Superseded by MN C 10301 v2.

0, 19/06/2020 TN 066: 2014

For queries regarding this document

standards@asa.transport.nsw.gov.au
www.asa.transport.nsw.gov.au

Technical Note
TN 066: 2014

Issued date 13 August 2014

Effective date 13 August 2014
Subject: Revised requirements for retaining structures in
ESC 302 Structures Defect Limits

This technical note is issued by the Asset Standards Authority as an update to RailCorp
standard ESC 302 Structures Defect Limits, Version 2.1.

1. Background
In June 2013, a retaining wall at Harris Park collapsed. The investigation that followed included
a review of existing engineering standards related to retaining structures. The review identified
gaps in the documentation and recommended that the engineering standards be amended.

As a result, this technical note is issued to update ESC 302 which contains requirements for
retaining structures.

Other standards that are similarly affected include the following:

 ESC 100 Civil Technical Maintenance Plan

 TMC 110 Structures Service Schedules

 TMC 301 Structures Examination

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2. Updates to ESC 302

2.1 Appendix 1 – Defect Category Limits
Insert the following at Section E after the item ‘Wingwall’:

Table 1 – Addition to Section E

Member Defect type Defect size Defect category Mandatory

repair priority
Abutments and Horizontal More than C – 24hr action Mm1
wingwalls displacement 50 mm
Rotation More than C – 24hr action Mm1
1H:20V
Cracking at More than C – 24hr action Mm1
embankment/fill 10 mm wide
behind wall crack parallel to
wall and more
than 2 m long
Earth slump or Readily visible C – 24hr action Mm1
slip at and more than
embankment/fill 2 m long
behind wall

Replace Section O with Table 2:

Table 2 – Replacement for Section O

O. Retaining Walls and Platform Walls

Member Defect type Defect size Defect category Mandatory
repair
priority
Mass concrete Crack More than C – 24hr action
walls, reinforced 10 mm wide and
concrete walls, more than 2 m
masonry walls long
(excluding More than D – Weekly
platform walls) 10 mm wide and exceedent
less than 2 m
Refer to ‘All walls long
(movement)’ for 5 mm - 10 mm E - Record
movement wide
parameters
Lateral More than C – 24hr action
dislocation 20 mm
10 mm - 20 mm E - Record
Reinforced Crack More than 5 mm C – 24hr action
concrete panels wide and more
at post and panel than 1 m long
walls More than 5 mm D – Weekly
wide and less exceedent
Refer to ‘All walls than 1 m long
(movement)’ for
2 mm - 5 mm wide E - Record

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O. Retaining Walls and Platform Walls

Member Defect type Defect size Defect category Mandatory
repair
priority
movement Lateral More than 5 mm C – 24hr action
parameters dislocation
(within panel) 2 mm – 5 mm E - Record

Reinforced Crack More than 5 mm C – 24hr action

concrete panels wide and more
at reinforced soil than 1 m long
wall
More than 5 mm D – Weekly
wide and less exceedent
Refer to ‘All walls than 1 m long
(movement)’ for
2 mm - 5 mm E - Record
movement
wide
parameters
Lateral More than 5 mm C – 24hr action
dislocation
2 mm - 5 mm E - Record
(within panel)
Lateral More than C – 24hr action
dislocation 50 mm
between panels
Wall area with
Loss of crib
unfilled cribs C – 24hr action
filling
more than 1 m2
Wall area with fill
loss more than
1 m2 (estimated
Loss of fill from face of wall)
C – 24hr action Mm1
behind wall or more than 1 m
length (estimated
from top of
embankment)
Deformed area
more than 1 m2
Local with
Concrete crib C – 24hr action
deformation misalignment
walls greater than
75 mm
Refer to ‘All walls Concrete Crushing at ≥ 3
(movement)’ for interfaces – adjacent C – 24hr action
movement Crushing interfaces
parameters
Concrete
elements –
Evidence of Any E - Record
spalling, rust
stains, etc.
Drainage
system –
D – Weekly
Evidence of Any
exceedent
ineffective
system
Vegetation
Extent ≥ 5 m2 E - Record
Growth
≥ 100 mm D – Weekly
Tree stump
diameter exceedent

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O. Retaining Walls and Platform Walls

