IEC 62425-2025 PDF

Full title and description

IEC 62425:2025 — Railway applications — Communication, signalling and processing systems — Safety related electronic systems for signalling. Edition 2.0 (2025) is a technical revision that replaces the first edition (2007) and updates life‑cycle alignment, safety‑case requirements and treatment of pre‑existing items for safety‑related railway signalling electronics.

Abstract

IEC 62425:2025 defines functional‑safety requirements for safety‑related electronic systems, subsystems and equipment used in railway signalling. The document covers specification, development, verification, validation, acceptance, operation, maintenance, modification and decommissioning phases with particular emphasis on life‑cycle phases 5–10 (architecture through system acceptance). It addresses reuse of pre‑existing items, safety cases, safety‑related tools and the limited treatment of cybersecurity where it affects functional safety.

General information

• Status: Published / Active (Edition 2.0, replaces 2007 edition)
• Publication date: 5 May 2025
• Publisher: International Electrotechnical Commission (IEC)
• ICS / categories: 45.060.01 — Railway rolling stock in general; Category: Safety
• Edition / version: Edition 2.0 (2025)
• Number of pages: 141.

Scope

This standard is applicable to safety‑related electronic systems (including subsystems and equipment) for railway signalling, for both generic products and systems designed for specific applications. It is limited to functional safety aspects (not occupational health and safety) and focuses on life‑cycle phases from architecture and requirement apportionment through system acceptance; it is not intended to retroactively require acceptance of systems already accepted prior to this edition, although modifications and extensions are covered where reasonably practicable.

Key topics and requirements

• Life‑cycle requirements for development, verification, validation, acceptance, operation, maintenance and modification (focus on phases 5–10).
• Defined structure and content requirements for the safety case (new dedicated clause).
• Guidance and requirements for reuse of pre‑existing systems and allocation of safety integrity requirements (updated Annex A).
• Requirements addressing safety‑related tools and treatment of cybersecurity risks insofar as they affect functional safety.
• Updated normative/informative status of annexes (merging and status changes) and addition of an informative annex on user‑programmable integrated circuits.
• Requirements for safety acceptance and approval processes and related documentation.

Typical use and users

Used by railway duty holders, signalling system and equipment suppliers, assessors, validation and verification teams, and safety authorities. Practitioners apply the standard when specifying, designing, verifying, accepting, maintaining or modifying safety‑related signalling equipment and subsystems, and when preparing safety cases and evidence for approval.

Related standards

Closely linked to life‑cycle and hazard analysis standards such as IEC 62278 (railway applications — rolling stock and life‑cycle phases) and other IEC/CENELEC railway and functional‑safety standards; practitioners should consider IEC 62425 in the context of the IEC 624xx family and applicable national railway regulations and guidance.

Keywords

railway, signalling, safety‑related electronic systems, functional safety, safety case, life cycle, IEC 62278, SIL allocation, pre‑existing items, safety acceptance

FAQ

Q: What is this standard?

A: An international standard (IEC 62425:2025, Edition 2.0) that sets functional‑safety requirements for electronic systems used in railway signalling and replaces the 2007 edition.

Q: What does it cover?

A: It covers functional‑safety requirements across the development and operational life cycle (with emphasis on architecture, requirement allocation and system acceptance), the structure and content of safety cases, reuse of pre‑existing items, safety‑related tools, and the limited treatment of cybersecurity issues that impact safety.

Q: Who typically uses it?

A: Railway operators and duty holders, signalling equipment and system suppliers, assessors and certification/approval bodies, system integrators and safety engineers involved in the design, verification and acceptance of signalling equipment and subsystems.

Q: Is it current or superseded?

A: Current — IEC 62425:2025 (Edition 2.0) is the active edition published 5 May 2025 and cancels and replaces IEC 62425:2007 (the 2007 edition was withdrawn on the date of the new publication).

Q: Is it part of a series?

A: It is part of IEC TC 9’s railway standards portfolio and is intended to be used alongside related IEC and CENELEC railway and functional‑safety standards (for example IEC 62278 and other IEC 624xx documents addressing signalling, safety and related topics).

Q: What are the key keywords?

A: Railway signalling, functional safety, safety case, life‑cycle, SIL allocation, safety acceptance, reuse of pre‑existing items, safety‑related tools, cybersecurity (safety impact).