EN 50126-1:2017

SLOVENSKI STANDARD
01-januar-2018
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Railway Applications - The Specification and Demonstration of Reliability, Availability,
Maintainability and Safety (RAMS) - Part 1: Generic RAMS Process
Bahnanwendungen - Spezifikation und Nachweis von Zuverlässigkeit, Verfügbarkeit,
Instandhaltbarkeit und Sicherheit (RAMS) - Teil 1: Generischer RAMS Prozess
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Ta slovenski standard je istoveten z: EN 50126-1:2017
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 50126-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2017
ICS 29.280; 45.020 Supersedes EN 50126-1:1999
English Version
Railway Applications - The Specification and Demonstration of
Reliability, Availability, Maintainability and Safety (RAMS) - Part
1: Generic RAMS Process
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 1: Processus FMDS générique Sicherheit (RAMS) - Teil 1: Generischer RAMS Prozess
This European Standard was approved by CENELEC on 2017-07-03. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard 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 European Standard 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50126-1:2017 E
Contents Page
European foreword . 6
Introduction . 7
1 Scope . 8
2 Normative references . 9
3 Terms and definitions . 9
4 Abbreviations . 20
5 Railway RAMS . 20
5.1 Introduction . 20
5.2 Multi-level System approach . 21
5.2.1 Concepts of system hierarchy . 21
5.2.2 System requirements and characteristics . 22
5.2.3 Defining a system . 23
5.3 Railway system overview . 23
5.3.1 Introduction . 23
5.3.2 Stakeholders involved in a railway system . 23
5.3.3 Railway system structure and apportionment of RAMS requirements . 24
5.4 Railway RAMS and quality of service . 24
5.5 Elements of railway RAMS . 24
5.6 Factors influencing railway RAMS . 27
5.6.1 General . 27
5.6.2 Classes of failures . 27
5.6.3 Derivation of detailed railway specific influencing factors . 27
5.6.4 Human factors . 32
5.7 Specification of railway RAMS requirements . 34
5.7.1 General . 34
5.7.2 RAMS specification . 34
5.8 Risk based approach . 34
5.9 Risk reduction strategy . 35
5.9.1 Introduction . 35
5.9.2 Reduction of risks related to safety . 35
5.9.3 Reduction of risks related to RAM . 36
6 Management of railway RAMS – general requirements . 37
6.1 Introduction . 37
6.2 Life cycle for the system under consideration. 37
6.3 Risk assessment . 45
6.4 Organisational requirements . 46
6.4.1 Introduction . 46
6.4.2 Requirements . 47
6.5 Application of this standard and adaptability to project scope and size . 47
6.5.1 General requirements . 47
6.5.2 Case of complex systems with different hierarchical levels. 49
6.5.3 Renewal within existing systems . 50
6.5.4 Re-use or adaptation of a system with previous acceptance. 50
6.6 General requirements on RAMS documentation . 51
6.7 Verification and Validation . 52
6.7.1 Introduction . 52
6.7.2 Verification. 52
6.7.3 Validation . 52
6.8 Independent Safety Assessment . 53
6.8.1 Objectives . 53
6.8.2 Activities . 54
7 RAMS life cycle . 55
7.1 General . 55
7.2 Phase 1: Concept . 55
7.2.1 Objectives . 55
7.2.2 Activities . 56
7.2.3 Deliverables . 56
7.3 Phase 2: System definition and operational context . 56
7.3.1 Objectives . 56
7.3.2 Activities . 56
7.3.3 Deliverables . 60
7.4 Phase 3: Risk analysis and evaluation . 60
7.4.1 Objectives . 60
7.4.2 Activities . 61
7.4.3 Deliverables . 64
7.5 Phase 4: Specification of system requirements . 64
7.5.1 Objectives . 64
7.5.2 Activities . 65
7.5.3 Deliverables . 66
7.5.4 Specific validation tasks . 66
7.6 Phase 5: Architecture and apportionment of system requirements . 67
7.6.1 Objectives . 67
7.6.2 Activities . 67
7.6.3 Deliverables . 68
7.7 Phase 6: Design and Implementation . 68
7.7.1 Objectives . 68
7.7.2 Activities . 68
