Wood Pole Serviceability - T HR EL 10003 ST
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T HR EL 10003 ST Standard Wood Pole Serviceability Version 2.0 Issue date: 24 June 2021 © State of NSW through Transport for NSW 2021
T HR EL 10003 ST
Wood Pole Serviceability
Version 2.0
Issue date: 24 June 2021
Important message
This document is one of a set of standards developed solely and specifically for use on
Transport Assets (as defined in the Asset Standards Authority Charter). It is not suitable for any
other purpose.
The copyright and any other intellectual property in this document will at all times remain the
property of the State of New South Wales (Transport for NSW).
You must not use or adapt this document or rely upon it in any way unless you are providing
products or services to a NSW Government agency and that agency has expressly authorised
you in writing to do so. 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. To be clear, the content of this document is not licensed under any
Creative Commons Licence.
This document may contain third party material. The inclusion of third party material is for
illustrative purposes only and does not represent an endorsement by NSW Government of any
third party product or service.
If you use this document or rely upon it without authorisation under these terms, the State of
New South Wales (including Transport for NSW) and its personnel does not accept any liability
to you or any other person for any loss, damage, costs and expenses that you or anyone else
may suffer or incur from your use and reliance on the content contained in this document. Users
should exercise their own skill and care in the use of the document.
This document may not be current and is uncontrolled when printed or downloaded. Standards
may be accessed from the Transport for NSW website at www.transport.nsw.gov.au
For queries regarding this document, please email the ASA at
standards@transport.nsw.gov.au or visit www.transport.nsw.gov.au
© State of NSW through Transport for NSW 2021T HR EL 10003 ST
Wood Pole Serviceability
Version 2.0
Issue date: 24 June 2021
Standard governance
Owner: Director Energy Networks & Systems, Asset Management Branch
Authoriser: Director Engineering, Asset Management Branch
Approver: Executive Director, Asset Management Branch on behalf of the AMB Configuration Control
Board
Document history
Version Summary of changes
1.0 First issue, 16 January 2015.
2.0 Second issue. Changes include amendment to the design loading conditions for the assessment
of unsupported poles, amendment to the factor of safety for unsupported poles, and minor
amendments and clarification to content.
© State of NSW through Transport for NSW 2021 Page 3 of 12T HR EL 10003 ST
Wood Pole Serviceability
Version 2.0
Issue date: 24 June 2021
Preface
The Asset Management Branch (AMB), formerly known as Asset Standards Authority (ASA) is a
key strategic branch of Transport for NSW (TfNSW). As the network design and standards
authority for NSW Transport Assets, as specified in the ASA Charter, the ASA identifies,
selects, develops, publishes, maintains and controls a suite of requirements documents on
behalf of TfNSW, the asset owner.
The ASA deploys TfNSW requirements for asset and safety assurance by creating and
managing TfNSW's governance models, documents and processes. To achieve this, the ASA
focuses on four primary tasks:
• publishing and managing TfNSW's process and requirements documents including TfNSW
plans, standards, manuals and guides
• deploying TfNSW's Authorised Engineering Organisation (AEO) framework
• continuously improving TfNSW’s Asset Management Framework
• collaborating with the Transport cluster and industry through open engagement
The AEO framework authorises engineering organisations to supply and provide asset related
products and services to TfNSW. It works to assure the safety, quality and fitness for purpose of
those products and services over the asset's whole-of-life. AEOs are expected to demonstrate
how they have applied the requirements of ASA documents, including TfNSW plans, standards
and guides, when delivering assets and related services for TfNSW.
Compliance with ASA requirements by itself is not sufficient to ensure satisfactory outcomes for
NSW Transport Assets. The ASA expects that professional judgement be used by competent
personnel when using ASA requirements to produce those outcomes.
About this document
This document provides the serviceability categories and the criteria for assessing wood poles
in the RailCorp HV distribution system.
