International Standards and Conformity Assessment for all electrical, electronic and related technologies



Reference CLC/TR 50126-2:2007
Title Railway applications - The specification and demonstration of Reliability, Availability, Maintainability and Safety (RAMS) - Part 2: Guide to the application of EN 50126-1 for safety
Project Number 15359
Abstract/Scope 1.1 This Technical Report provides guidance on specific issues, listed under 1.3 below, for applying the safety process requirements in EN 50126 1 to a railway system and for dealing with the safety activities during the different system life cycle phases. The guidance is applicable to all systems covered within the scope of EN 50126-1. It assumes that the users of the report are familiar with safety matters but need guidance on the application of EN 50126-1 for safety issues that are not or could not be addressed in the standard in detail. 1.2 EN 50126-1 is the top-level basic RAMS standard. This application guide, CLC/TR 50126 2 forms an informative part of EN 50126-1 dealing explicitly with safety aspects as limited by the scope defined in 1.3 below. 1.3 Limitation of scope The scope is limited to providing guidance only for the following issues related to EN 50126 1. i) Production of a top-level generic risk model for the railway system down to its major constituents (e.g., signalling, rolling stock, infrastructure, etc.) with definition of the constituents of the model and their interactions. ii) Development of a checklist of common functional hazards within a conventional railway system (including high speed lines, Light Rail Train’s, metro’s, etc.). iii) Guidance on the application of the risk acceptance principles in EN 50126-1. iv) Guidance on the application of functional safety in railway systems and qualitative assessment of tolerable risk with examples. v) Guidance for specifying relevant functional safety requirements and apportionment of safety targets to the requirements for sub-systems (e.g. for rolling stock: door systems, brake systems, etc.). vi) Guidance on the application of safety integrity level concept, through all the life cycle phases of the system. vii) Guidance on methods for combining probabilistic and deterministic means for safety demonstration. viii) Guidance on the essentials (incl. maintenance, operation, etc.) for documented evidence or proof of safety (safety case) with proposals for a common structure for such documentation.


Current Stage code 6060
Current Stage code date 2007-02-22
Current Stage code deadline  
Deadline date for vote 2007-07-31


Order Voucher  


IEC Technical Body IEC/TC 9
Reference Document  
ICS 45.020 - Railway engineering in general
Keywords Railway; Reliability; Availability; Maintainability; RAMS
Special National Condition(s)  


Categories - Aspects
Product Life Cycle
All Risks to the environment from accidents or misuse Use B2B, B2C


Deadline Date
6060 2007-02-22   export to doc file  EN
5099 2007-01-22 2007-05-22  
5060 2007-01-08 2007-01-22 export to doc file  EN
5020 2006-09-29 2007-01-05 export to doc file  EN
3090 2006-06-14 2006-10-07  
3020 2005-07-28 2005-12-01  
2020 2003-12-03 2004-06-03  
1000 2002-07-02 2003-01-02  

Implementation Dates

date of Ratification (DOR) (1) 2007-01-22
date of Availability (DAV) (2) 2007-02-22
date of Announcement (DOA) (3) -
date of Publication (DOP) (4) -
date of Withdrawal (DOW) (5) -


Superseded by  
Normative reference (6) ISO/IEC Guide 51:1999
EN 50126-1:1999
CLC/TR 50126-3:2006
EN 50128:2001
EN 50129:2003
CLC/TR 50506-1:2007
IEC 60050-191:1990
EN 60300-3-1:2004
IEC 60300-3-9:1995
HD 485 S1:1987
HD 617 S1:1992
EN 61078:1993
EN 61160:2005
IEC 61165:1995
EN 61508-1:2001
EN 61703:2002
IEC 61882:2001

(1) Date of ratification (dor) date when the Technical Board notes the approval of an EN (and HD for CENELEC), from which time the standard may be said to be approved

(2) Date of availability (dav) date when the definitive text in the official language versions of an approved CEN/CENELEC publication is distributed by the Central Secretariat

(3) Date of announcement (doa) latest date by which the existence of an EN (and HD for CENELEC), a TS or a CWA has to be announced at national level

(4) Date of publication (dop) latest date by which an EN has to be implemented at national level by publication of an identical national standard or by endorsement

(5) Date of withdrawal (dow) latest date by which national standards conflicting with an EN (and HD for CENELEC) have to be withdrawn

(6) This list of normative references is purely indicative. The only official list of normative reference is the list of the published standard.