TN 080: 2014
For queries regarding this document
standards@asa.transport.nsw.gov.au
www.asa.transport.nsw.gov.au
Technical Note
TN 080: 2014
Issued date
Effective date
08 October 2014
08 October 2014
Subject:
Amendment to requirements for vertical safety screens
This technical note is issued by the Asset Standards Authority to transport standard
T HR EL 08001 ST Safety Screens and Barriers for 1500 V OHW Equipment. This technical
note amends the requirements for vertical safety screens at overline bridges where protection
screens are also provided.
This amendment is applicable to new installations and modifications to existing overhead wiring
and overline bridges.
1.
Safety screens and barriers for 1500 V OHW
equipment
1.1
Vertical safety screens
In Section 7.3 Vertical safety screens, replace the sixth paragraph with the following:
Table 4 and Table 5 contain the required dimensions for vertical safety screens. Where
protection screens in accordance with section 6.4 of ESC 320 are installed on an overline
bridge, the required dimensions of vertical safety screens along the edge with protection
screens are given in Table 6.
Insert the following content after Table 5:
Table 6 shows the minimum coverage of vertical safety screens installed on an overline bridge
and along the edge with protection screens in accordance with ESC 320.
A3751379
© State of NSW through Transport for NSW
Asset Standards Authority
Page 1 of 2
TN 080: 2014
Table 6 – Minimum coverage of vertical safety screens
Coverage requirement
Minimum dimension
Vertical distance between the top of the safety screen
to any live exposed 1500 V equipment
2500 mm
Along the edge of the standing surface above
electrified tracks
2000 mm horizontally from centreline
of electrified tracks
Horizontal distance between any edge of the safety
screen to live 1500 V equipment
500 mm
Taut string distance between any edge of the safety
screen and any live 1500 V equipment
2500 mm
Authorisation
Technical content
prepared by
Checked and
approved by
Interdisciplinary
coordination
checked by
Authorised for
release
Name
Wilfred Leung
Neal Hook
John Paff
Graham Bradshaw
Position
Principal Engineer
Overhead Lines &
Cables
Lead Engineer
Electrical
A/Chief Engineer
Rail
Principal Manager
Network Standards &
Services
Signature
A3751379
© State of NSW through Transport for NSW
Asset Standards Authority
Page 2 of 2
TN 057: 2014
For queries regarding this document
standards@asa.transport.nsw.gov.au
www.asa.transport.nsw.gov.au
Technical Note
TN 057: 2014
Issued date
Effective date
08 July 2014
08 July 2014
Subject:
Guide to the application of T HR EL 08001 ST Safety
Screens and Barriers for 1500 V OHW Equipment
This technical note is issued by the Asset Standards Authority to provide guidance to transport
standard T HR EL 08001 ST Safety Screens and Barriers for 1500 V OHW Equipment. The
guidance relates to the application of the standard on the following:
•
live exposed 1500 V parts for which the clearance envelopes are applicable
•
requirements for access walkways for cleaning glass panels at railway stations
1.
Clearance envelopes
1.1
Infringement of clearance envelopes
T HR EL 08001 ST Section 6 requires that:
The clearance envelopes shall not be infringed for the full range of design temperatures and
wind conditions and under all designed electrical and mechanical loads.
This means live exposed 1500 V parts shall not come within the clearance envelopes under all
design environmental and operational conditions.
Live exposed 1500 V parts include the following:
•
overhead wiring conductors
•
overhead wiring fittings including, but not limited to, pull off arms, insulators and
conductor support fittings at overline bridges
•
train pantographs
•
other live exposed 1500 V parts on the outside of train vehicles
A3506862
© State of NSW through Transport for NSW
Asset Standards Authority
Page 1 of 4
TN 057: 2014
Factors affected by environmental and operational conditions include:
2.
•
conductor blowout
•
conductor sag
•
contact wire uplift
•
dynamic movement of train vehicles
Arrangements for access walkways for cleaning
glass panels at railway stations
T HR EL 08001 ST Section 7 requires that:
Safety screens shall be provided at locations where the clearance envelope is infringed, unless
access to such locations is restricted to suitably qualified workers by means of an ASA typeapproved locking arrangement.
At many railway stations, walkways are built for the purpose of cleaning glass panels. Safety
screens and barriers in accordance with T HR EL 08001 ST are generally not provided with
these walkways. Working on these walkways shall be carried out in accordance with the
requirements of RailSafe document SMS-06-GD-0268 Working around Electrical Equipment.
The risk of unauthorised access to such walkways shall be controlled by means of an ASA