This is a second issue. The changes to previous content include:
• minor amendments and clarification to content
• amendment to the design loading conditions for the assessment of unsupported poles
• amendment to the factor of safety for unsupported poles
© State of NSW through Transport for NSW 2021 Page 4 of 12T HR EL 10003 ST
Wood Pole Serviceability
Version 2.0
Issue date: 24 June 2021
Table of contents
1. Introduction .............................................................................................................................................. 6
2. Purpose .................................................................................................................................................... 6
2.1. Scope ..................................................................................................................................................... 6
2.2. Application ............................................................................................................................................. 6
3. Reference documents ............................................................................................................................. 6
4. Terms and definitions ............................................................................................................................. 7
5. General requirements ............................................................................................................................. 7
5.1. Maintenance staff .................................................................................................................................. 7
5.2. Timber pole specification ....................................................................................................................... 7
6. Serviceability categories ........................................................................................................................ 7
7. Serviceability criteria .............................................................................................................................. 8
7.1. Supported poles ..................................................................................................................................... 8
7.2. Unsupported poles ................................................................................................................................. 9
8. Risk assessment for conditionally serviceable and condemned poles .......................................... 10
9. Marking of poles .................................................................................................................................... 11
10. Records .................................................................................................................................................. 12
© State of NSW through Transport for NSW 2021 Page 5 of 12T HR EL 10003 ST
Wood Pole Serviceability
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Issue date: 24 June 2021
1. Introduction
Power supply to traction (and other) substations, railway stations, signalling systems, as well as
other elements of the TfNSW heavy rail network is primarily provided by the RailCorp high
voltage (HV) distribution system. The RailCorp HV distribution system consists of both high
voltage cables and aerial lines with nominal voltages of between 11 kV and 132 kV.
The primary support structure for RailCorp HV aerial lines is wood poles.
2. Purpose
This document sets out the serviceability categories and the criteria for assessing wood poles in
the RailCorp HV distribution system so that they are fit for purpose.
2.1. Scope
This document covers wood poles specified in T HR EL 10001 ST HV Aerial Line Standards for
Design and Construction.
Where wood poles of other timber species are encountered during pole inspections, the
serviceability criteria for such poles will be developed by the maintenance AEO and submitted
to the Director Energy Networks & Systems, AMB for approval.
2.2. Application
This document applies to wood poles supporting RailCorp HV aerial lines and stay poles that
are of timber species specified in T HR EL 10001 ST.
In addition to the requirements of this standard, asset decisions shall take into account the life
cycle cost considerations specified in T MU AM 01001 ST Life Cycle Costing.
If, when using this standard, it is considered that the intent of stated requirements is not clear, a
clarification should be sought from the Director Energy Networks & Systems, AMB.
3. Reference documents
The following documents are cited in the text. For dated references, only the cited edition
applies. For undated references, the latest edition of the referenced document applies.
Transport for NSW standards
T HR EL 10001 ST HV Aerial Line Standards for Design and Construction
T HR EL 10004 SP Timber Poles
T MU AM 01001 ST Life Cycle Costing
© State of NSW through Transport for NSW 2021 Page 6 of 12T HR EL 10003 ST
Wood Pole Serviceability
Version 2.0
Issue date: 24 June 2021
Other reference documents
ISSC 29 Guideline for Pre-Climbing and Climbing Assessment of Poles
NMD-ME-PRO-401 Corrective Maintenance Timeframes on Aerial Line Assets
Note: This document is available from Sydney Trains through the relevant contract
manager.
PR D 78000 Electrical Network Safety Rules
PR D 78701 Personnel Certifications – Electrical
4. Terms and definitions
The following terms and definitions apply in this document:
AEO Authorised Engineering Organisation
ASA Asset Standards Authority
HV high voltage; a voltage exceeding 1000 V ac or 1500 V dc
TMP technical maintenance plan
TfNSW Transport for New South Wales
5. General requirements
Section 5.1 and Section 5.2 apply to all wood pole serviceability assessments.
5.1. Maintenance staff
All inspections of wood poles shall be done by maintenance staff suitably authorised in
accordance with PR D 78701 Personnel Certifications – Electrical.