7.7.3 Deliverables . 69
7.7.4 Specific verification tasks . 70
7.8 Phase 7: Manufacture . 70
7.8.1 Objectives . 70
7.8.2 Activities . 70
7.8.3 Deliverables . 71
7.9 Phase 8: Integration . 71
7.9.1 Objectives . 71
7.9.2 Activities . 71
7.9.3 Deliverables . 72
7.9.4 Specific verification tasks . 72
7.10 Phase 9: System Validation . 73
7.10.1 Objectives . 73
7.10.2 Activities . 73
7.10.3 Deliverables . 73
7.11 Phase 10: System acceptance . 74
7.11.1 Objectives . 74
7.11.2 Activities . 75
7.11.3 Deliverables . 75
7.12 Phase 11: Operation, maintenance and performance monitoring . 75
7.12.1 Objectives . 75
7.12.2 Activities . 75
7.12.3 Deliverables . 78
7.12.4 Specific verification tasks . 79
7.13 Phase 12: Decommissioning . 79
7.13.1 Objectives . 79
7.13.2 Activities . 79
7.13.3 Deliverables . 79
8 Safety Case . 79
8.1 Purpose of a safety case . 79
8.2 Content of a safety case . 80
Annex A (informative) RAMS plan . 82
A.1 General. 82
A.2 Procedure . 82
A.3 Basic RAMS plan example . 82
A.4 List of techniques . 84
Annex B (informative) Examples of parameters for railway . 86
B.1 General. 86
B.2 Reliability parameters . 86
B.3 Maintainability parameters . 86
B.4 Availability parameters . 87
B.5 Logistic support parameters . 89
B.6 Safety parameters . 89
Annex C (informative) Risk matrix calibration and risk acceptance categories . 90
C.1 General. 90
C.2 Frequency of occurrence categories . 90
C.3 Severity categories . 92
C.4 Risk acceptance categories . 93
Annex D (informative) Guidance on system definition . 95
D.1 General. 95
D.2 System Definition in an iterative system approach . 95
D.3 Method for defining the structure of a system . 95
D.3.1 General . 95
D.3.2 Function List . 95
D.3.3 Functional breakdown . 95
D.4 Parties/stakeholders/boundaries of systems . 96
D.5 Guidance on the content of a system definition . 96
Annex ZZ (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2008/57/EC . 98
Bibliography . 102

Table 1 — RAMS tasks along life-cycle phases (1 of 4) . 41
Table A.1 – Example of a basic RAMS plan outline (part 1 of 2) . 83
Table B.1 – Examples of reliability parameters . 86
Table B.2 – Examples of maintainability parameters . 86
Table B.3 – Examples of availability parameters . 87
Table B.4 – Examples of logistic support parameters . 90
Table B.5 – Examples of safety performance parameters . 90
Table C.1 – Frequency of occurrence of hazardous events with examples for quantification
(time based) . 91
Table C.2 – Frequency of occurrence of events with examples for quantification (distance based) . 92
Table C.3 – Severity categories (example related to RAM) . 93
Table C.4 – Severity categories (example 1 related to RAMS) . 93
Table C.5 – Severity categories (example 2 related to Safety) . 94
Table C.6 – Financial severity categories (example) . 94
Table C.7 – Risk acceptance categories (example 1 for binary decisions) . 94
Table C.8 – Risk acceptance categories (example 2) . 94
Table C.9 – Risk acceptance categories (example related to safety) . 95
Table D.1 – Typical examples for a functional breakdown . 97
European foreword
This document (EN 50126-1:2017) has been prepared by CLC/TC 9X "Electrical and electronic
applications for railways".
The following dates are fixed:
• latest date by which this document has (dop) 2018-07-03
to be implemented at national level by
publication of an identical national
standard or by endorsement
latest date by which the national (dow) 2020-07-03
•
standards conflicting with this document
have to be withdrawn
This document supersedes EN 50126-1:1999 which has been technically revised.
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.
EN 50126 "Railway applications – The specification and demonstration of Reliability, Availability,
Maintainability and Safety (RAMS)" consists of the following parts:
— Part 1: Generic RAMS process;
— Part 2: System approach to safety.
