SIST EN 50126-2:2018/A1:2025

Railway Applications - The Specification and Demonstration of Reliability, Availability, Maintainability and Safety (RAMS) - Part 2: Systems Approach to Safety

Scope remains the same as EN50126-2:2017

Bahnanwendungen - Spezifikation und Nachweis von Zuverlässigkeit, Verfügbarkeit, Instandhaltbarkeit und Sicherheit (RAMS) - Teil 2: Systembezogene Sicherheitsmethodik

Applications ferroviaires - Spécification et démonstration de la fiabilité, de la disponibilité, de la maintenabilité et de la sécurité (FDMS) - Partie 2: Approche systématique pour la sécurité

Železniške naprave - Specifikacija in prikaz zanesljivosti, razpoložljivosti, vzdrževalnosti in varnosti (RAMS) - 2. del: Sistemski pristop k varnosti - Dopolnilo A1

General Information

• Status: Published
• Public Enquiry End Date: 30-Apr-2023
• Publication Date: 09-Dec-2024
• ICS: 03.120.01 - Quality in general
• ICS: 45.020 - Railway engineering in general
• Technical Committee: ŽEN - Electrical applications for railways
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 20-Nov-2024
• Due Date: 25-Jan-2025
• Completion Date: 10-Dec-2024
• Directive: 2016/797/EU - Directive (EU) 2016/797 of the European Parliament and of the Council of 11 May 2016 on the interoperability of the rail system within the European Union (Text with EEA relevance)
• Mandate: M/483 - Mandate for programming and standardisation addressed to the European standardisation bodies under directive 2008/57/EC in the field of the interoperability of the rail system within the European Union
• Mandate: M/591 - Standardisation request to the European Committee for Standardisation and the European Committee for Electrotechnical Standardisation as regards railway products in support of Directive (EU) 2016/797
• Ref Project: EN 50126-2:2017/A1:2024 - Railway applications - The specification and demonstration of Reliability, Availability, Maintainability and Safety (RAMS) - Part 2: Systems approach to safety

Relations

• Amends: SIST EN 50126-2:2018 - Railway Applications - The Specification and Demonstration of Reliability, Availability, Maintainability and Safety (RAMS) - Part 2: Systems Approach to Safety
• Effective Date: 01-Jan-2025

Overview

SIST EN 50126-2:2018/A1:2025 is a pivotal European standard developed by CLC that addresses railway applications focusing on the specification and demonstration of Reliability, Availability, Maintainability, and Safety (RAMS). Specifically, Part 2 of this series presents a comprehensive systems approach to safety. This amendment A1, published in 2024, updates the original 2017 edition with crucial clarifications and enhancements while maintaining the original scope. The standard forms part of the EN 50126 series, which collectively provides a framework to ensure safety integrity and risk management in railway systems.

This document supports railway industry stakeholders involved in the design, deployment, and operation of rail systems to align with essential safety directives and interoperability requirements under the European Union regulatory framework.

Key Topics

• Systems Approach to Safety: SIST EN 50126-2:2018/A1:2025 emphasizes a holistic view of safety that integrates system-level risk assessments, safety demonstration, and acceptance criteria.

• Safety Demonstration and Acceptance: The standard outlines processes for demonstrating that the safety requirements are met, ensuring compliance with the RAMS framework.

• Risk Assessment Methodologies: Updated clauses refine procedures for identifying, analyzing, and mitigating risks within rail systems to meet functional safety standards.

• Safety Integrity Requirements: The amendment revises apportionment rules for functional safety integrity requirements, including classification of safety functions with attributes such as “basic integrity.”

• Roles and Responsibilities: Annex G clarifies the qualifications and responsibilities of key roles involved in managing system safety, aligning with the EN 50126 series requirements.

• EU Interoperability Alignment: Annex ZZ provides detailed mappings between EN 50126-2 and EU Directives-particularly Directive (EU) 2016/797-ensuring conformity with essential safety and interoperability requirements for control-command, signalling, rolling stock, and freight wagons.

