IEC IEC 62278-2 Edition 1.02025-07 INTERNATIONAL STANDARD Railway applications - Specification and demonstration of reliability, availability, maintainability and safety (RAMS) - Part 2: Systems approach to safety IEC 62278-2:2025-07(en) ICS 45.060.01 ISBN 978-2-8327-0584-1 THISPUBLICATIONIS COPYRIGHTPROTECTED Copyright@2025IEC,Geneva,Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local IEC member National Commitee for further information. IEC Secretariat Tel.: +41 22 919 02 11 3,rue de Varembe [email protected] CH-1211 Geneva 20 www.iec.ch Switzerland About the IEC The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies. About IEC publications The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the latest edition,a corrigendum oran amendment might have been published. IECpublicationssearch IEC Products & Services Portal -products.iec.ch webstore.iec.ch/advsearchform Discover our powerful search engine and read freely all the The advanced search enables to find IEC publications by a publications previews, graphical symbols and the glossary. variety of criteria (reference number, text, technical With a subscription you wili always have access to up to date committee, .).. It also gives. information on projects, content tailored to your needs. replaced and withdrawn publications Electropedia-www.electropedia.org IECJustPublished-webstore.iec.ch/justpublished The world's leading online dictionary on electrotechnology, Stay up to date on all new IEC publications. Just Published details all new publications released. Available online and and French, with equivalent terms in 25 additional languages. once a month by email Also known as the international Electrotechnical Vocabulary (IEV) online. IECCustomerServiceCentre-webstore.iec.ch/csc If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: [email protected]. Warning!Makesurethatyouobtainedthispublicationfromanauthorizeddistributor. IEC62278-2:2025@IEC2025 CONTENTS FOREWORD INTRODUCTION Scope 1 2 Normative references. 3 Terms and definitions.. 4 Abbreviatedterms. 5 Safety process .. .10 5.1 Hourglass model for risk assessment and hazard control. 10 5.2 A. Risk assessment. 5.2.1 General.. 11 5.2.2 Conducting risk assessment.. 12 5.3 B.Outcomeoftheriskassessment. 12 5.4 C. Hazard control........ 12 5.5 D. Revision of risk assessment. 13 5.6 Responsibilities.. 14 14 6 Safety demonstration and acceptance.. 6.1 General..... 14 6.2 Safety demonstration and safety acceptanceprocess. 14 6.3 Responsibility in managingthe safety case 6.4 Modifications after safety acceptance ... 18 6.5 Dependencies between safety cases ... 18 6.6 Relationship between safety cases and system architecture.. 19 Organization and independence of roles. 20 7.1 General.... .20 7.2 Early phases of the life cycle (phases 1to 4) 21 7.3 Laterphases of the life cycle (starting from phase 5) .21 7.4 Personnel competence 8 Risk assessment .24 8.1 General .24 8.2 Risk analysis 8.2.1 General... 8.2.2 The risk model ... .24 8.2.3 Techniques forthe consequence analysis .26 8.2.4 Expert judgement..... .27 8.3 Risk acceptance principles and risk evaluation... .28 8.3.1 Use ofcodeof practice 28 8.3.2 Use of a reference system.... ..28 8.3.3 Use of explicit risk estimation. 29 8.4 Application of explicit risk estimation . 30 8.4.1 Quantitative approach. 30 8.4.2 .33 Variability using quantitative risk estimates 8.4.3 Qualitative and semi-quantitative appro