type-approved access and locking arrangement.
2.1
Access and locking arrangement
The proposed access and locking arrangement shall be designed in consultation with
appropriate stakeholders and endorsed by the relevant design and maintenance authorised
engineering organisations (AEO), before it is submitted to the ASA for approval. Where risks to
health and safety cannot be eliminated, the design shall be supported by a risk assessment that
demonstrates that:
•
control measures are deployed in accordance with the hierarchy of control measures set
out in the Work Health and Safety Regulation 2011
•
residual risks are minimised, so far as is reasonably practicable, in accordance with the
Work Health and Safety Act 2011
2.2
Example of an access and locking arrangement that is
acceptable to ASA
A system having the physical and functional characteristics described in Section 2.2.1 and
Section 2.2.2 respectively is an example of an arrangement that is acceptable to ASA.
A3506862
© State of NSW through Transport for NSW
Asset Standards Authority
Page 2 of 4
TN 057: 2014
2.2.1
Physical characteristics
a)
Means of access
Access to the restricted area can only be via doors or gates provided with a locking mechanism.
The design of the restricted access area and associated structures is such that unauthorised
access to the area by a person of normal agility is prevented.
b)
Keys for access entry ways
Where keys are used for locking and unlocking the access doors or gates, they are of a type
that prevents unauthorised replication.
Keys are located within a cabinet in a secure area.
c)
Monitoring
Opening of the key cabinet and the access doors to the restricted area is monitored via remote
alarm indication in an appropriate control centre.
d)
Signs
Signs are provided at or near the access doors to warn of hazards inside the restricted area.
2.2.2
Functional characteristics
a)
Overhead wiring isolation
Access to the restricted area shall not be allowed until after:
•
all live exposed overhead wiring parts inside the clearance envelope of any
standing surface within the restricted area has been isolated and rail connected
•
the person in charge of electrical safety of the working party has signed on an
Electrical Permit issued for the works
b)
Issue and return of access keys
Measures must be in place to ensure that the opening of the key cabinet is controlled by
suitably authorised electrical discipline staff.
The return of the key to the cabinet at the completion of work shall be controlled by suitably
authorised electrical discipline staff, utilising a process that confirms the following:
c)
•
the Electrical Permit issued for the works has been cancelled
•
the access doors have been closed and locked
Prevention of unauthorised access during work
The person in charge of the working party must arrange for measures to prevent unauthorised
access to the restricted area while the working party has access to the restricted area.
A3506862
© State of NSW through Transport for NSW
Asset Standards Authority
Page 3 of 4
TN 057: 2014
d)
Emergency access
Procedure to allow access to the restricted area under emergency conditions shall be included
in the design.
e)
Maintenance plan
A maintenance plan shall be provided to ensure the control measures are effective throughout
the life of the assets involved.
Authorisation
Technical content
prepared by
Checked and
approved by
Interdisciplinary
coordination
checked by
Authorised for
release
Name
Wilfred Leung
Neal Hook
David Spiteri
Graham Bradshaw
Position
Principal Engineer
Overhead Lines and
Cables
Lead Electrical
Engineer
Chief Engineer Rail
Principal Manager
Network Standards &
Services
Signature
A3506862
© State of NSW through Transport for NSW
Asset Standards Authority
Page 4 of 4
T HR EL 08001 ST
Standard
Safety Screens and Barriers for
1500 V OHW Equipment
Version 1.0
Issued Date: 12 Mar 2014
Effective Date: 12 Mar 2014
Important Warning
This document is one of a set of standards developed solely and specifically for use on the rail network owned or managed by the NSW
Government and its agencies. It is not suitable for any other purpose. You must not use or adapt it or rely upon it in any way unless
you are authorised in writing to do so by a relevant NSW Government agency.
If this document forms part of a contract with, or is a condition of approval by, a NSW Government agency, use of the document is
subject to the terms of the contract or approval.
This document may not be current. Current standards are available for download from the Asset Standards Authority website at
www.asa.transport.nsw.gov.au.
© State of NSW through Transport for NSW
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Standard Approval
Owner:
Authorised by:
Approved by:
N Hook, Lead Electrical Engineer
D Spiteri, Chief Engineer
J. Modrouvanos, Director, ASA on behalf of the ASA Configuration Control Board