This document has been prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive(s).
For the relationship with EU Directive(s) see informative Annex ZZ, which is an integral part of this
document.
Introduction
EN 50126-1:1999 was aimed at introducing the application of a systematic RAMS management process
in the railway sector. Through the application of this standard and the experiences gained over the last
years, the need for revision and restructuring became apparent with a need to deliver a systematic and
coherent approach to RAMS applicable to all the railway application fields Command, Control and
Signalling (Signalling), Rolling Stock and Electric power supply for Railways (Fixed Installations).
The revision work improved the coherency and consistency of the standard, the concept of safety
management and the practical usage of EN 50126, and took into consideration the existing and related
Technical Reports as well.
This European Standard provides railway duty holders and the railway suppliers, throughout the
European Union, with a process which will enable the implementation of a consistent approach to the
management of reliability, availability, maintainability and safety, denoted by the acronym RAMS.
Processes for the specification and demonstration of RAMS requirements are cornerstones of this
standard. This European Standard promotes a common understanding and approach to the
management of RAMS.
EN 50126 forms part of the railway sector specific application of IEC 61508. Meeting the requirements in
this European Standard together with the requirements of other suitable standards is sufficient to ensure
that additional compliance to IEC 61508 does not need to be demonstrated.
With regard to safety, EN 50126-1 provides a Safety Management Process which is supported by
guidance and methods described in EN 50126-2.
EN 50126-1 and EN 50126-2 are independent from the technology used. As far as safety is concerned,
EN 50126 takes the perspective of safety with a functional approach.
The application of this standard can be adapted to the specific requirements for the system under
consideration.
This European Standard can be applied systematically by the railway duty holders and railway suppliers,
throughout all phases of the life cycle of a railway application, to develop railway specific RAMS
requirements and to achieve compliance with these requirements. The system-level approach
developed by this European Standard facilitates assessment of the RAMS interactions between
elements of railway applications even if they are of complex nature.
This European Standard promotes co-operation between the stakeholders of Railways in the
achievement of an optimal combination of RAMS and cost for railway applications. Adoption of this
European Standard will support the principles of the European Single Market and facilitate European
railway inter-operability.
1)
In accordance with CENELEC editing rules , mandatory requirements in this standard are indicated
with the modal verb “shall”. Where justifiable, the standard permits process tailoring.
Specific guidance on the application of this standard for Safety aspects is provided in EN 50126-2.
EN 50126-2 provides various methods for use in the safety management process. Where a particular
method is selected for the system under consideration, the mandatory requirements for this method are
by consequence mandatory for the safety management of the system under consideration.
This European Standard consists of the main part (Clause 1 to Clause 8) and Annexes A, B, C, D and
ZZ. The requirements defined in the main part of the standard are normative, whilst Annexes are
informative.
—————————
1) CEN/CENELEC Internal Regulations Part 3: Rules for the structure and drafting of CEN/CENELEC Publications
(2017-02), Annex H.
1 Scope
This part 1 of EN 50126
• considers RAMS, understood as reliability, availability, maintainability and safety and their
interaction;
• considers the generic aspects of the RAMS life cycle. The guidance in this part can still be used in
the application of specific standards;
• defines:
– a process, based on the system life cycle and tasks within it, for managing RAMS;
– a systematic process, tailorable to the type and size of the system under consideration, for
specifying requirements for RAMS and demonstrating that these requirements are achieved;
• addresses railway specifics;
• enables conflicts between RAMS elements to be controlled and managed effectively;
• does not define:
– RAMS targets, quantities, requirements or solutions for specific railway applications;
– rules or processes pertaining to the certification of railway products against the requirements of
this standard;
– an approval process for the railway stakeholders.
