAY
    2009, 5(2): 131-141.  doi:10.23940/ijpe.09.2.p131.mag
    Abstract    PDF (128KB)   
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    Signalling, a complex system is one of the most important infrastructures of railway service. The performance of railway signalling system depends on the functioning of a number of subsystems, such as panel, cable, relay, point and point machine, track-circuit, signal, back indication, point-drive card, signal-drive card, and level crossing gate. Railway signalling system plays an important role for safe running of trains by preventing occurrence of accidents and minimizing the risk of the passengers, operating personnel, and railway infrastructure. Failure mode and effect analysis (FMEA) is applied to analyse the risk of these subsystems during the operating phase of railway signalling system. Risk is measured in terms of Risk Priority Number (RPN), which is a product of occurrence, severity, and detection. It is observed that point and point machine, signal, and track-circuit are the critical subsystems of railway signalling system.
    Received on December 24, 2007, revision available on October 14, 2008
    References: 11

    Performability of Work Teams: Balancing Hard and Soft Issues
    BEN S. KUIPERS
    2009, 5(2): 143-151.  doi:10.23940/ijpe.09.2.p143.mag
    Abstract    PDF (110KB)   
    Related Articles

    Teamwork plays a vital role in today's business environment, which is characterized by continual change and an increased demand for satisfaction by stakeholders. Teams can be understood as the basic units of an organization, as they are able to deliver improved business performance as well as improved quality of working life. This paper shows the importance of balancing the implementation and development of teamwork in organizations (that is, the "soft" issues) with the improvement of "hard" performance. Based on a longitudinal study involving more than 160 teams at Volvo Trucks in Sweden, the concept of performability is introduced to understand work teams, where this concept has, in fact, been applied at various organizations within the private sector as well as in the public sector throughout Europe.
    Received on March 28, 2008, revision available on July 27, 2008
    References: 24

    Design and Evaluation of a Safe Driver Machine Interface
    ANDREA BONDAVALLI, ANDREA CECCARELLI, JESPER GRØNBÆK, DANILO IOVINO, LUCIE KÁRNÁ, ŠTEPAN KLAPKA, TATIANA K. MADSEN, MELINDA MAGYAR, ISTVÁN MAJZIK, ANNA SALZO
    2009, 5(2): 153-166.  doi:10.23940/ijpe.09.2.p153.mag
    Abstract    PDF (346KB)   
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    Driver Machine Interface (DMI) is a slave unit of the train onboard computer in the ERTMS automatic train control system. The SAFEDMI project aimed at the development of a DMI which fulfills the requirements of Safety Integrity Level 2 according to the CENELEC development standards. The main challenges were (i) the reduction of the hardware complexity and costs by implementing the safety mechanisms in software and (ii) provide a safe and secure wireless communication interface to support diagnostics and maintenance. This paper presents the requirements, the design of the architecture and the wireless communication protocol, and the evaluation of the applied solutions.
    Received on June 10, 2008 and revision on September 18, 2008
    References: 25

    Reliability Analysis of the Rolling Stock Industry: A Case Study
    S.M. REZVANIZANIANI, J. BARABADY, M. VALIBEIGLOO, M. ASGHARI, and U. KUMAR
    2009, 5(2): 167-175.  doi:10.23940/ijpe.09.2.p167.mag
    Abstract    PDF (380KB)   
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    Provision of reliable rolling stock and infrastructure equipment is an important part in achieving high levels of safety. Therefore, the railway industry uses different methods and tools to improve the performance of different subsystems in order to ensure safety and reliability, which are the important factors for passengers and cargo transportation. Hence, reliability analysis is required to identify the bottlenecks in the system and find the components or subsystems with low reliability for a desired level of performance. This paper focuses on collection and analysis of field failure data over a period in Raja Passenger Train Company of Iran. The results of data analysis show that wheel sets is the bottleneck, and it utilizes the historical data of wheel sets to determine the reliability function. Thereafter, the reliability of each type of wheel sets are identified over different time intervals and which can be used to determine the appropriate time of preventive maintenance tasks.
    Received on September 7, 2008, revision available on December 21, 2008
    References: 6

    Railway Track Degradation: Shape and Influencing Factors
    NARVE LYNGBY
    2009, 5(2): 177-186.  doi:10.23940/ijpe.09.2.p177.mag
    Abstract    PDF (329KB)   
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    This paper presents the results of a study aiming at increase the knowledge of degradation phenomenon resulting in geometrical railway track irregularities. The paper show how data collected from ROGER 1000 together with variables affecting the degradation can be used to predict progression of railway track irregularities. The paper also describes a model which has been developed to show the relations between the irregularities and variables affecting it. The model has been developed using multivariable regression modeling.
    Received on December 19, 2007, revision available on December 02, 2008
    References: 08

    Electromagnetic Interference: A major Source of Faults in Swedish Railway
    STEFAN NISKA
    2009, 5(2): 187-196.  doi:10.23940/ijpe.09.2.p187.mag
    Abstract    PDF (325KB)   
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    Industry and the railway sector are at present entering a new era. Increasingly, the systems in operation today use electronic components instead of relay technique and the railway sector now has the opportunity to improve current systems. However when new technology is installed into old infrastructure, new knowledge has to be taken into consideration. The new technology which is to be integrated into old systems or which is to be applied when building systems from scratch should meet the requirements for electromagnetic compatibility to fit into the infrastructure. To see whether there are any problems in this area, an investigation has been performed based on the failure reporting system used by Banverket (Swedish Rail Administration). Visual inspection has been carried out in the signal and detector boxes located close to the track. Measurements on site have been conducted to follow up the investigation into the failure reporting system and the visual inspections.
    Received on February 25, 2008, revision available on September 29, 2008
    References: 16

    Short Communications
    Parametric Uncertainty Analysis of Complex System Reliability
    Peng Wang Tongdan Jin
    2009, 5(2): 197-199.  doi:10.23940/ijpe.09.2.p197.mag
    Abstract    PDF (71KB)   
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    This paper studies the uncertainties of component reliability parameters and their impact on system lifetime distribution. Monte Carlo simulation was applied to investigate the correlation between the system complexity and its Weibull shape parameter when component reliability parameters are estimated with uncertainties. Results show the system lifetime approaches the exponential distribution when the number of components becomes large.
    Received on August 1, 2008, revision available on October 21, 2008
    References: 06

ISSN 0973-1318