Document Control
Version
1.0
Summary of Change
Initial release
For queries regarding this document
standards@asa.transport.nsw.gov.au
www.asa.transport.nsw.gov.au
© State of NSW through Transport for NSW
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Preface
The Asset Standards Authority (ASA) develops controls, maintains and publishes standards and
documentation for transport assets for New South Wales, using expertise from the engineering
functions of the ASA and industry.
This document has been developed by the Chief Engineer Rail section of the Asset Standards
Authority, reviewed by a committee of TfNSW cluster representatives, and approved by the
Asset Standards Authority Configuration Control Committee.
This standard specifies the conditions under which safety screens and barriers are required in
the vicinity of 1500 V overhead wiring equipment, and sets out the requirements for such
screens and barriers.
This document supersedes previous versions of RailCorp documents EP 08 00 00 07 SP Safety
Screens for Bridges over 1500V OHW Equipment and EP 08 16 00 02 SP Safety Barriers for
OHW Structures. These RailCorp documents are withdrawn with the publication of this ASA
standard.
This standard is a first issue.
© State of NSW through Transport for NSW
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T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Table of contents
1.
Introduction .......................................................................................................................................5
2.
Purpose ..............................................................................................................................................5
2.1
2.2
Scope..................................................................................................................................................5
Application.........................................................................................................................................5
3.
Reference documents.......................................................................................................................6
4.
Terms and definitions .......................................................................................................................6
5.
Standing surfaces .............................................................................................................................8
6.
Clearance envelopes.........................................................................................................................9
6.1
6.2
Clearance envelope for standing surfaces accessible to members of the public ...................10
Clearance envelope for standing surfaces located within railway premises and
not normally accessible to members of the public .....................................................................10
7.
Protection by safety screens .........................................................................................................11
7.1
7.2
7.3
7.4
7.5
Safety screens requirements .........................................................................................................11
Horizontal safety screens...............................................................................................................12
Vertical safety screens ...................................................................................................................14
Combined horizontal and vertical safety screens .......................................................................16
Bonding of safety screens .............................................................................................................17
8.
Protection by access prevention barriers ....................................................................................18
8.1
8.2
Access prevention grille.................................................................................................................18
Barrier fence ....................................................................................................................................18
© State of NSW through Transport for NSW
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T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
1.
Introduction
1500 V dc overhead wiring (OHW) is used in the TfNSW NSW Rail Assets to transmit power to
electric trains. Where members of the public and workers may access areas that are in the
vicinity of OHW equipment, the risk of persons making contact with live exposed equipment has
to be controlled through the provision of sufficient clearance or using safety screens and
barriers.
In developing this standard, EN 50122-1:2011 was used as the primary reference. However,
the following considerations were also made:

provisions in relevant Australian standards and guides, including AS/NZS 7000:2010,
AS 2067-2008, ENA NENS 04-2006 and ENA DOC 015-2006

risk profile of the existing TfNSW network due to existing infrastructure standards and
safety management systems
2.
Purpose
The purpose of this document is to specify the conditions under which safety screens and
barriers are required in the vicinity of OHW equipment, and sets out the requirements for such
screens and barriers.
This document does not cover measures to prevent unauthorised access to the rail corridor.
2.1
Scope
This document sets out the requirements for the provision of the following:

standing surfaces directly above live exposed 1500 V

safety screens to prevent persons from contacting live 1500 V OHW equipment either
directly or through a conducting object

safety barriers to prevent unauthorised access to live 1500 V OHW equipment
This document does not cover safety barrier requirements for work in the vicinity of 1500 V
equipment. Refer to the safety management systems of TfNSW and the relevant AEO for such
requirements.
2.2
Application
This document is applicable to installation of new infrastructure.
Where modifications to existing infrastructure are undertaken, the resultant configuration shall
comply with this document.
© State of NSW through Transport for NSW
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T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
3.
Reference documents
International standards
EN 50122–1:2011 Railway applications – Fixed installations – Electrical safety, earthing and the
return circuit – Part 1: Protective provisions against electric shock
Australian standards
AS 2067–2008 Substations and high voltage installations exceeding 1 kV a.c.
AS/NZS 7000:2010 Overhead line design – Detailed procedures
AS 60529 – 2004 Degrees of protection by enclosures (IP Code)
TfNSW standards
EP 08 00 00 12 SP Level crossings – OHW requirements
EP 12 10 00 21 SP Low voltage installations earthing
EP 99 00 00 07 SP Substation fencing
ESC 320 Overbridges and footbridges
ESC 510 Boundary fences
SPC 511 Boundary fences
SPG 0706 Installation of trackside equipment
Other reference document
ENA DOC 015 – 2006 National guidelines for prevention of unauthorised access to electricity
infrastructure
ENA NENS 04 – 2006 National guidelines for Safe Approach Distances to electrical apparatus
Rail Safety National Law (NSW)
4.
Terms and definitions
The following definitions apply in this document:
access prevention barriers physical barriers designed to deter unauthorised access
ASA Asset Standards Authority
DCCB direct current circuit breaker
NSW Rail Assets Refer to the ASA Charter (www.asa.transport.nsw.gov.au) for the definition of
NSW Rail Assets
OHW overhead wiring
© State of NSW through Transport for NSW
Page 6 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
railway premises
according to Rail Safety Act 2006
(a) land (including any premises on the land) on or in which is situated any item or part of an
item of rail infrastructure; or
(b) land (including any premises on the land) on or in which is situated any over-track structure
or part of an overtrack structure, or on or in which is situated any under-track structure or part of
an under-track structure; or
(c) land (including any premises on land) on or in which documents or records required for, or
relating to, the accreditation of an accredited rail operator are kept; or
(d) freight centres or depots; or
(e) maintenance depots; or
(f) premises including an office, building or housing used in connection with the carrying out of
rail operations; or
(g) rolling stock or other vehicles associated with the railway; or
(h) workshops; or
(i) any railway track, works or other thing that is part of anything mentioned in paragraphs (e) to
(h)—
but does not include any residential premises;
Refer to the Rail Safety National Law (NSW) for the definition of railway premises
RHS rectangular hollow section
safety screens physical barriers that provide protection against direct contact with exposed
1500 V overhead wiring (OHW) equipment
SHS square hollow section
solid non-perforated design any kind of construction made of concrete, steel or other material
without any holes or gaps
taut string distance The distance between two parts measured along a taut string stretched
the shortest way between those parts
TfNSW Transport for New South Wales
UB universal beam
UC universal column
© State of NSW through Transport for NSW
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T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
5.
Standing surfaces
Standing surfaces directly above live exposed 1500 V shall be of solid non-perforated design.
Standing surfaces directly above live exposed 1500 V include overline bridges, flyovers and so
on.
The construction extent of solid non-perforated design of the standing surface is shown in
Figure 1, and shall cover the following areas as a minimum:

2000 mm horizontal from the centrelines of all electrified tracks

500 mm horizontal from any live exposed 1500 V equipment
Standing surfaces may be of other design if access is restricted to suitably qualified workers by
means of an ASA type-approved locking arrangement. The requirements for such standing
surfaces shall be determined by risk assessment of the work environment, and are not covered
by this standard.
500 mm min.
Solid-wall design
Standing surface
2000 mm min.
2000 mm min.
Overhead wiring
Track centreline
Figure 1 – Minimum extent of solid non-perforated design for standing surfaces directly
above live exposed 1500 V equipment – Plan view
© State of NSW through Transport for NSW
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T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
6.
Clearance envelopes
Protection from live, exposed 1500 V equipment is provided through clearance envelopes.
The clearance envelopes shall not be infringed for the full range of design temperature and wind
conditions and under all designed electrical and mechanical loads.
The design parameters shall be clearly stated on relevant design drawings.
For insulators directly connected to live 1500 V equipment, the required clearance is measured
from the standing surface to the dead end of the insulator.
Clearance envelopes for standing surfaces include the following:

clearance envelope for standing surfaces accessible to members of the public

clearance envelope for standing surfaces located within railway premises and not
normally accessible to members of the public
The clearance envelope for standing surfaces is illustrated in Figure 2. Live exposed 1500 V
equipment may be installed outside the clearance envelope indicated by the shaded area in
Figure 2. The clearance dimensions for each type of standing surface are defined in the
relevant section.
Figure 2 - Clearance envelope for standing surfaces – side elevation
© State of NSW through Transport for NSW
Page 9 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
6.1
Clearance envelope for standing surfaces accessible to
members of the public
The clearance envelope for standing surfaces accessible to members of the public is defined in
Figure 2, and is based on the clearances shown in Table 1. EP 08 00 00 12 SP Level Crossings
– OHW Requirements contains the maximum permissible vehicle heights on surfaces
accessible to vehicles.
Live exposed 1500 V equipment may be installed in the shaded area shown in Figure 2.
Table 1 - Minimum clearance of live exposed 1500 V equipment to standing surface
accessible to members of the public
6.2
Position
Minimum clearance for
surfaces not accessible
to vehicles
Minimum clearance for
surfaces accessible to
vehicles
Vertically above (V)
3700 mm
Maximum permissible
vehicle height + 1000 mm
Horizontal
2100 mm
2100 mm
Vertically below (B)
2500 mm
2500 mm
Clearance envelope for standing surfaces located within
railway premises and not normally accessible to members of
the public
The clearance envelope for standing surfaces located within railway premises and not normally
accessible to members of the public is defined in Figure 2 and is based on the clearances
shown in Table 2.
Live exposed 1500 V equipment may be installed in the shaded area shown in Figure 2.
This clearance envelope is only applicable to standing surfaces that are totally located within
railway premises and where boundary fences in accordance with ESC 510 Boundary Fences
and SPC 511 Boundary Fences are installed.
If the above conditions are not satisfied, the clearance envelope for standing surfaces
accessible to members of the public shall be used.
EP 08 00 00 12 SP contains the maximum permissible vehicle heights on surfaces accessible
to vehicles.
Table 2 - Minimum clearance of live exposed 1500 V equipment to standing surface
located within railway premises and not normally accessible to members of the public
Minimum clearance for
surfaces not accessible
to vehicles
Minimum clearance for
surfaces accessible to
vehicles
Vertically above (V)
3700 mm
Maximum permissible
vehicle height + 1000 mm
Horizontal
2100 mm
2100 mm
© State of NSW through Transport for NSW
Page 10 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Vertically below (B)
7.
1500 mm
1500 mm
Protection by safety screens
Safety screens shall be provided at locations where the clearance envelope is infringed, unless
access to such locations is restricted to suitably qualified workers by means of an ASA
type-approved locking arrangement.
Safety screens are not required if live exposed 1500 V equipment is located outside of the
applicable clearance envelopes.
Safety screen types include the following:
7.1

vertical safety screens

horizontal safety screen

combined vertical and horizontal safety screens
Safety screens requirements
Safety screens shall be mechanically robust.
Safety screens shall be securely mounted to ensure that the specified minimum dimensions are
maintained. Table 3, Table 4 and Table 5 provide details of the minimum dimensions for safety
screens.
The design of safety screens shall be such that it is difficult for a person of normal agility to
stand or walk on them, unless measures, such as the installation of access prevention barriers,
are in place to prevent access to the top of the screens.
The design of safety screens shall be coordinated with the design of associated structures so
that it is difficult for trespassers of normal agility to gain access to the top of the screens.
Relevant structures include bridges, railway station buildings and fences.
To minimise bonding arrangements and the risk of electrolysis, preference shall be given to
vertical safety screens over horizontal safety screens.
Related topics:

