ESC 310 - Underbridges

Technical Note - TN 042: 2017


Subject: Changes to durability requirements arising from the publication of T HR CI 12002 ST Durability Requirements for Civil Infrastructure

Issued date: 17 October 2017

Effective date: 17 October 2017

For queries regarding this document [email protected]

www.asa.transport.nsw.gov.au

This technical note is issued by the Asset Standards Authority (ASA) to notify that the durability

requirements for civil infrastructure contained in the following documents have been superseded.

• ESC 310 Underbridges

• ESC 340 Tunnels

• T HR CI 12030 ST Overbridges and Footbridges

• T HR CI 12040 ST Overhead Wiring Structures and Signal Gantries

• T HR CI 12060 ST Retaining Walls

• T HR CI 12065 ST Station Platforms

• T HR CI 12070 ST Miscellaneous Structures

• T HR CI 12072 ST Track Slabs

• T HR CI 12130 MA Track Drainage

• T HR CI 12130 ST Track Drainage

Durability requirements are now contained in T HR CI 12002 ST Durability Requirements for Civil

Infrastructure.

© State of NSW through Transport for NSW 2017 Page 1 of 2

mailto:[email protected]


http://www.asa.transport.nsw.gov.au/


Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Date

Name Richard Hitch Richard Hitch Jason R Gordon Jagath Peiris

Position Lead Civil Engineer Lead Civil Engineer Chief Engineer Director Network Standards and Services

© State of NSW through Transport for NSW 2017 Page 2 of 2

TN 027: 2015

Technical Note TN 027: 2015

Subject: New underbridges, track structure requirements, drainage and waterproofing and derailment containment devices

Issued date: 1 May 2015

Effective dates:1 May 2015

For queries regarding this document [email protected]

www.asa.transport.nsw.gov.au

This technical note is issued by the Asset Standards Authority (ASA) as an update to RailCorp

standard ESC 310 Underbridges, Version 2.2.

This technical note supersedes TN 046: 2014 Update to RailCorp standard ESC 310

Underbridges.

TN 046: 2014 is withdrawn with the publication of this technical note, TN 027: 2015.

This technical note relates to underbridge deck types and joints, drainage, waterproofing and

includes information on derailment containment devices from TN 046: 2014.

Section 6.1 of ESC310 requires new bridge decks to be structurally continuous and does not

permit the use of jointed bridge decks. In many instances, segmental bridge decks may be

designed to behave structurally continuous, and to prevent debris from penetrating the bridge

deck.

The requirements for structurally continuous decks, deck drainage and waterproofing have been

revised.

Derailment containment devices are specified in ESC 310 in Section 4.1 New underbridges and

Section 14 Guardrails.

The derailment containment devices mentioned in the above sections are as follows:

• secondary structural elements to accommodate derailed vehicle collision loading for through

spans

• guardrails and concrete upstands which are located between the running rails

© State of NSW through Transport for NSW Page 1 of 11


http://www.asa.transport.nsw.gov.au/

TN 027: 2015

Recent studies relating to derailment risk have indicated that it is possible to reduce the number

of locations where guardrails are required to be installed and also that alternative containment

devices may be considered. The current implementation of the automatic train protection (ATP)

program has identified that concrete upstands may cause problems when located where ATP

balises are installed.

The requirements for derailment containment devices have therefore been revised.

4.1. New underbridges Delete paragraph four of Section 4.1 in ESC 310 and replace with the following:

When designing through spans, deflection barriers shall be incorporated in the structure to

accommodate potential collision loading from a derailed train in accordance with the requirements

set down in AS 5100. These are required in order to protect the main structural elements of the

bridge from damage. Refer to Section 14 for further requirements.

6. Track structure requirements Delete the contents in Section 6 of ESC 310 and replace with the following revised requirements:

6.1. General The track structure for a new underbridge or replacement underbridge shall be either ballast top

or direct fixation. The preferred configuration is a ballast top underbridge. Transom top bridges

shall only be used where there are special conditions that prevent the use of ballast top or direct

fixation subject to the approval of the Lead Civil Engineer, ASA.

Mechanical rail joints are not permitted on bridges. Anchoring of track and provision for expansion

switches shall be in accordance with Section 5.8 of ESC 220 Rail and Rail Joints.

