EN 50126 : 1999

Introduction
1 Scope
2 Normative References
3 Definitions
4 Railway RAMS
      4.1 Introduction
      4.2 Railway RAMS and quality of service
      4.3 Elements of railway RAMS
      4.4 Factors influencing railway RAMS
             4.4.1 General
             4.4.2 Categories of factors
             4.4.3 Management of factors
      4.5 The means to achieve railway RAMS requirements
             4.5.1 General
             4.5.2 RAMS specification
      4.6 Risk
             4.6.1 Risk concept
             4.6.2 Risk analysis
             4.6.3 Risk evaluation and acceptance
      4.7 Safety integrity
      4.8 Fail-safe concept
5 Management of railway RAMS
      5.1 General
      5.2 System lifecyclethe lifecycle
      5.3 Application of this standard
6 RAMS lifecycle
      6.1 Phase 1: Concept
      6.2 Phase 2: System definition and application
                       conditions
      6.3 Phase 3: Risk analysis
      6.4 Phase 4: System requirements
      6.5 Phase 5: Apportionment of system requirements
      6.6 Phase 6: Design and implementation
      6.7 Phase 7: Manufacturing
      6.8 Phase 8: Installation
      6.9 Phase 9: System validation (including safety
                       acceptance and commissioning)
      6.10 Phase 10: System acceptance
      6.11 Phase 11: Operation and maintenance
      6.12 Phase 12: Performance monitoring
      6.13 Phase 13: Modification and retrofit
      6.14 Phase 14: Decommissioning and disposal
Annex A (informative) Outline of RAMS specification - example
Annex B (informative) RAMS programme
Annex C (informative) Examples of parameters for railway
Annex D (informative) Examples of some risk acceptance
                      principles
Annex E (informative) Responsibilities within the RAMS process
                      throughout the lifecycle
Figure 1 - Quality of Service and Railways RAMS
Figure 2 - Inter-relation of Railway RAMS elements
Figure 3 - Effects of Failures Within a System
Figure 4 - Influences on RAMS
Figure 5 - Factors influencing Railway RAMS
Figure 6 - Example of a Cause/Effect Diagram
Figure 7 - Certified Products in Safety Systems
Figure 8 - System Lifecycle
Figure 9 - Project Phase Related Tasks (Sheet 2 of 2)
Figure 10 - The "V" Representation
Figure 11 - Verification and Validation
Figure 12 - RAMS Engineering and Management Implemented within
            a System Realization Process
Table 1 - RAM Failure Categories
Table 2 - Frequency of Occurrence of Hazardous Events
Table 3 - Hazard Severity Level
Table 4 - Frequency - Consequence Matrix
Table 5 - Qualitative Risk Categories
Table 6 - Typical Example of Risk Evaluation and Acceptance
Table B.1 - Example of a Basic RAMS Programme Outline
Table C.1 - Examples of Reliability Parameters
Table C.2 - Examples of Maintainability Parameters
Table C.3 - Examples of Availability Parameters
Table C.4 - Examples of Logistic Support Parameters
Table C.5 - Examples of Safety Performance Parameters

Defines RAMS as in terms of Reliability, Availability, Maintainability and Safety, and their interactions. Applicable to demonstrate and specify the RAMS for all railway applications at all levels; as an application, as appropriate, from complete railway routes to major systems within a route, to combined and individual components and sub-systems, including those containing software. Guidance on the applicability is within the requirements of this standard.