All HV aerial line maintenance staff working on or near the TfNSW heavy rail electrical network
shall comply with the requirements of PR D 78000 Electrical Network Safety Rules.
5.2. Timber pole specification
Refer to T HR EL 10004 SP Timber Poles for the range of timber poles used in RailCorp’s HV
aerial line network.
6. Serviceability categories
Wood poles in RailCorp’s HV distribution system are maintained in accordance with the
electrical technical maintenance plan (TMP). The condition of a pole is assessed through
external and internal examination at, above and below ground levels.
© State of NSW through Transport for NSW 2021 Page 7 of 12T HR EL 10003 ST
Wood Pole Serviceability
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Issue date: 24 June 2021
Typical external indicators of pole degradation include, but are not limited to the following:
• mature fungal fruiting - usually associated with internal white or brown rot
• shaggy external appearance and missing pole cap - usually associated with advanced
white rot accelerated by water ingress
• knot holes, checks and splitting that allow the ingress of moisture and promote the growth
of fungal decay
• excessive cracking and/or burns due to lightning strikes
• presence of termites in the pole and/or adjacent soils
• reduction in pole diameter
The extent of internal defect is determined through internal examination of the pole.
From the results of the examinations and assessment, wood poles are classified into one of the
serviceability categories shown in Table 1 along with the corresponding actions required for
each category.
Table 1 - Wood pole serviceability categories
Serviceability category Actions
Serviceable No further action until next routine assessment.
Mark the pole in accordance with Section 9.
Conditionally serviceable Carry out a risk assessment and resultant mitigation measures
in accordance with Section 8.
Mark the pole in accordance with Section 9.
Condemned Carry out a risk assessment and resultant mitigation measures
in accordance with Section 8.
Mark the pole in accordance with Section 9.
Arrange to have the site protected immediately.
Dangerous Arrange for power to be removed from the feeder(s) supported
by the pole.
Arrange to have the pole supported immediately.
7. Serviceability criteria
Section 7.1 and Section 7.2 provide the serviceability criteria for supported and unsupported
poles, respectively.
7.1. Supported poles
A supported pole is one that is held in balance, and is prevented from falling in any direction, by
the arrangement of conductors and/or stay wires connected to the pole. The resultant pole top
© State of NSW through Transport for NSW 2021 Page 8 of 12T HR EL 10003 ST
Wood Pole Serviceability
Version 2.0
Issue date: 24 June 2021
force is countered by changed tensions in conductors and/or stay wires so that there is little or
no bending load at the ground line.
The serviceability of supported poles shall be determined from the minimum thickness (t) of
sound timber in the annulus of the pole.
The serviceability criteria of supported poles are given in Table 2.
Table 2 - Serviceability criteria of supported poles
Serviceability category Criteria
Serviceable t ≥ 40
Conditionally serviceable 40 > t ≥ 20
Condemned t < 20
Dangerous t < 20 and assessed to be at risk of imminent failure
Note: t = least thickness of sound timber (in mm) in the wall of the annulus of the pole.
7.2. Unsupported poles
The serviceability of unsupported poles shall be determined from the resultant Factor of Safety
(F). The Factor of Safety is the ratio of the remaining pole bending strength to the design
bending load at ground line. The design bending load at ground line shall be based on the
maximum wind and maximum weight criteria specified in T HR EL 10001 ST.
Where the Factor of Safety cannot be readily determined at the time of inspection, the
serviceability of a pole shall be determined from the remaining strength (S) as an initial
assessment. The remaining strength of a pole is calculated as a percentage of the original pole
strength.
The serviceability category of the pole shall be revised after the Factor of Safety has been
determined in the final assessment. The final assessment shall be completed within seven days
of the initial assessment. However, if the initial assessment determines that a pole is in the
dangerous category, then the final assessment shall be completed within one day.
The serviceability criteria of unsupported poles are given in Table 3.