The noise emitted from the underbridge should be the same level (within ±2 dBA) as that emitted

from the track on the approach and departure from the bridge. This requirement applies to

bridges in urban areas only. Ballasted track and direct fixation track on a concrete deck are

deemed to meet this requirement.

6.2 Bridge deck details The preferred configuration of bridge superstructure is one that provides a jointless deck within

each span. That is, without gaps or non-structural joints in the transverse or longitudinal direction

within the span. A compliant example is the typical arrangement of precast contiguous planks or

spaced beams and girders, both with a composite cast in situ concrete deck slab.

All bridges where the construction of the bridge is not unduly affected by the need to

accommodate railway operational requirements shall have jointless decks.

For bridges where a jointless deck cannot be achieved for practical reasons, for example,

limitations on construction time arising from rail operational requirements, or restricted access


TN 027: 2015

precluding the use of heavy lift cranes; alternative deck configurations may be adopted subject to

approval of the Lead Civil Engineer, ASA.

Alternative arrangements subject to approval include decks comprised of precast girders placed

side by side and connected by untensioned transverse tie bars. Non-structural joints can be

provided between sections of jointless bridge deck supporting individual tracks subject to

approval of the Lead Civil Engineer, ASA.

Bridge decks comprised of individual concrete beams that are transversely stressed together by

fully grouted high tensile steel bars or tendons to behave in a structurally monolithic manner, and

with fully grouted vertical joints between the beams, are considered to be jointless decks.

The concept development stage of all underbridge projects shall specifically address the issue of

deck jointing and if joints are proposed, shall include a justification of the deck arrangement.

All gaps and joints in decks shall be protected against ballast ingress by a durable protective

covering such as a ballast mat. Refer to Section 7.3 for requirements. Joints between spans,

including at the kerbs, shall be provided with suitable metal cover plates.

The minimum characteristic compressive concrete strength (f’c) for bridge deck concrete shall be

40 MPa.

6.3. Ballast top Ballast top underbridges are preferred to direct fixed and transom top due to ease in maintaining

the track and provide for a significant reduction in track degradation adjacent to bridge ends.

Specific component configuration requirements exist for guardrails, walkways, handrails and

refuges and bridge ends, as detailed in this design standard.

The distance between the inside face of the ballast kerb and centre line of track shall be no less

than 2150 mm.

The height of the kerb shall not be less than 600 mm. On superelevated track, a wider deck or

higher kerb may be required to ensure that ballast is fully retained on the bridge. Ballast shall not

spill onto underbridge walkways. When assessing the required height of ballast kerbs, it shall be

assumed that the ballast profile extends horizontally from the end of the sleepers. The kerbs shall

also allow for a future track lift of 100 mm and a minimum ‘freeboard’ of 50 mm above final ballast

level.

6.4. Direct fixation Direct fixation of the track to bridge decks may be considered where constraints such as limited

vertical clearances exist below or above the track.

Direct fixation shall only be adopted subject to approval of the Lead Civil Engineer, ASA.

Direct fixation track shall only be installed on jointless bridge decks, or as approved by the Lead

Civil Engineer, ASA.


TN 027: 2015

Direct fixation bridge decks shall be regarded as track slabs and shall also comply with ESC 362

Track Slabs.

Direct fixation bridges shall generally have concrete upstands to prevent a derailed train from

falling over the side of the bridge. The upstands shall comply with the requirements set out in

Section 4.1 and Section 14 of this technical note.

If compliant concrete upstands are not provided, direct fixation bridges shall have guard rails in

accordance with Section 14.3. In any case, a kerb with minimum height of 200 mm, shall be

provided at the outer edges of the deck.

Track fastenings shall be approved fastenings for track slabs in accordance with ESC 230

Sleepers and Track Support. Approved rail support plates accommodating both running rail and

guard rail are permitted.

The maximum height of grout bed under the rail fixings shall be 60 mm and the minimum shall be

20 mm. For thicknesses less than 20 mm, grout can be replaced with HDPE packers.

Where the hog of the girders or track grading results in a gap under the rail greater than 60 mm

high, packers may be used but they shall provide for full lateral restraint to the holding down bolt.