Member Defect type Defect size Defect category Mandatory
repair
priority
Platform wall Crack More than C – 24hr action
50 mm wide
Refer to ‘All walls 10 mm – 50 mm D – Weekly
(movement)’ for wide exceedent
movement
Less than 10 mm E - Record
parameters
Platform coping Separation of Visible D – Weekly
coping from exceedent
platform Check clearances
surface and/or for possible
wall infringement
Broken edging Any D – Weekly
exceedent
All walls Horizontal More than C – 24hr action Mm1
(movement) displacement 50 mm
Rotation More than C – 24hr action Mm1
1H:20V
Cracking at More than C – 24hr action Mm1
embankment/fill 10 mm wide
behind wall crack parallel to
wall and more
than 2 m long
Earth slump or Readily visible C – 24hr action Mm1
slip at and more than
embankment/fill 3 m long
behind wall

Notes:

1. These defect limits apply to retaining walls that are not part of a bridge substructure.
Refer to Appendix 1 Section E for defect limits for bridge abutments and wingwalls.

2. The location and extent of defects shall be measured carefully (for example,
stringlines or survey) and recorded on the examination report.

3. Expert geotechnical advice shall be obtained within seven days for all defects
covered by ‘All walls (Movement)’.

4. The indicated mandatory repair priorities are the minimum response to the defect
until it has been properly assessed and confirmed that a different response is
appropriate

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3. Interpretation guides
ESC 302 is presented as a legacy RailCorp document and shall be read in conjunction with and
interpreted according to the interpretation guidelines published:

Table 3 – Interpretation guides

Reference No Title Version Issue date

TS 10762 Legacy RailCorp Standards Interpretation - 1.0 28/06/2013
Management Overview
TS 10760 Guide to interpretation of organisational role and 1.0 17/06/2013
process references in RailCorp standards
TS 10760 - SMS Interpretation guide RailCorp SMS References 1.0 17/06/2013
within RailCorp engineering standards

Authorisation
Technical content Checked and Interdisciplinary Authorised for
prepared by approved by coordination release
checked by
Signature

Name Dorothy Koukari Richard Hitch David Spiteri Graham Bradshaw

Position Senior Engineer Lead Civil Engineer Chief Engineer Rail Principal Manager
Standards Network Standards &
Services

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Engineering Standard
Structures

ESC 302

Engineering Standard
STRUCTURES DEFECT LIMITS

Version 2.1

Issued December 2009

Owner: Chief Engineer Civil

Approved by: John Stapleton Authorised by: Richard Hitch

Group Leader Standards Chief Engineer Civil
Civil

Disclaimer
This document was prepared for use on the RailCorp Network only.
RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be
sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the
copy of the document it is viewing is the current version of the document as in use by RailCorp.
RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes
any liability which arises in any manner by the use of this document.
Copyright
The information in this document is protected by Copyright and no part of this document may be reproduced, altered,
stored or transmitted by any person without the prior consent of RailCorp

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Document control
Revision Date of Approval Summary of change
2.1 December, 2009 Changes detailed in Summary table below
2.0 December, 2008 New Section 7.2 on mandatory repair priorities for bridges;
Additional defect category limits for brickwork mortar in arch
underbridges, underbridge walkways, tunnel seepage, gabion walls;
Additional details in Appendix 2 re structurally critical memberst
1.0 September, 2006 First issue as a RailCorp document

Summary of changes from previous version

Section Summary of change
Document Change of format for front page, change history and table of contents
Control
All Minor editing and formatting.

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Contents
1 Purpose, Scope and Application ............................................................................................................ 4
2 References ................................................................................................................................................ 4
2.1 Australian and International Standards ......................................................................................... 4
2.2 RailCorp Documents ..................................................................................................................... 4
2.3 Other References .......................................................................................................................... 4
3 Glossary of Terminology ......................................................................................................................... 4
4 Introduction............................................................................................................................................... 5
5 Defect Categories..................................................................................................................................... 5
6 Repair Priorities........................................................................................................................................ 6
6.1 General .......................................................................................................................................... 6
6.2 Mandatory Repair Priorities ........................................................................................................... 6
7 Paint Index ................................................................................................................................................ 6
8 Defect Limits ............................................................................................................................................. 7
9 Structurally Critical Members ................................................................................................................. 7
10 Transoms .................................................................................................................................................. 7
Appendix 1 – Defect Category Limits ............................................................................................................... 8
Appendix 2 – Structurally Critical Members .................................................................................................. 18

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1 Purpose, Scope and Application

This document specifies the defect limits and mandatory responses that apply to structures on the
RailCorp network.

They are intended to be observed and implemented by maintenance staff during the course of their
examinations of structures.