This part 1 of EN 50126 is applicable to railway application fields, namely Command, Control and
Signalling, Rolling Stock and Fixed Installations, and specifically:
• to the specification and demonstration of RAMS for all railway applications and at all levels of such
an application, as appropriate, from complete railway systems to major systems and to individual
and combined subsystems and components within these major systems, including those containing
software; in particular:
– to new systems;
– to new systems integrated into existing systems already accepted, but only to the extent and
insofar as the new system with the new functionality is being integrated. It is otherwise not
applicable to any unmodified aspects of the existing system;
– as far as reasonably practicable, to modifications and extensions of existing systems already
accepted, but only to the extent and insofar as existing systems are being modified. It is
otherwise not applicable to any unmodified aspect of the existing system;
• at all relevant phases of the life cycle of an application;
• for use by railway duty holders and the railway suppliers.
It is not required to apply this standard to existing systems which remain unmodified, including those
systems already compliant with any former version of EN 50126.
The process defined by this European Standard assumes that railway duty holders and railway suppliers
have business-level policies addressing Quality, Performance and Safety. The approach defined in this
standard is consistent with the application of quality management requirements contained within EN
ISO 9001.
2 Normative references
Not applicable.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acceptance
status achieved by a product, system or process once it has been agreed that it is suitable for its
intended purpose
3.2
accident
unintended event or series of events that results in death, injury, loss of a system or service, or
environmental damage
[SOURCE: IEC 60050-821: FDIS2016, 821-12-02]
3.3
approval
permission for a product or process to be marketed or used for stated purposes or under stated
conditions
Note 1 to entry: Approval can be based on fulfilment of specified requirements or completion of specified
procedures.
[SOURCE: EN ISO/IEC 17000:2004, 7.1]
[SOURCE: IEC 60050-902:2013, 902-06-01]
3.4
assurance
confidence in achieving a goal being pursued. Declaration intended to give confidence
3.5
audit
systematic, independent, documented process for obtaining records, statements of fact or other relevant
information and assessing them objectively to determine the extent to which specified requirements are
fulfilled
Note 1 to entry: Whilst “audit” applies to management systems, “assessment” applies to conformity assessment
bodies as well as more generally.
[SOURCE: EN ISO/IEC 17000:2004, 4.4, modified – The references to other terms within ISO/IEC
17000 have been replaced by hyperlinks to entries in the IEV.]
[SOURCE: IEC 60050-902:2013, 902-03-04]
3.6
availability,
ability of an item to be in a state to perform a required function under given conditions at a given instant
of time or over a given time interval, assuming that the required external resources are provided
[SOURCE: IEC 60050-821: FDIS2016, 821-05-82, modified]
3.7
basic integrity
-5 -1
integrity attribute for safety related function with a TFFR higher than (less demanding) 10 [h ] or non-
safety-related function.
3.8
collective risk
risk, resulting from e.g. a product, process or system, to which a population or group of people is
exposed
Note 1 to entry: Collective risk is not to be confused with risk of multiple victim accident.
Note 2 to entry: Collective risk is the sum of the individual risks to those individuals in the population or group.
However, the collective risk divided by the number of individuals will only provide the average individual risk.
Note 3 to entry: A group of people could be, for example, rail staff working in a restaurant car or all passengers
using a particular network.
3.9
commercial off-the-shelf product
product defined by market-driven need, commercially available and whose fitness for purpose has been
deemed acceptable by a broad spectrum of commercial users
[SOURCE: EN 50128:2011, 3.1.3, modified]
3.10
common cause failure
failures of multiple items, which would otherwise be considered independent of one another, resulting
from a single cause
[SOURCE: IEC 60050-192:2015, 192-03-18]
3.11
compliance
state where a characteristic or property of a product, system or process satisfies the specified
requirements
3.12
configuration management
process of identifying and documenting the characteristics of a facility’s structures, systems and
components (including computer systems and software), and of ensuring that changes to these
characteristics are properly developed, assessed, approved, issued, implemented, verified, recorded
and incorporated into the facility documentation
[SOURCE: IAEA 3, modified]
[SOURCE: IEC 60050-395:2014, 395-07-52]
3.13
consequence analysis
analysis of events which are likely to happen after a hazard has occurred
[SOURCE: IEC 60050-821: FDIS2016, 821-12-14]
3.14
corrective maintenance
maintenance carried out after fault detection to effect restoration
Note 1 to entry: Corrective maintenance of software invariably involves some modification.