High impact epoxy grouts/mortars or specially developed grouts are to be used under the rail

plates on direct fixation bridge decks to accommodate the high dynamic effects and movement of

the deck. There shall be no metallic elements in the epoxy. Standard cementitious grouts shall

not be used.

The grout bed shall provide sufficient edge distance to the bolt to avoid cracking of the grout.

The transition from ballasted track to the direct fixation bridge deck shall be designed to ensure a

smooth transition. Some structural configurations are detailed in Section 15 of ESC 310.

6.5. Transom top Transom top bridges shall not be used for new or replacement bridges. If a transom top bridge is

proposed for a particular site, then approval of the Lead Civil Engineer, ASA shall be obtained

before design commences.

Specific component configuration requirements exist for guardrails, walkways, handrails and

refuges and bridge ends, as detailed in ESC 310.

The design of transoms shall be in accordance with the details provided in Section 16 of

ESC 310.


TN 027: 2015

7. Deck drainage and waterproofing Delete the contents in Section 7 of ESC 310 and replace with the following revised requirements:

7.1. Deck drainage Drainage of bridge decks shall generally comply with the requirements of T HR CI 12130 Track

Drainage. The drainage system shall be cleanable. The minimum pipe size shall have a diameter

of 225 mm.

Drainage systems shall not be installed within the ballast profile.

Drainage systems shall be designed to capture the water and drain it away from the track

structure at the bridge end.

Collection and disposal of water from bridge decks shall be considered when developing bridge

deck arrangements. Jointless bridge decks shall incorporate crossfall to ensure that water is

drained away from the track centreline and collected at the edges of the deck.

Where the bridge span crosses over areas accessed by the public, such as roadways and

footpaths, the deck shall be treated so that water is prevented from passing through the deck

onto the area below. This is best achieved by a jointless deck. Decks with joints shall require a

waterproofing membrane.

Bridges with decks with joints, crossing over areas not accessed by the public, such as

waterways or farmland, need not be sealed against passage of water unless required by project

specific environmental considerations.

7.2. Deck waterproofing Waterproofing membranes shall not be provided for jointless decks.

Where a cast in situ concrete deck slab is used, a special purpose waterproofing admixture

complying with AS 1478.1 Chemical admixtures for concrete, mortar and grout - Admixtures for

concrete and formulated to block concrete pores and capillaries and seal cracks shall be added to

the slab concrete. The top cover to the steel reinforcement shall be increased by 5 mm over

AS 5100 minimum requirements to improve durability. Where this is not practicable for a

proposed deck type, alternative arrangements to provide equivalent deck durability shall be

developed.

Waterproofing membranes shall be provided with a durable protective covering such as a ballast

mat.

The selection of waterproofing membranes for bridge decks with joints shall take into account

specific project conditions. Waterproofing membranes shall have a proven minimum service life of

20 years in conditions comparable to the project conditions.


TN 027: 2015

7.3. Protective coverings The selection of protective coverings for waterproofing membranes and deck joints shall take into

account project conditions. Protective coverings shall have a proven minimum service life of

20 years in conditions comparable to the project conditions.

Ballast mats shall not be installed on jointless decks unless required for noise control or track

reasons.

Ballast mats shall comply with the requirements set out in Table 5 contained in ESC 240 Ballast.

14. Derailment containment devices Delete Section 14 Guard Rails and replace with the following:

14.1. Functional purpose The purpose of derailment containment devices is to prevent a high consequence event such as

a train falling off a bridge or impacting a vulnerable structure, rather than to avoid a derailed train

fouling an adjacent track.

The prime function of derailment containment devices on underbridges is to keep derailed or

derailing bogies/wheels tracked parallel to and in close proximity to the running rails.

In the case of through spans (that is, spans where the primary structural elements such as

girders, trusses or suspension cables extend above bridge deck level), the derailment

containment devices are intended to prevent impact with key structural supporting elements.

Approved configurations for derailment containment devices are as follows:

• guardrails (in single and twin arrangements)

• deflection kerbs (that is, kerbs at edge of the bridge deck to contain derailed vehicles)

• deflection barriers (that is, secondary structural elements to protect through spans from

derailed vehicles)

Concrete upstands located between the running rails are not permitted.