The frequency of inspections is prescribed in ESC 100 “Civil Technical Maintenance Plan” and
associated specific maintenance plans for major structures.

Procedures for the examination of structures are provided in TMC 301 “Structures Examination
Manual”.

Whilst this Standard applies from date of issue, the requirement for mandatory repair priorities
generates a backlog of maintenance works. This backlog of works is to be resourced under the
Routine Maintenance of Bridges and Structures Strategy. The backlog is to be rectified within 3
years of the date of publication of this Standard.

2 References
2.1 Australian and International Standards
Nil

2.2 RailCorp Documents

ESC 100 “Civil Technical Maintenance Plan”

TMC 301 “Structures Examination Manual”

2.3 Other References

Nil

3 Glossary of Terminology
The following terminology is used in this Standard:

Track Team Manager: Person responsible for the examination and maintenance of a
Track Length.
Bridge Examiner: Person responsible for the examination of bridges and other civil
structures.
Structures Officer: Bridge examiner with specialist skills in the examination and
preliminary assessment of steel and wrought iron bridges.
Structures Team Person with relevant technical competency in the structures
Manager: discipline. May be the Manager of Civil discipline personnel in an
area or as nominated by the Manager.
Civil Maintenance The Civil Engineering Manager of an area.
Engineer:
Defect: Deterioration of a component from its original condition.
Defect Category: Classification of a defect into a category that indicates the severity
of the defect and response time recommended for continuing train
operations and engineering assessment.
Exceedent: Any defect in the asset that requires remedial action within two
years or less.

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Non-exceedent: A defect in an asset that requires recording for future reference,

monitoring and possible remedial action outside two years.
Repair Priority: Time frame for the repair of a defect.

4 Introduction
Structures on the rail network deteriorate over time from their ‘as-new’ condition, owing to loading
cycles from trains, aging of materials and climatic factors such as the sun, wind, rain and salt air.
Defects that develop include pipes in timber members, rusting of steel members and cracking and
spalling of concrete.

Examinations are undertaken at prescribed intervals of all structures, to monitor their condition and
to measure the extent of any deterioration. The results of the examinations are also used to
prepare maintenance programmes for the repair or replacement of components.

Responsibilities for examination of structures are variously allocated to Track Team Managers,
Bridge Examiners, Structures Officers, Structures Team Managers and Civil Maintenance
Engineers. The types and frequencies of these examinations are laid down in RailCorp’s
Structures Examination Manual and Technical Maintenance Plans.

Defect Categories and Limits have been set to guide examination staff in the appropriate level of
action to be taken when examining and measuring structural members.

5 Defect Categories
The primary examinations of structures are undertaken by Bridge Examiners and Structures
Officers. They are responsible for measuring any defects and are also required to assign a defect
category. Depending on the extent of any defects found by examination staff, immediate action
may need to be taken to ensure the safety of rail traffic.

The recommendations of the examination staff must then be forwarded to the Structures Team
Manager, who must also respond as summarised in the following Table 1:

Defect Bridge Examiner/ Structures Officer Response Structures Team Manager

Category Response
EXCEEDENTS
A Immediately stop trains in the case of an Assess immediately.
underbridge, or close if an overbridge or
footbridge. Advise Structures Team Manager
immediately for further assessment.
B Immediately impose a 20km/hr speed restriction Assess the same day for
in the case of an underbridge. Advise Structures underbridges.
Team Manager immediately for further
Assess within 24 hours for
assessment. For footbridges and overbridges, the
footbridges and overbridges.
area is to be barricaded and a report provided to
the Structures Team Manager the same day.
C Report to Structures Team Manager the same Assess within 24 hours.
day for the Structures Team Manager to take
appropriate action within 24 hours.
D Report to Structures Team Manager on the Assess within 7 days.
Weekly Summary of Exceedents Form for the
appropriate action.
NON-EXCEEDENTS
E Record in bridge examination report. Assess as part of bridge
management process.
Table 1: Defect Categories

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6 Repair Priorities
6.1 General
In addition to the assignment of defect categories, an initial assessment and allocation of a repair
priority as detailed below will also be made by the Bridge Examiner or Structures Officer for
structures that they have examined.

The allocation of a repair priority by the Bridge Examiner for timber or concrete bridges is optional.

