IEC TR 62278-4:2016

IEC TR 62278-4 ®
Edition 1.0 2016-12
TECHNICAL
REPORT
Railway applications – Specification and demonstration of reliability, availability,
maintainability and safety (RAMS) –
Part 4: RAM risk and RAM life cycle aspects

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IEC TR 62278-4 ®
Edition 1.0 2016-12
TECHNICAL
REPORT
Railway applications – Specification and demonstration of reliability, availability,

maintainability and safety (RAMS) –

Part 4: RAM risk and RAM life cycle aspects

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 45.060.01 ISBN 978-2-8322-3672-7

– 2 – IEC TR 62278-4:2016 © IEC 2016

CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions. 6
3.2 Abbreviated terms . 7
4 Railway RAM . 7
4.1 General . 7
4.2 RAM risk . 7
4.2.1 RAM risk concept . 7
4.2.2 RAM risk analysis . 7
4.2.3 RAM risk evaluation and acceptance . 9
5 RAM life cycle . 11
5.1 General . 11
5.2 Requirements to be considered in phase 1. 11
5.3 System requirements for RAM in phase 4 . 11
5.3.1 Objectives . 11
5.3.2 Inputs . 11
5.3.3 Requirements . 11
5.3.4 Deliverables . 12
5.4 Requirements to be considered in phase 7. 12
Annex A (informative) Examples of reliability, availability and maintainability
parameters for railway applications . 13
Annex B (informative) Example of state transition diagram for IOCM . 15

Figure B.1 – Model of state transition diagram . 15

Table 1 – Example of categories of frequency of occurrence of PIOCM events . 8
Table 2 – Example of PIOCM severity levels . 8
Table 3 – Example of frequency – consequence matrix . 10
Table 4 – Example of qualitative RAM risk categories . 10
Table 5 – Example of RAM risk evaluation and acceptance. 10
Table A.1 – Examples of reliability parameters. 13
Table A.2 – Examples of availability parameters . 13
Table A.3 – Examples of transportation service parameters . 14
Table A.4 – Examples of comfort service parameters . 14
Table A.5 – Examples of maintenance parameters . 14

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS – SPECIFICATION AND DEMONSTRATION OF
RELIABILITY, AVAILABILITY, MAINTAINABILITY AND SAFETY (RAMS) –

Part 4: RAM risk and RAM life cycle aspects

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 62278-4, which is a technical report, has been prepared by IEC technical committee 9:
Electrical equipment and systems for railways.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
9/2184/DTR 9/2204A/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

– 4 – IEC TR 62278-4:2016 © IEC 2016
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62278 series, published under the general title Railway
applications – Specification and demonstration of reliability, availability, maintainabilty and
safety (RAMS), can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

INTRODUCTION
IEC 62278 series Railway applications – Specification and demonstration of reliability,
availability, maintainability and safety (RAMS) is issued for demonstration of the RAMS
aspects. It is based on the European Norm EN 50126:1999 that was prepared by Technical
Committee CENELEC TC 9X: Electrical and electronic applications for railways. It was
submitted to the National Committees for voting under the Fast Track Procedure. This
standard is widely used for safety requirements for the safety within the railway field, with
relevant safety standards for railway applications such as IEC 62425 and IEC 62279.
For rolling stock, the guidance on applying the RAM requirements in IEC 62278 is issued as
IEC TR 62278-3, which is aimed at the customers/operators and main suppliers of rolling
stock. The RAM aspects are important for the whole railway systems, not limited to rolling
stock. This means that the RAM aspects need to be elaborated upon in the current version of
IEC 62278.
IEC technical committee 9 set up Ad-hoc group 9 (AHG 9) with remit to study the possibilities
to develop a Technical Report giving input in order to allow the introduction of RAM risk and
RAM life cycle aspects in a future revision of EN 50126 by CENELEC TC 9X or of IEC 62278
by IEC TC 9. This technical report is the result of the study in AHG 9 in order to achieve
suitable RAM aspects in the future version of IEC 62278.

– 6 – IEC TR 62278-4:2016 © IEC 2016
RAILWAY APPLICATIONS – SPECIFICATION AND DEMONSTRATION OF
RELIABILITY, AVAILABILITY, MAINTAINABILITY AND SAFETY (RAMS) –

Part 4: RAM risk and RAM life cycle aspects

1 Scope
This part of IEC 62278 provides an idea for the expansion of the requirements relating only to
RAM aspects in IEC 62278.
This document is intended to be used as an input to the revision for the next edition of
IEC 62278. This technical report is entirely informative in nature and does not contain
normative aspects.
This document details the idea by means of referring to and revising the related clauses of the
current edition of IEC 62278.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 62278:2002, Railway applications – Specification and demonstration of reliability,
availability, maintainability and safety (RAMS)
3 Terms, definitions and abbreviated terms
For the purposes of this document, the terms and definitions given in IEC 62278 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Terms and definitions
3.1.1
impact on operation, comfort or maintenance
IOCM
combination of impact on operational capability, impact on passenger's comfort or impact on
maintenance
Note 1 to entry: examples of IOCM can be:
• for operational capability: delay, cancelation, stop on the line,
• for passenger comfort: degradation or loss of passenger information, air conditioning, lighting,
• for maintenance: failure without direct impact on operation or comfort, loss of diagnostic system.

3.1.2
potential impact on operation, comfort or maintenance
PIOCM
physical situation with a potential impact on operational capability, passenger's comfort or
maintenance
3.1.3
PIOCM Log
document in which all reliability, availability and
...