14.2. Installation policy Derailment containment devices shall be installed on the following underbridges:

• through spans

• transom top spans

• ballast top and direct fix bridges over 20 m in length

For other ballast top and direct fix bridges, derailment containment devices shall only be provided

where the consequences of derailment are significant, for example where the bridge is over

standing water or a suburban road.


TN 027: 2015

Derailment containment devices are not required on inner tracks on multiple track ballast top and

direct fix bridges with full width decks capable of supporting a derailed train, for example if such a

bridge has three tracks, the centre track does not require derailment containment devices.

Where the hazard only exists on one side of the track, derailment containment devices can

generally be provided for that side only, subject to conditions below:

• Twin guardrails can be installed where the hazard only exists on one side of the track if

alternative derailment containment arrangements are not appropriate.

• On single track bridges, containment devices are required to protect both sides.

• Single guardrails are only approved for direct fix spans.

Only one form of derailment containment device shall be installed at a bridge, except that

guardrails together with deflection barriers shall be installed at transom top through spans.

The table below shows approved arrangements with reference to span type:

Structure type Single guardrails

Twin guardrails Deflection kerbs Deflection barriers

Through spans Not approved Approved for transom top spans

Not approved Approved

Transom top spans

Not approved Approved Not applicable Approved for through spans

Ballast top spans

Not approved Approved Approved Approved for through spans

Direct fix spans Approved Approved Approved Approved for through spans

14.3. Deflection kerbs – configuration details Deflection kerbs shall be detailed as follows:

a) The top of the kerb shall be 200 mm minimum above the top of the near rail.

b) The kerb shall be designed for a 250 kN horizontal point load applied at the top of the kerb at

any angle acting away from the track centre line. An ultimate load factor of 1.0 shall be used.

c) The kerbs shall extend onto the approach slabs for 3 m minimum on the approach side.

d) The kerbs shall be located to provide track clearances specified for Normal Structure Gauge

1994 in ESC 215 Transit space except that the trackside face of the kerbs shall be set to

2300 mm minimum from the track centre line so that the back of the ‘offside’ wheel of a

derailed train will be restrained by the rail before the ‘nearside’ wheel strikes the kerb.

e) The trackside face of the kerb shall be vertical.

f) There shall be no reduction in the nominated loads when live loads less than 300 LA are

adopted.


TN 027: 2015

14.4. Deflection barriers - configuration details Deflection barriers shall be detailed as follows:

a) The top of the barrier shall be at the lower of i) the height of the primary structural element

that it is to protect or ii) 1.7 m above rail level.

b) The barrier shall be designed for a 500 kN horizontal point load applied at the top of the

barrier at any angle acting away from the track centre line and in accordance with

Clause 10.4.4 of AS 5100.

c) The barriers shall extend onto the approach slabs for 3 m minimum on the approach side

and shall be detailed to protect the end of the primary structural element from impact by

derailed vehicles.

d) The barriers shall be located to provide track clearances specified for Normal Structure

Gauge 1994 in ESC 215 or increased clearances as required for the provision of walkways,

refuges and handrails.

e) Walkways, refuges and handrails shall be provided in accordance with Section 13 of

ESC 310. Note that this requirement will need to be considered when determining the

location of barriers.

f) The barrier may be a concrete barrier or a steel post and rail barrier. The barrier may be

integral with the primary structural element where the primary structural element and the

barrier consist of concrete.

g) The face of the barrier shall be detailed to minimise the possibility of a derailed vehicle

'catching' (example, by providing a smooth and solid impact surface).

h) Where the barrier is a steel post and rail barrier, the barrier shall be supported on a concrete

plinth with trackside details as for a deflection kerb.

i) The trackside face of the primary structural element shall be at least 300 mm behind the

trackside face of the protection barrier except where the barrier is integral with the primary

structural element.

j) The protection barrier shall not impede examination and maintenance of the spans.

k) Primary structural elements that extend more than 1.7 m above rail level shall be designed

for collision loads in accordance with Clause 10.4.4 of AS 5100.

There shall be no reduction in the nominated loads when live loads less than 300 LA are adopted.


TN 027: 2015

14.5. Guardrails

14.5.1. Configuration details The normal arrangement is two parallel guardrails (twin guardrails) with a tapered vee section on

the train approach side. Standard details for single guardrail installations have not been

developed at this stage. Details for single guardrail installations shall be approved by the Lead

Civil Engineer, ASA.