Table 3 - Serviceability criteria of unsupported poles
Serviceability category Initial assessment criteria Final assessment criteria
S ≥ 80% F≥2
Note - Final assessment is
Serviceable not required if pole has been
classified as serviceable in
the initial assessment.
S < 80%; 2 > F ≥ 1.2
Conditionally serviceable Category to be confirmed in
final assessment
© State of NSW through Transport for NSW 2021 Page 9 of 12T HR EL 10003 ST
Wood Pole Serviceability
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Issue date: 24 June 2021
Serviceability category Initial assessment criteria Final assessment criteria
S < 80%; 1.2 > F ≥ 0.9
Condemned Category to be confirmed in
final assessment
S < 50% and assessed to be F < 0.9
Dangerous
at risk of imminent failure
8. Risk assessment for conditionally serviceable
and condemned poles
A risk assessment shall be conducted after a pole has been categorised as conditionally
serviceable or condemned.
The determination of the risk classification are set out in Table 4 for supported poles and
Table 5 for unsupported poles. Depending on the extent and magnitude of other pole
degradation indicators (see Section 6), a pole may be assigned a higher risk category after the
application of engineering assurance processes by the AEO.
Refer to NMD-ME-PRO-401 Corrective Maintenance Timeframes on Aerial Line Assets for time
to complete corrective actions of timber poles on TfNSW heavy rail network.
Table 4 - Risk categories for conditionally serviceable and condemned poles of
supported poles
Risk Serviceability criteria Location of pole
Very high Dangerous with All
t < 20, and assessed to be at risk of
imminent failure
High Condemned with All
t < 18
High Condemned with 18 ≤ t < 20 Pole may fall across railway line or
carriageway upon failure
Medium Condemned with 18 ≤ t < 20 All except as noted above
Low Conditionally serviceable with All
20 < t ≤ 30
Very low Conditionally serviceable with All
30 < t < 40
Note: t = least thickness of sound timber (in mm) in the wall of the annulus of the pole.
© State of NSW through Transport for NSW 2021 Page 10 of 12T HR EL 10003 ST
Wood Pole Serviceability
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Issue date: 24 June 2021
Table 5 - Risk categories for conditionally serviceable and condemned poles of
unsupported poles
Risk Serviceability criteria Location of pole
Very high Dangerous with All
F < 0.9
Very high Condemned with Pole may fall across railway line or
F≤1 carriageway upon failure
High Condemned with Pole is located outside of rail corridor
1< F < 1.1 and not in a remote area
High Condemned with 1.1 ≤ F < 1.2 Pole may fall across railway line or
carriageway upon failure
Medium Condemned with 0.9 ≤ F < 1.2 All locations other than those in the
High risk areas noted above
Medium Conditionally serviceable with Pole may fall across railway line or
1.2 ≤ F < 1.7 carriageway upon failure
Low Conditionally serviceable with Pole may fall across railway line or
1.7 ≤ F < 2 carriageway upon failure
Low Conditionally serviceable with All locations other than those in the
1.2 ≤ F < 1.7 Medium risk areas noted above
Very low Conditionally serviceable with All except as noted above
1.7 ≤ F < 2
Note: F = factor of safety is ratio between the remaining pole bending strength to the
design bending load at ground line.
9. Marking of poles
Conditionally serviceable, condemned and dangerous poles shall be marked in accordance with
the requirements of ISSC 29 Guideline for Pre-climbing and Climbing Assessment of Poles.
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Wood Pole Serviceability
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A conditionally serviceable pole is to be marked by a single band of at least 75 mm wide
reflective orange self-adhesive tape encircling the whole pole, and located between 2.4 m and
3.0 m above ground.
A condemned or dangerous pole shall be marked by a reflective orange self-adhesive tape as
for a conditionally serviceable pole, and by an 'X' permanently marked into the pole just below
the tape. The 'X' shall be at least 200 mm high.
10. Records
Results of pole examinations and risk assessments (for condemned and conditionally
serviceable poles) shall be recorded and maintained in the asset information system of the
maintenance AEO.
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