[SOURCE: IEC 60050-192:2015, 192-06-06]
3.15
design
activity applied in order to analyse and transform specified requirements into acceptable solutions
[SOURCE: IEC 60050-821: FDIS2016, 821-12-16, modified]
3.16
deterministic
expresses that a behaviour can be predicted with certainty
Note 1 to entry: A deterministic event in a system can be predicted with certainty from preceding events which are
either known or are the same as for a proven equivalent system.
3.17
diversity
existence of two or more different ways or means of achieving a specified objective
Note 1 to entry: Diversity is specifically provided as a defence against common cause failure. It can be achieved by
providing systems that are physically different from each other or by functional diversity, where similar systems
achieve the specified objective in different ways.
[SOURCE: IEC 60050-395:2014, 395-07-115]
3.18
entity
person, group or organisation who fulfils a role as defined in this standard
3.19
equivalent fatality
expression of fatalities and weighted injuries and a convention for combining injuries and fatalities into
one figure for ease of evaluation and comparison of risks
3.20
error
discrepancy between a computed, observed or measured value or condition and the true, specified or
theoretically correct value or condition
Note 1 to entry: An error can be caused by a faulty item, e.g. a computing error made by faulty computer
equipment.
Note 2 to entry: A human error can be seen as a human action or inaction that can produce an unintended result.
[SOURCE: IEC 60050-192:2015, 192-03-02]
3.21
failure,
loss of ability to perform as required
Note 1 to entry: Qualifiers, such as catastrophic, critical, major, minor, marginal and insignificant, may be used to
categorize failures according to the severity of consequences, the choice and definitions of severity criteria
depending upon the field of application.
Note 2 to entry: Qualifiers, such as misuse, mishandling and weakness, may be used to categorize failures
according to the cause of failure.
[SOURCE: IEC 60050-192:2015, 192-03-01, modified Note 1 to entry has been omitted]
[SOURCE: IEC 60050-821:FDIS2016, 821-11-19]
Note 3 to entry: "Failure" is an event, as distinguished from "fault", which is a state.
3.22
failure mode
manner in which failure occurs
[SOURCE: IEC 60050-192:2015, 192-03-17]
3.23
failure rate
limit of the ratio of the conditional probability that the instant of time, T, of a failure of a product falls
within a given time interval (t, t + Δt) and the duration of this interval, Δt, when Δt tends towards zero,
given that the item is in an up state at the start of the time interval
Note 1 to entry: For applications where distance travelled or number of cycles of operation is more relevant than
time then the unit of time can be replaced by the unit of distance or cycles, as appropriate.
Note 2 to entry: The term “failure rate” is often used in the sense of “mean failure rate” defined in IEV 192-05-07.
[SOURCE: IEC 60050-821:FDIS2016]
3.24
fault,
abnormal condition that could lead to an error in a system
Note 1 to entry: A fault can be random or systematic.
[SOURCE: IEC 60050-821:FDIS2016, 821-11-20]
3.25
function,
specified action or activity which can be performed by technical means and/or human beings and has a
defined output in response to a defined input
Note 1 to entry: A function can be specified or described without reference to the physical means of achieving it.
[SOURCE: IEC 60050-821:FDIS2016, 821-12-25, modified]
3.26
functional safety
part of the overall safety that depends on functional and physical units operating correctly in response to
their inputs
[SOURCE: IEC 60050-351, 351-57-06]
3.27
generic product
product independent of applications, fulfilling predefined boundary conditions, interfaces and
functionality (black box)
EXAMPLE: Examples point machines, axle counters, real-time operating systems, fail-safe computer platform
without application software.
[SOURCE: IEC 60050-821:FDIS2016, 821-01-57]
3.28
hazard
condition that could lead to an accident
Note 1 to entry: The equivalent definition in [IEC 60050-903:2013, 903-01-02] refers to "harm" instead of
"accident".
3.29
hazard analysis
process of identifying hazards and analysing their causes, and the derivation of requirements to limit the
likelihood and consequences of hazards to a tolerable level
Note 1 to entry: Similar process aspects are also considered in risk assessment. In this standard the term is
applied in life cycle phases after “requirements specification”.