Rm1 Repair within 1 month Applies to Defect Categories A to D

Rm6 Repair within 6 months Applies to Defect Categories A to D
Ry1 Repair within 1 year Could apply to any Defect Category
Ry2 Repair within 2 years Could apply to any Defect Category
Ry5 Repair within 5 years Applies to Defect Category E only
Ryxx No repair for 5 years Applies to Defect Category E only
Mm1 Monitor monthly Applies to Defect Categories A to D
Mm3 Monitor quarterly Applies to Defect Categories A to D
Mm6 Monitor half yearly Applies to Defect Categories A to D
My1 Monitor yearly Applies to Defect Categories A to D
Axx Assess/Inspect next inspection Applies to Defect Category E only
Table 2: Repair Priorities

In assigning repair priorities, considerations such as the location of the defect, importance of the
affected member, the degradation rate, the effect of multiple defects and the operating
environment (type, speed, density of train traffic) need to be taken into account.

6.2 Mandatory Repair Priorities

For bridges, some nominated defect types shall have a mandatory repair priority and those defects
shall be repaired within the mandatory timeframe.

The nominated defect types are:

− Loose rivets & bolts in steel bridge members
− Missing or broken holding down bolts in bearing and bed plates
− Loose transom bolts
− Minor cracks and spalling in main members and decks in concrete bridges
− Blocked culverts.

The nominated defect types with a mandatory repair priority are detailed in Appendix 1.

7 Paint Index
Paint indices are to be assigned by the Bridge Examiner or Structures Officer for all steel bridges
that they examine. The indices reflect the condition of the surface coating, the order of the indices
from worst to best being P1, P2 & P3. They are defined as follows:
Paint Index P1: Paint broken down throughout. Programme to paint within 5 years.
Paint Index P2: Paint broken down locally. Patch paint as required within 2 years.
Paint Index P3: Paint in satisfactory condition.

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8 Defect Limits
Appendix 1 provides a general guide to defect limits and associated actions to be taken by
structures examination personnel. It should be noted that for specific structures, individual
Technical Maintenance Plans may override these requirements.

In general, the limits and defect sizes have been set on the basis of them being located at the most
highly stressed area of the member.

9 Structurally Critical Members

Structurally critical members are defined as members of a structure that are critical to the strength
and safety of the structure and where failure of the member could lead to catastrophic collapse.

A list of structurally critical members and the critical areas for defects in these members is provided
in Appendix 2.

10 Transoms
Definition of condition:
Failed / missing transoms Are those that are broken, missing or do not give vertical
support to the rails.
Effective transoms Transom/fastener system where the required fastenings are in
place and which provides vertical support and lateral restraint.
Restraint must allow no lateral movement of the fastenings
relative to the transom. The transom must provide gauge
restraint and must be one piece that will not separate along its
length or transversely.
Transoms must have a flat rail plate seat.
Transoms may not have more than 20% loss from any part.
A transom that can be re-drilled will become effective again. It
must have sufficient material between the rail fastenings (in the
“four foot”) to distribute the load adequately.
Ineffective transoms Transom that is not effective. Transoms with rot or holes through
which “daylight” can be seen are not satisfactory.

For the purposes of assessment ineffective transoms include those that are missing or failed.

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Appendix 1 – Defect Category Limits

APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority

A. Underbridges – Steel and Wrought Iron

For steel, wrought iron and broad flange beam underbridges items in the table are defined as follows:
Main structural members are main girders, cross girders, stringers, truss chords, diagonals and verticals,
columns, trestle legs and headstocks.
Secondary structural members are bracing, bearing/bed plates, gusset plates, bearing and web stiffeners,
tie bars etc.
An element of a member is typically a flange or web and may consist of multiple plates and/or angles.
For piers, abutments, wingwalls and reinforcement see Underbridges – Concrete
Main member New crack or More than 80mm long A - Stop trains
(excluding extension of (total if old & new)
BFBs) previously 50mm - 80mm long B - 20kph speed
assessed crack Observe under load
(total if old & new)
10mm – 49mm long B - 20kph speed
(total if old & new)
New crack 0mm-9mm long C - 24hr action
Missing Any A - Stop trains
Main member Crack at bearing More than 300mm B – 20 kph speed
zone
Less than or equal to C – 24hr action
300mm
Main member Corrosion loss Perforation to any element C - 24hr action
More than 30% section C - 24hr action
loss
10-30% section loss D - Weekly exceedent
Less than 10% section E – Record
loss
Secondary Crack Any D - Weekly exceedent
member Missing Any B - 20kph speed
Corrosion loss Perforations to any D - Weekly exceedent
element
Main Member Bolts / Rivets More than 50% A - Stop trains
Fastenings missing
(at connections) Loose More than 50% B - 20kph speed
Loose / Missing 30% to 50% B - 20kph speed
10% to 30% C - 24hr action
Up to 10% D - Weekly exceedent Ry2
Main Rivets Corroded away More than 50% of rivet C – 24hr action
in any 600mm heads
length of girder Less than or equal to 50% D – Weekly exceedent Ry2
of rivet heads

