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PD CLC/TR 50451:2007

Superseded
Superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

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superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

Railway applications. Systematic allocation of safety integrity requirements
Available format(s)

Hardcopy , PDF

Superseded date

11-30-2018

Language(s)

English

Published date

12-31-2010

Executive summary
Introduction
1 Scope
2 References
  2.1 Normative references
  2.2 Informative references
3 Definitions
4 Symbols and abbreviations
5 Safety Integrity Levels allocation framework
  5.1 Prerequisites
  5.2 Overview of the methodology
  5.3 Definition of Safety Integrity Levels
  5.4 Qualitative vs quantitative methods
      5.4.1 Qualitative assessment
      5.4.2 Quantitative assessment
  5.5 EN 50126-1 lifecycle context
6 System definition
7 Hazard identification
  7.1 General principles
  7.2 Empirical hazard identification methods
  7.3 Creative hazard identification methods
  7.4 Hazard
  7.5 Existing hazard lists
8 Risk analysis
  8.1 Risk tolerability
  8.2 Determination of Tolerable Hazard Rate
      8.2.1 Qualitative risk analysis
      8.2.2 Quantitative risk analysis
      8.2.3 GAMAB and similar approaches
      8.2.4 The MEM approach
      8.2.5 Other approaches
9 System design analysis
  9.1 Apportionment of safety integrity requirements
      to functions
      9.1.1 Physical independence
      9.1.2 Functional independence
      9.1.3 Process independence
  9.2 Use of SIL tables
  9.3 Identification and treatment of new hazards
      arising from design
  9.4 Determination of function and subsystem SIL
  9.5 Determination of safety integrity requirements
      for system elements
Annex A - Single-line signalling system example
Annex B - Level crossing example
Annex C - Comparison of demand and continuous mode
Annex D - Frequently asked questions

Describes a method to determine the required Safety Integrity Level of railway signalling equipment taking in consideration the operational conditions of the railway, and the architecture of the signalling system.

The scope of this Technical Report is to define a method to determine the required Safety Integrity Level of railway signalling equipment taking in consideration

  • the operational conditions of the railway, and

  • the architecture of the signalling system.

The following picture may be used in order to detail more precisely the scope of this Technical Report:

From a mechanistic point of view the task of this Technical Report is to define a method of calculation, which determines the integrity requirements (qualitatively and quantitatively) from the inputs stated above.

Committee
GEL/9/1
DevelopmentNote
Supersedes BS PD R009-004. (06/2007)
DocumentType
Standard
Pages
90
PublisherName
British Standards Institution
Status
Superseded
SupersededBy
Supersedes

Standards Relationship
CLC/TR 50451:2007 Identical

ISO/IEC 15026:1998 Information technology System and software integrity levels
R009-001 : 1997 RAILWAY APPLICATIONS COMMUNICATION, SIGNALLING AND PROCESSING SYSTEMS HAZARDOUS FAILURE RATES AND SAFETY INTEGRITY LEVELS (SIL)
EN 50128:2011/AC:2014 RAILWAY APPLICATIONS - COMMUNICATION, SIGNALLING AND PROCESSING SYSTEMS - SOFTWARE FOR RAILWAY CONTROL AND PROTECTION SYSTEMS
EN 50129 : 2003 COR 2010 RAILWAY APPLICATIONS - COMMUNICATION, SIGNALLING AND PROCESSING SYSTEMS - SAFETY RELATED ELECTRONIC SYSTEMS FOR SIGNALLING
EN 50126-1:2017 Railway Applications - The Specification and Demonstration of Reliability, Availability, Maintainability and Safety (RAMS) - Part 1: Generic RAMS Process
EN 50121-5:2017 Railway applications - Electromagnetic compatibility - Part 5: Emission and immunity of fixed power supply installations and apparatus
DEFSTAN 00-56/1(1991) : 1991 HAZARD ANALYSIS AND SAFETY CLASSIFICATION OF THE COMPUTER AND PROGRAMMABLE ELECTRONIC SYSTEM ELEMENTS OF DEFENCE EQUIPMENT

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