[SOURCE: IEC 60050-821: FDIS2016, 821-11-23]
3.30
hazard log
document in which hazards identified, decisions made, solutions adopted and their implementation
status are recorded or referenced
[SOURCE: IEC 60050-821:FDIS2016, 821-12-27]
3.31
hazard rate
rate of occurrence of a hazard
Note 1 to entry: For detailed mathematical understanding of "rate" refer to the definition of "failure rate".
3.32
implementation
activity applied in order to transform the specified designs into their realization
[SOURCE: IEC 60050-821:FDIS2016, 821-12-29, modified]
3.33
independent safety assessment
process to determine whether the system/product meets the specified safety requirements and to form a
judgement as to whether the system/product is fit for its intended purpose in relation to safety
Note 1 to entry: Requirements for independence are defined in this European Standard.
3.34
individual risk
risk, resulting from e.g. a product, process or system, to which an individual person is exposed
Note 1 to entry: Individual risk is not to be confused with risk of single victim accidents.
Note 2 to entry: Collective risk is the sum of the individual risks to those individuals in the population or group.
However, the collective risk divided by the number of individuals will only provide the average individual risk.
3.35
integration
process of assembling the elements of a system according to the architectural and design specification,
and the testing of the integrated unit
3.36
life cycle
series of identifiable stages through which an item goes, from its conception to disposal
EXAMPLE A typical system lifecycle consists of: concept and definition; design and development; construction,
installation and commissioning; operation and maintenance; mid-life upgrading, or life extension; and
decommissioning and disposal.
Note 1 to entry: The stages identified will vary with the application.
Note 2 to entry: In case mid-life upgrading or life extension introduce changes, this standard requires re-
consideration of the life cycle.
[SOURCE: IEC 60050-192:2015, 192-01-09]
3.37
maintainability,
ability to be retained in, or restored to, a state to perform as required, under given conditions of use and
maintenance
Note 1 to entry: Given conditions would include aspects that affect maintainability, such as: location for
maintenance, accessibility, maintenance procedures and maintenance resources.
[SOURCE: IEC 60050-192:2015, 192-01-27]
3.38
maintenance
combination of all technical and management actions intended to retain an item in, or restore it to, a
state in which it can perform as required
Note 1 to entry: Management is assumed to include supervision activities.
[SOURCE: IEC 60050-192:2015, 192-06-01]
3.39
mission
objective description of the fundamental task performed by a system
3.40
mission profile
outline of the expected range and variation in the mission with respect to parameters such as time,
loading, speed, distance, stops, tunnels, etc., in the operational phases of the life cycle
3.41
negation
enforcement of a safe state following detection of a hazardous fault
[SOURCE: IEC 60050-821: FDIS2016, 821-12-38]
3.42
negation time
time interval which begins when the existence of a fault is detected and ends when a safe state is
enforced
[SOURCE: IEC 60050-821: FDIS2016, 821-12-39]
3.43
pre-existing software
all software developed prior to the application currently in question is classed as pre-existing software
including commercial off-the-shelf software, open-source software and software previously developed
but not in accordance with this European Standard
3.44
preventive maintenance
maintenance carried out to mitigate degradation and reduce the probability of failure
Note 1 to entry: See also condition-based maintenance (192-06-07), and scheduled maintenance (192-06-12).
[SOURCE: IEC 60050-192:2015, 192-06-05]
3.45
product,
collection of elements, interconnected to form a system, a subsystem or an equipment, in a manner
which meets the specified requirements
[SOURCE: IEC 60050-821: FDIS2016, 821-12-40, specific use modified]
3.46
project management
administrative and/or technical conduct of a project, including RAMS aspects
3.47
project manager
entity that carries out project management
[SOURCE: EN 50128:2011, 3.1.21]
3.48
railway duty holder
body with the overall accountability for operating a railway system within the legal framework
Note 1 to entry: Railway duty holder accountabilities for the overall system or its parts and life cycle activities are
sometimes split between one or more bodies or entities. For example:
— the owner(s) of one or more parts of the system assets and their purchasing agents;
— the operator of the system;
— the maintainer(s) of one or more parts of th
...