• Harmonization with EN 50126 Series: Terminology and normative references have been updated to reflect consistent use across the EN 50126 family, reinforcing a unified framework for RAMS processes.

Applications

SIST EN 50126-2:2018/A1:2025 is applicable to railway organizations and system integrators implementing and maintaining safety-critical systems in the rail industry. Key practical applications include:

• Railway System Design: Supporting system engineers in developing and verifying safety requirements for rail infrastructure, rolling stock, and control-command systems.

• Safety Management: Assisting safety managers and validators in establishing safety cases and conducting conformity assessments in compliance with EU directives and interoperability specifications.

• Risk Mitigation Strategies: Guiding risk analysts and assessors in applying the most effective safety assurance methods, including hazard identification and functional safety integrity allocation.

• Maintenance Planning: Informing maintenance planners about safety-relevant processes to sustain system reliability and availability across the asset lifecycle.

• Regulatory Compliance: Facilitating alignment with European legislative frameworks, easing licensing, certification, and market access within the EU and EFTA member states.

• Training and Competency Development: Enhancing the understanding of safety-related roles through defined competency requirements tailored to the railway sector.

Related Standards

• EN 50126-1:2017: The generic RAMS process standard, referenced normatively for defining terms and foundational processes within the EN 50126 series.

• EU Directive (EU) 2016/797: The principal legislative document governing railway system interoperability in the European Union, with which EN 50126-2 provides presumption of conformity.

• Technical Specifications for Interoperability (TSI): Various TSIs for rolling stock, control-command, signalling, and freight wagons that reference EN 50126-2 clauses for safety requirements compliance.

• EN ISO 9001: Quality management standard integrated by cross-reference regarding organizational and competency requirements for RAMS functions.

• Other EN 50126 Series Parts: Additional parts addressing RAMS processes, validation, and lifecycle aspects that complement Part 2’s systems safety approach.

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Keywords: SIST EN 50126-2:2018/A1:2025, Railway applications, RAMS, systems approach to safety, railway safety standards, risk assessment, functional safety, EU interoperability, railway system safety, CLC railway standards, railway reliability, maintainability, availability, EU Directive 2016/797, European railway safety compliance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2025
Železniške naprave - Specifikacija in prikaz zanesljivosti, razpoložljivosti,
vzdrževalnosti in varnosti (RAMS) - 2. del: Sistemski pristop k varnosti - Dopolnilo
A1
Railway Applications - The Specification and Demonstration of Reliability, Availability,
Maintainability and Safety (RAMS) - Part 2: Systems Approach to Safety
Bahnanwendungen - Spezifikation und Nachweis von Zuverlässigkeit, Verfügbarkeit,
Instandhaltbarkeit und Sicherheit (RAMS) - Teil 2: Systembezogene Sicherheitsmethodik
Applications ferroviaires - Spécification et démonstration de la fiabilité, de la disponibilité,
de la maintenabilité et de la sécurité (FDMS) - Partie 2: Approche systématique pour la
sécurité
Ta slovenski standard je istoveten z: EN 50126-2:2017/A1:2024
ICS:
03.120.01 Kakovost na splošno Quality in general
45.020 Železniška tehnika na Railway engineering in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50126-2:2017/A1

NORME EUROPÉENNE
EUROPÄISCHE NORM November 2024
ICS 45.020
English Version
Railway applications - The specification and demonstration of
Reliability, Availability, Maintainability and Safety (RAMS) -
Part 2: Systems approach to safety
Applications ferroviaires - Spécification et démonstration de Bahnanwendungen - Spezifikation und Nachweis von
la fiabilité, de la disponibilité, de la maintenabilité et de la Zuverlässigkeit, Verfügbarkeit, Instandhaltbarkeit und
sécurité (FDMS) - Partie 2: Approche systématique pour la Sicherheit (RAMS) - Teil 2: Systembezogene
sécurité Sicherheitsmethodik
This amendment A1 modifies the European Standard EN 50126-2:2017; it was approved by CENELEC on 2024-10-14. CENELEC
members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this amendment the
status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This amendment exists in three official versions (English, French, German). A version in any other language made by translation under the
responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as
the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50126-2:2017/A1:2024 E

