Introduction
1 Scope
2 References
2.1 Supporting standards
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 of integrity levels
5.4 Qualitative vs. quantitative methods
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 ranking
7.5 Existing hazard lists
8 Risk analysis
8.1 Risk tolerability
8.2 Determination of tolerable hazard rate
9 System design analysis
9.1 Appointment of safety integrity requirements
to functions
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 Proposed changes for annex A of ENV 50129
Annex E Frequently asked questions