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APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority
Secondary Missing More than 50% B - 20kph speed
Fastenings Loose More than 50% C - 24hr action
Loose / Missing 30% to 50% D - Weekly exceedent
Up to 30% E - Record Ry2
Segmental Locked over - D - Weekly exceedent.
Bearings Reset but only after
structural /geotechnical
investigation into
abutment stability
Bed or Bearing Missing / Broken More than 30% D - Weekly exceedent
Plate HD Bolts Up to 30% E - Record Ry2
Bed Plate Broken D - Weekly exceedent
Bearing Pads Broken / Missing More than 25% D - Weekly exceedent
mortar Up to 25% E - Record
Flaking paint Any D - Weekly exceedent
Impact Damage
Track Out of alignment More than 50mm A - Stop trains
(bridge has 30mm – 50mm B - 20kph speed
moved)
Less than 30mm C - 24hr action
Main member Major structural Structure likely to be A - Stop trains
damage unable to carry load
Girder Flange Flange outstand More than 60% of A – Stop trains
deformed outstand width
vertically 30-60% of outstand width B – 20 kph speed
20-29% of outstand width C – 24hr action
Up to 20% of flange D – Weekly exceedent
outstand width
Flange deformed More than 60mm B - 20kph speed
horizontally 30mm – 60mm C - 24hr action
within bracing
bay 20-29mm D - Weekly exceedent
Up to 20mm E – Record
Notched More than 30mm A – Stop trains
Up to 30mm B – 20 kph speed
Trestle Column More than 100mm A - Stop trains
deformed in any 50-100mm B - 20kph speed
direction
25mm-49mm D – Weekly exceedent
Up to 25mm E – Record
Main Rivets Sheared off in More than 50% of rivets C – 24hr action
any 600mm Up to 50% of rivets D – Weekly exceedent
length of girder
Any Joint Rendered More than 50% B - 20kph speed
Fastenings ineffective Less than or equal to 50% C – 24hr action

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APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority

B. Underbridges – Broad Flange Beams

All the above limits for steel and wrought iron underbridges applies to B.F.B. underbridges except for the
“Main Girder/Truss”, “New Crack” items which are to be replaced with the following.
Unplated B.F.B. spans
BFB Flange Crack More than 25mm A - Stop trains
10-25mm B - 20kph speed &
observe under load.
Stop road traffic during
passage of each train
5-9mm B - 20kph speed
Less than 5mm C - 24hr action
Plated B.F.B. spans
Both Crack More than 25mm A - Stop trains
BFB Flange and 10-25mm B - 20kph speed &
Flange plate observe under load.
Stop road traffic during
passage of each train
5-9mm B - 20kph speed
Less than 5mm C - 24hr action
Either Crack More than 50mm A - Stop trains
BFB Flange or 20-50mm B - 20kph speed &
Flange plate observe under load.
Stop road traffic during
passage of each train
10-19mm B - 20kph speed
Less than 10mm C - 24hr action

C. Underbridges – Timber

The following maintenance limits are based on nominal 300mm x 300mm timber section
Girder/Corbel Pipe / Trough in More than 250mm A - Stop trains
any girder or 226-250mm B - 20kph speed
corbel
200-225mm C - 24hr action
151-199mm D - Weekly exceedent
50-150mm E - Record
Crushing B - 20kph speed
Solid Headstock Pipe / Trough More than 250mm A - Stop trains
226-250mm B - 20kph speed
200-225mm C - 24hr action
151-199mm D - Weekly exceedent
50-150mm E - Record
Crushing Any B - 20kph speed

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APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority
Girder Mid span Exceeds values tabulated B – 20kph speed
deflection below
Span (m) 4.27 4.57 7.32 7.92