Contents Page
European foreword . 3
1 Modification to the European foreword . 4
2 Modifications to the Introduction . 4
3 Modification to Clause 1, “Scope” . 4
4 Modification to Clause 2, “Normative references” . 4
5 Modification to Clause 3, “Terms and definitions” . 4
6 Modification to Clause 6, “Safety demonstration and acceptance” . 4
7 Modification to Clause 8, “Risk assessment” . 4
8 Modification to Clause 10, “Apportionment of functional Safety Integrity requirements” . 4
9 Modification to Annex G, “Key system safety roles and responsibilities” . 4
10 Modification to Annex ZZ, “Relationship between this European Standard and the Essential
Requirements of EU Directive 2008/57/EC” . 5
11 Modification to the Bibliography . 8
European foreword
This document (EN 50126-2:2017/A1:2024) has been prepared by Technical Committee CLC/TC 9X “Electrical
and electronic applications for railways”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2025-11-30
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2027-11-30
conflicting with this document have to be
withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CENELEC by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZZ, which is an integral part of this document.
Any feedback and questions on this document should be directed to the users’ national committee. A complete
listing of these bodies can be found on the CENELEC website.
1 Modification to the European foreword
In the fourth paragraph, replace “the new editions EN 50126-1:2017 and EN 50126-2:2017” with “the new
editions of the EN 50126 series”.
2 Modifications to the Introduction
In the second paragraph, replace “EN 50126” with “the EN 50126 series”.
In the fifth paragraph, replace “EN 50126 forms part of” with “the EN 50126 series forms part of”.
In the seventh paragraph, replace “EN 50126-1 and EN 50126-2 are” with “the EN 50126 series is”.
3 Modification to Clause 1, “Scope”
In the first paragraph, replace “This part 2 of EN 50126” with “this document”.
In the first paragraph, fist list item of the third bullet point, replace “a key concept of EN 50126” with “a key
concept of the EN 50126 series”.
Replace the following text:
In the second paragraph, replace “This part 2 of EN 50126” with “this document”.
4 Modification to Clause 2, “Normative references”
Replace the normative reference with the following:
EN 50126-1:2017, Railway applications - The specification and demonstration of Reliability, Availability,
Maintainability and Safety (RAMS) - Part 1: Generic RAMS process
5 Modification to Clause 3, “Terms and definitions”
Replace “EN 50126-1” with “EN 50126-1:2017”.
6 Modification to Clause 6, “Safety demonstration and acceptance”
In 6.2, last paragraph, replace “EN 50126-1” with “EN 50126-1:2017”.
7 Modification to Clause 8, “Risk assessment”
In 8.2.3, last paragraph, replace “EN 50126-1” with “EN 50126-1:2017”.
8 Modification to Clause 10, “Apportionment of functional Safety Integrity
requirements”
In 10.2.7, replace the penultimate paragraph with the following:
−5 -1
“In case the derived TFFR is equal to 10 h or higher (less demanding), the function shall be given the attribute
of “basic integrity”, with related requirements defined in 10.2.11.”
9 Modification to Annex G, “Key system safety roles and responsibilities”
In Table G.1, replace “13. understand the relevant parts of EN 50126” with “13. understand the relevant parts
of the EN 50126 series”.
As impacted by EN 50126-1:2017/A1:2024.
In Table G.2, replace “8. understand the relevant parts of EN 50126” with “8. understand the relevant parts of
the EN 50126 series”.
In Table G.3, replace “6. understand the requirements of EN 50126” with “6. understand the requirements of
the EN 50126 series”.
In Table G.4, replace “5. be competent in understanding the relevant safety, human resource, technical and
quality management processes in fulfilling the requirements of the EN 50126” wi
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