Bonding of safety screens; section 7.5

Horizontal safety screens; section 7.2

Vertical safety screens; section 7.3

Combined horizontal and vertical safety screens; section 7.4

Protection by access prevention barriers; section 8
© State of NSW through Transport for NSW
Page 11 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
7.2
Horizontal safety screens
Horizontal safety screens are provided adjacent to standing surfaces above live exposed
1500 V OHW equipment.
Horizontal safety screens shall be metallic, non-perforated, and be able to support the weight of
100 kg over each of the tracks covered by the screen.
Suitable lifting lugs shall be provided to facilitate installation and maintenance of the safety
screen.
Suitable holes shall be provided on both sides of the screen for connection to the bonding
cable.
Horizontal safety screens shall be designed so that it is difficult for a person of normal agility to
stand or walk on them. For example, the screen may be sloped at an angle of 20° with a
tolerance of ± 1°.
Table 3 contains the required dimensions of horizontal safety screens.
Figure 3 shows the minimum coverage requirements for horizontal safety screens.
Figure 4 shows the minimum taut string distance for horizontal safety screens.
Care shall be exercised by designers to ensure that the requirement for dimension 'H' in Table 3
is satisfied at locations in the vicinity of crossovers, overlaps, auxiliary feeders and feeding
arrangements.
Table 3 - Minimum coverage of horizontal safety screens
Position
Standing surface
accessible to members of
the public
Along the edge of the standing
surface
2000 mm minimum horizontally from centreline of
electrified tracks
Distance from the edge of the
standing surface
500 mm minimum horizontally
Horizontal distance from any edge
of the screen to live 1500 V
equipment (H)
500 mm minimum
Taut string distance between top
of solid barrier on standing
surface and any live 1500 V
equipment
2500 mm minimum
© State of NSW through Transport for NSW
Standing surface within
railway premises and not
normally accessible to
members of the public
1500 mm minimum
Page 12 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Figure 3 - Minimum coverage of horizontal safety screens – Plan View
Figure 4 - Minimum taut string distance for horizontal safety screens – Side Elevation
© State of NSW through Transport for NSW
Page 13 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
7.3
Vertical safety screens
Vertical safety screens are provided at standing surfaces above or adjacent to live exposed
1500 V OHW equipment.
Vertical safety screens shall be non-perforated for standing surfaces accessible to the public.
Where the standing surface is located within railway premises and not normally accessible to
members of the public, the vertical safety screen may be of mesh construction satisfying the
requirements of ingress protection rating IP2X in as detailed in AS 60529-2004.
Vertical safety screens shall be designed and constructed to prevent climbing without the use of
greater than normal agility, tools or climbing aids. Care shall be exercised by designers and
maintainers to ensure that objects that may be used as climbing aids are not present within
2000 mm of the vertical safety screens.
No gap shall exist between the vertical safety screen and the standing surface.
Where the top of the screen is within the applicable clearance envelope, it shall be designed so
that it is difficult for a person of normal agility to stand or walk on it.
Table 4 and Table 5 contain the required dimensions for vertical safety screens.
Figure 5 and Figure 6 illustrate the dimensions for vertical safety screens
Care shall be exercised by designers to ensure that the minimum horizontal and taut string
distance requirements are satisfied at locations in the vicinity of crossovers, overlaps, and
auxiliary feeders.
Table 4 - Minimum coverage of vertical safety screens installed along standing surfaces
above live 1500 V equipment
Standing surface
accessible to
members of the
public
Standing surface
within railway
premises and not
normally accessible
to members of the
public
Height of screen above standing surface
1800 mm minimum
Along the edge of the standing surface
above electrified tracks
2000 mm minimum horizontally from centreline of
electrified tracks
Horizontal distance from any edge of the
screen to live 1500 V equipment (A)
500 mm minimum
Taut string distance between any edge of
the screen and any live 1500 V equipment
(S)
2500 mm minimum
© State of NSW through Transport for NSW
2100 mm minimum
Page 14 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Table 5 - Minimum coverage of vertical safety screens installed along standing surfaces
adjacent to live 1500 V equipment
Standing surface
accessibl
members of the
public
Standing surface
within railway
premises and not
normally accessible
to members of the
public
Height of screen above standing surface
1800 mm minimum
Horizontal distance between the surface of
vertical safety screen and live 1500 V
equipment (D)
600 mm minimum
400 mm minimum
Taut string distance between the standing
surface and any live 1500 V equipment via
a vertical edge of the screen (S)
2500 mm minimum
2100 mm minimum
Taut string distance between the standing
surface and any live 1500 V equipment via
the top edge of the screen (T)
3700 mm minimum
3500 mm minimum
Figure 5- Vertical safety screen for standing surface above live 1500 V equipment – Side
Elevation
© State of NSW through Transport for NSW
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T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Figure 6 - Vertical safety screen for standing surface adjacent to live 1500 V equipment –
Side Elevation
7.4
Combined horizontal and vertical safety screens
For standing surfaces above live exposed 1500 V equipment, the taut string distance
requirement may be satisfied through providing a combination of horizontal and vertical safety
screens.
The minimum height of the vertical safety screen above the standing surface may be reduced to
1200 mm, if the minimum taut string distance requirements in Table 3, Table 4.and Table 5 are
satisfied.
The combined horizontal and vertical safety screens shall comply with all other minimum
dimensions and requirements of both horizontal safety screens and vertical safety screens.
Related topics:

Horizontal safety screens; section 7.2

Vertical safety screens, section 7.3
© State of NSW through Transport for NSW
Page 16 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
7.5
Bonding of safety screens
The specific bonding requirements for safety screens shall be determined as part of the bonding
design for the structure on which the safety screen is installed.
It is permissible for vertical safety screens not to be bonded to rail so long as a risk assessment
has been performed, and adequate mitigating factors are included into the design
Horizontal safety screen shall meet the following bonding requirements:

horizontal safety screens shall be bonded to rail via a spark gap

where a horizontal safety screen is mounted off a reinforced concrete structure, it shall be
insulated from the structure.

horizontal safety screens mounted off a reinforced concrete structure shall be
insulated from any conductive objects mounted on the structure including antithrow barriers, balustrades or handrails on overline bridges.

suitable test points shall be provided to allow the integrity of insulation across each
safety screen and the structure to be measured during construction and
maintenance.

the minimum insulation resistance between the bonding circuit and the structure,
as measured by an insulation resistance meter using a test voltage of 500 V dc for
one minute and with the bonding wires disconnected from the spark gap, shall be
1 MΩ

the minimum insulation resistance between each safety screen and the structure,
as measured by an insulation resistance meter using a test voltage of 500 V dc for
one minute and with the bonding wires disconnected from the safety screen, shall
be 10 MΩ.
The minimum insulation resistance values shall be maintained throughout the design life of the
asset. The designer shall specify the minimum values for new installations after consideration of
factors that may cause degradation of the insulation.
Factors that may cause degradation of the insulation include:

ageing of the insulation material

exposure to diesel fumes

severity of pollution at site
© State of NSW through Transport for NSW
Page 17 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
8.
Protection by access prevention barriers
Suitable access prevention barriers shall be provided where live exposed 1500 V equipment is
located outside of the clearance envelope from a standing surface accessible to the public, but
a means of unauthorised access to the live equipment is available. Means of unauthorised
access might include a climbable mast of an overhead wiring structure.
Suitable prevention barriers include:

access prevention grilles

barrier fences
Access prevention barriers are generally not required for structures located within the railway
premises where boundary fences in accordance with ESC 510 Boundary Fences and SPC 511
Boundary Fences are installed. However, access prevention barriers shall be provided if the
structure is located adjacent to a climbable boundary fence so that a person of normal agility
may gain access to live equipment by climbing the structure from the top of the boundary fence.
8.1
Access prevention grille
Access prevention grilles may be installed on structures to prevent an unauthorised person of
normal agility, climbing or traversing within the clearance envelope around live equipment.
The grille shall be located so that the climber or trespasser must pass over or through it, and to
do so must use greater than normal agility, tools or climbing aids.
Access prevention grilles shall be installed:

at a height greater than 3000 mm from ground level

at a height greater than 2400 mm from a point that may be accessed by climbing

outside a 2100 mm clearance envelope from live 1500 V OHW equipment
Overhead wiring structure masts consisting of single UC, UB, SHS or RHS sections are not
considered to be climbable.
8.2
Barrier fence
Prevention of unauthorised access to live exposed 1500 V equipment from a standing surface
accessible to the public may be achieved through the provision of intruder resistant fence in
accordance with ENA DOC 015 - 2006.
A minimum clearance of 1000 mm shall be maintained between live exposed 1500 V equipment
and any part of the fence.
Where the intruder-resistant barrier fence forms part of the rail corridor boundary fence, the
intruder resistant fence shall extend for a minimum distance of 2000 mm, along the corridor
boundary, from the means of unauthorised access.
© State of NSW through Transport for NSW
Page 18 of 19
T HR EL 08001 ST
Safety Screens and Barriers for 1500 V OHW Equipment
Version 1.0
Effective Date: 12 Mar 2014
Where the barrier fence is metallic and is located within 2000 mm of an overhead wiring
structure, suitable measures shall be provided to mitigate the touch potential hazard between
the overhead wiring structure and the fence.
© State of NSW through Transport for NSW
Page 19 of 19