Deflection
8 9 20 22
(mm)
Girder/Corbel Rotted out B - 20kph speed
small section
250x150mm
Waling Rotted out B - 20kph speed
Headstock
Waling Sill Rotted out C - 24hr action
Body Bolts Loose More than 25% D - Weekly exceedent
Less than or equal to 25% E - Record
Corbel bolts Loose More than 25% D - Weekly exceedent
Less than or equal to 25% E - Record
Trestle Bolts Loose More than 25% D - Weekly exceedent
Less than or equal to 25% E - Record
Piles Section loss in More than 75% A - Stop trains
more than 50%
of piles in any
trestle or
abutment
Section loss in More than 75% B - 20kph speed
more than25% of
piles in any
trestle or
abutment
Section loss in More than 75% C - 24hr action
any pile 50-75% D - Weekly exceedent
40-49% E - Record
Pumping Any D - Weekly exceedent
Decking Split or rotted out More than 20% E - Record
Any Timber Termite
Any evidence of damage C - 24hr action
Section infestation
D. Underbridges – Timber Transoms
Transoms Ineffective 3 Adjacent B - 20kph speed
2 Adjacent C - 24hr action
2 in 3 D - Weekly exceedent
One isolated E - Record
Transom Bolts Missing 3 Adjacent transoms B - 20kph speed
2 Adjacent transoms C - 24hr action
One transom (2 bolts)
D - Weekly exceedent
isolated
Loose Any E - Record Ry2

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APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority

E. Underbridges – Concrete
Main-P.S.C or Differential Visible C - 24hr action
R.C deflection
between units
under live load
Main-P.S.C Crack Other than shrinkage B - 20kph speed
(surface) crack more than
0.3mm
Main-R.C Crack More than 2mm wide C - 24hr action
0.5 - 2mmwide D - Weekly exceedent Ry2
Main Section loss in More than 30% D - Weekly exceedent
Reinforcing. Bar one bar Undertake diagnostic
testing
Stirrup Section loss in More than 60% D - Weekly exceedent
Reinforcing. one bar Undertake diagnostic
testing
Prestressing Exposed Any C - 24hr action
Ducts/Tendons
Piers/Abutments Crack More than 5mm wide & 1 C - 24hr action
metre long especially
under bearings
2-5mm wide D – Weekly exceedent
Wingwall Crack More than 5mm wide & 2 C - 24hr action
metres long
2-5mm wide D – Weekly exceedent
Lateral More than 20mm D - Weekly exceedent
dislocation
Deck Spalling More than 1 square metre D - Weekly exceedent
with exposed reinforcing Undertake diagnostic
testing
300mm x 300mm & no E - Record Ry2
reinforcing exposed Undertake diagnostic
testing
Deck – joint Fouling with Any D – Weekly exceedent
between slabs ballast/debris
Bearings Any degradation D – Weekly exceedent
Impact Damage
Main Deformation Any A - Stop trains
Main-P.S.C or Crack Other than shrinkage A - Stop trains
R.C. (surface) crack more than
0.3mm

© Rail Corporation Page 12 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1
 RailCorp Engineering Standard — Structures
Superseded by MN C 10301 v2.0, 19/06/2020 Structures Defect Limits ESC 302

APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority

F. Underbridges – Masonry and Concrete Arch

For piers, abutments, wingwalls and reinforcement see Underbridges – concrete
Arch Ring Brickwork More than 30% in any B – 20kph speed
dislocation square metre missing or
unbonded
10-30%in any square D – Weekly exceedent
metre missing or
unbonded
Longitudinal More than 3mm wide, A – Stop trains
cracking through & across full arch
(along arch width. Visible differential
barrel) movement under live load
2-3mm & not through & C – 24hr action
across
Less than 2mm & not D – Weekly exceedent
through & across
Circumferential More than 6mm wide & C – 24hr action
cracking more than 2m long along
(along arch arch
profile) 3-6mm wide, or more than D – Weekly exceedent
6mm wide and less than
2m long along arch
Distortion of More than 50mm – B - 20 kph speed
profile detectable by undulations
in top line of spandrel
walls / parapets or track
20-50mm D - Weekly exceedent
Other than Arch Brickwork More than 50% in any C - 24hr action
dislocation square metre missing or
unbonded
20-50% in any square D - Weekly exceedent
metre missing or
unbonded
Spandrel Wall Displacement Longitudinal more than C - 24hr action
30mm, or more than
20mm longitudinal +
20mm tilt
15-30mm D - Weekly exceedent
Culvert floor Heaving More than 50mm D - Weekly exceedent
25-50mm E - Record
Any other Brickwork Nil D - Weekly exceedent
dislocation
Brickwork Missing or loose More than 30% in any D – Weekly exceedent
mortar square metre missing or
loose
10-30%in any square E - Record
metre missing or loose

