scope:
This standard is applicable to safety-related electronic systems
(including sub-systems and equipment) for railway signalling
applications.
The scope of this standard, and its relationship with other
CENELEC standards, are shown in Figure 1.
This standard is intended to apply to all safety-related railway
signalling systems/sub-system/equipment. However, the hazard
analysis and risk assessment processes defined in EN 50126 and this
standard are necessary for all railway signalling
systems/sub-systems/equipment, in order to identify any safety
requirements. If analysis reveals that no safety requirements exist
(i.e.: that the situation is non-safetyrelated), and provided the
conclusion is not revised as a consequence of later changes, this
safety standard ceases to be applicable.
This standard applies to the specification, design,
construction, installation, acceptance, operation, maintenance and
modification/extension phases of complete signalling systems, and
also to individual sub-systems and equipment within the complete
system. Annex C includes procedures relating to electronic hardware
components.
This standard applies to generic sub-systems and equipment (both
application-independent and those intended for a particular class
of application), and also to systems/sub-systems/equipment for
specific applications.
This standard is not applicable to existing
systems/sub-systems/equipment (i.e. those which had already been
accepted prior to the creation of this standard). However, as far
as reasonably practicable, this standard should be applied to
modifications and extensions to existing systems, sub-systems and
equipment.
This standard is primarily applicable to
systems/sub-systems/equipment which have been specifically designed
and manufactured for railway signalling applications. It should
also be applied, as far as reasonably practicable, to
general-purpose or industrial equipment (e.g.: power supplies,
modems, etc.), which is procured for use as part of a
safety-related signalling system. As a minimum, evidence shall be
provided in such cases to demonstrate either that the equipment is
not relied on for safety, or that the equipment can be relied on
for those functions which relate to safety.
This standard is applicable to the functional safety of railway
signalling systems. It is not intended to deal with the
occupational health and safety of personnel; this subject is
covered by other standards.