© Rail Corporation Page 13 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1
 RailCorp Engineering Standard — Structures
Superseded by MN C 10301 v2.0, 19/06/2020 Structures Defect Limits ESC 302

APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority
G. Culverts and Pipes
For undefined elements and reinforcement see Underbridges – concrete
Culvert Collapse Subsidence of A -Stop trains
formation/ballast
No subsidence of B - 20kph speed
formation/ballast
Blocked 50-100% C - 24hr action
30-50% D - Weekly exceedent
10-30% E - Record Ry2
Culvert Cracked barrel More than 30mm wide B - 20kph speed
10-30mm D -Weekly exceedent
Less than 10mm E - Record
Corrugated Joint Broken - D -Weekly exceedent
Metal Pipe Out of round / More than 50mm D -Weekly exceedent
distortion
Headwall / Cracked More than 50mm wide B - 20kph speed
Wingwall 10-50mm wide D - Weekly exceedent
Less than 10mm E - Record
Apron Scouring under More than 2m C - 24hr action
Any D - Weekly exceedent
Floor Heaving More than 50mm D - Weekly exceedent
25 - 49mm E - Record
Adjacent Blocked - More than 25% C - 24hr action
Waterways Geotechnical risk
site
Blocked More than 25% D - Weekly exceedent

H. Footbridges and Overbridges

In addition to the following, Underbridge defect limits also apply where applicable
Brick parapets Horizontal crack More than 3mm wide & D – Weekly exceedent
more than ½ of parapet
width & more than 2m
long
Brick parapets Vertical crack Any crack full height and D – Weekly exceedent
full width of parapet
Pedestrian Safety Aspects
The bridge and stepway maintenance triggers described are of a structural nature and intentionally do not
cover defects in walking surface finishes, ie tiles, etc. and associated anti-slip requirements
Pedestrian Missing / Broken Any B - Seal off area
Barriers Missing / Any B - Seal off area
Displaced chain
wire infill
Missing vertical Any B - Seal off area
balusters

© Rail Corporation Page 14 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1
 RailCorp Engineering Standard — Structures
Superseded by MN C 10301 v2.0, 19/06/2020 Structures Defect Limits ESC 302

APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority
Missing Any B - Seal off area
displaced metal
sheet
Loose Any D - Weekly exceedent
Missing bolts Any D – Weekly exceedent
Traffic Barriers Missing / Broken Any C - 24hr action
/ Loose
Deck Walkway planks Broken, decayed, missing B - Seal off area
or displaced
Cracks in AC/FC Any B - Seal off area
sheets
Deck-Nails, Protrusion above More than 10mm C - 24hr action
Screws deck Less than or equal to D - Weekly exceedent
10mm
Safety Screens Missing / Broken Any B - Seal off area

Safety Screen Defective More than 50% C - 24hr action

Fixings 25-50% D - Weekly exceedent
Timber Railing, Section loss More than 25% D - Weekly exceedent
Posts
Protection Missing / Broken Any D - Weekly exceedent
Screens / Loose
Missing bolts Any D – Weekly exceedent
Stepways (also includes balustrade and handrail references above)
R.C. Stepway Broken front More than 150mm long x C - 24hr action
Tread edges 35mm deep
More than 50mm long x D - Weekly exceedent
15mm deep
Cracked More than 2 mm wide D - Weekly exceedent
R.C. Stepway Cracked More than 2 mm wide D - Weekly exceedent
Landing Less than 2 mm wide E - Record
Stepway Protruding at toe Any C - 24hr action
Reinforcing
Stepway Tread Rocking between More than 5mm C - 24hr action
heel and toe 2-5mm D - Weekly exceedent
Slope heel to toe More than 15mm D - Weekly exceedent
5-15mm E - Record
I. Underbridge walkways and refuges
Walkway & Missing / Broken Any B - Seal off area
Refuge
Handrails
Walkway & Broken, Any B - Seal off area
Refuge Planks decayed,
displaced or
missing

© Rail Corporation Page 15 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1
 RailCorp Engineering Standard — Structures
Superseded by MN C 10301 v2.0, 19/06/2020 Structures Defect Limits ESC 302

APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority
Walkway Loose or missing Any D – Weekly exceedent
fastenings
J. Underbridge guardrails
Guardrail Missing - D - Weekly exceedent
Undersize - D - Weekly exceedent
Vee section Missing / End not - D - Weekly exceedent
closed
Fastenings Missing / Loose - D – Weekly exceedent
K. Underbridge road/pedestrian safety aspects
Clearance signs Missing - D - Weekly exceedent
Not legible - D - Weekly exceedent
Ballast Falling - C - 24hr action
L. Underbridge Ballast Logs/Walls
Ballast Log Missing / Rotted - D - Weekly exceedent
out
Ballast Wall Decayed, - D - Weekly exceedent
displaced or
missing
M. Overhead Wiring Structures and Signal Gantries
Structural Corrosion loss Perforation to any element C – 24hr action
member More than 20% section D - Weekly exceedent
loss
Loose / Missing Any D - Weekly exceedent
bolts
Masts or portal Leaning off More than 50mm from D - Weekly exceedent
structure vertical design
Guy foundation Dislodged - D - Weekly exceedent
N. Tunnels
Roof/Wall Brickwork More than 30% in any C – 24hr action
dislocation square metre missing or
unbonded
10-30% in any square E - Record
metre missing or
unbonded
Longitudinal More than 5mm wide & B - 20kph speed
cracking more than 5m long
(along tunnel) 2-5mm & more than 5m C – 24hr action
long
Less than 2mm & more D - Weekly exceedent
than 5m long
Circumferential More than 5mm wide & D - Weekly exceedent
cracking more than 2m long along
(along tunnel tunnel profile
profile) More than 5mm wide & E - Record
less than 2m long along
tunnel profile

© Rail Corporation Page 16 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1
 RailCorp Engineering Standard — Structures
Superseded by MN C 10301 v2.0, 19/06/2020 Structures Defect Limits ESC 302

APPENDIX 1: DEFECT CATEGORY LIMITS

Mandatory
Member Defect Type Defect Size Defect Category
Repair Priority
Spalling Through the lining or of D - Weekly exceedent
whole bricks
Seepage Causing corrosion of track D - Weekly exceedent Ry1
fastenings
Any E - Record
Portal Crack More than 50mm wide B - 20kph speed
10-50mm wide D - Weekly exceedent
Less than 10mm E - Record
O. Retaining Walls and Platform Walls
Retaining wall Crack More than 10mm wide & C - 24hr action
more than 2 metres long
More than 10mm wide & D -Weekly exceedent
less than 2 metres long
5-10mm wide E - Record
Lateral More than 20mm C - 24hr action
dislocation 10-20mm E - Record
Platform wall Crack More than 50mm wide C - 24hr action
10-50mm wide D - Weekly exceedent
Less than 10mm E - Record
Platform coping Separation from Visible D - Weekly exceedent
platform surface Check clearances for
and/or wall possible infringement
Broken edging Any D - Weekly Exceedent
P. Gabion Walls
Gabion baskets Damaged Loss of tension/Rocks D - Weekly exceedent
- bridges spilling out
Lateral More than 100mm D – Weekly exceedent
dislocation

© Rail Corporation Page 17 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1
 RailCorp Engineering Standard — Structures
Superseded by MN C 10301 v2.0, 19/06/2020 Structures Defect Limits ESC 302

Appendix 2 – Structurally Critical Members

A. Steel and wrought iron underbridges

Span Type Structurally Critical Details of Critical Areas

Member

Plate web deck, Main girders Bottom flange: middle third of span
RSJ and BFB
Top flange: over intermediate piers and buckling at
mid spans
Web splices: middle half of span
Web: at support
Plate web Main girders Bottom flange: middle third of span
through
Top flange: over intermediate piers and buckling at
mid spans
Web splices: middle half of span
Web: at support
Cross girders Bottom flange: middle half of span and end
connections
Web: at support
Stringers Bottom flange: middle half of span and end
connections
Web: at support
Trusses (Pratt) Top chord Buckling at mid-span
Bottom chord Middle half of span
Portal frames Mid-span frames at end connections
Cross girders Middle half of span and connections to bottom chords
Stringers Middle half of span and end connections
First web verticals Whole member, including connections
Internal web diagonals Whole member towards abutments

B. Timber bridges

All spans Girders Middle third (bending) and over corbels (shear)
Corbels Over headstocks (shear)
Headstocks Nil
Piles At ground level , and 500mm above and below
ground level

C. Concrete bridges

All spans Pre-Stressed Concrete Middle third of span

Girders
Over supports (shear)
Reinforced Concrete Middle third of span
Girders
Over supports (shear)

© Rail Corporation Page 18 of 18

Issued December 2009 UNCONTROLLED WHEN PRINTED Version 2.1