Guardrail installations shall comply with the following requirements:

a) Guardrail shall be new rail manufactured to AS 1085.1 or recycled rail Category 1 (white rail)

in accordance with ESC 220.

b) Guardrail section shall be the same as the running rail or one section size less than the

running rail.

c) Top of guardrail shall be no higher than the adjacent running rail and no more than 50 mm

below the running rail.

d) Each guardrail shall be plated and fastened on both sides at the same spacing as the

running rail fasteners. ‘A-Clips’ shall be used for fastening guardrails due to their higher

resistance to lateral loads.

e) A tapered nose section (vee) shall extend for a minimum of 3.6 m beyond the abutment on

the train approach side of the bridge.

f) Rails shall extend parallel for a minimum of 3 m beyond the abutment on the train departure

side of the bridge.

g) Rails shall extend parallel for a minimum of 3 m beyond the abutment on the train approach

side of through bridges.

h) Where traffic is bi-directional, the tapered guardrail section shall be installed at both ends of

the bridge.

i) Clearance between gauge face of running rail and adjacent face of guardrail shall be

380 mm.

j) Block-out holes for guardrail fastenings in concrete sleepers shall be grouted with an

approved high strength grout.

The standard guardrail drawings that are listed below are available and show dimensional set out,

detail and sizes of componentry, and fixing details for double guardrails:

• CV0179048 – Guard Rails Installation of Guard Rails on Ballast Top Underbridge General

Arrangement

• CV0179049 – Guard Rails Installation of Guard Rails on Transom Top Underbridge General

Arrangement


TN 027: 2015

• CV0179150 – Guard Rails Installation of Guard Rails on Ballast Top Underbridge Details of

Guard Rail Concrete Sleepers

• CV0179151 – Guard Rails Installation of Guard Rails on Ballast Top and Transom Top

Underbridges Detail of Tapered Nose Section

• CV0558906 - Combined ALT 1 + Guard Rail – Typical Details

14.5.2. Special installations Where expansion joints exist, specific design details of guardrail installations will be required.

Approved track fastenings shall be used.

Where noise and vibration limiting track fastenings are used on the bridge, special guardrail

sleepers shall be used for the vee.

Details of special guardrail sleepers are shown on the following drawings:

• CV 0168626 Guard Rail – Special Arrangement for Bridges Fitted with “Alternative 1” Plates

General Arrangement

• CV0168627 Guard Rail – Special Arrangement for Bridges Fitted with “Alternative 1” Plates

Details of Concrete Sleepers

• CV0168632 Guard Rail – Special Arrangement for Bridges Fitted with “Alternative 1” Plates

Details of Guard Rail Nose

14.5.3. Joints in guardrails Joints in guardrails shall be minimised. Every joint shall be plated and bolted.

If standard fishplates are used, six bolts are required.

If modified fishplates are used, all the four bolts shall have the nuts on the inside. Fishplates shall

be modified by machining, not by oxy-acetylene cutting. The plates shall have slotted holes for

the bolts.

No joints, other than insulated joints, are permitted in the vee.

14.5.4. Signalling interface Suitable isolation arrangements shall be made, where required, in track circuited and electrified

areas.

The tapered nose section (vee) is to be insulated with an approved component. One insulated

joint is required. There are three options for locating the insulated joint – built into the vee section;

immediately behind the vee section; or located at a short distance from the vee section - refer to

the standard guardrail drawings for details. This insulation requirement applies to new

installations and where refurbishment of the guardrails is undertaken.


TN 027: 2015

Where guardrails exceed 50 m in length, additional insulation and bonding arrangements may be

required. Design drawings shall specify that insulation and bonding arrangements shall be in

accordance with the requirements of the Lead Signals and Control Systems Engineer, ASA. For

further information, refer to ESG 100.17 Signal Design Principles Track Circuits.

14.5.5. Automatic train protection interface Advice shall be sought from the TfNSW Automatic Train Protection (ATP) project team on

guidelines for suitable interface arrangements where ATP balises are installed or where they are

proposed to be installed. The final arrangement shall be approved by the Lead Civil Engineer,

ASA.

Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Name Dorothy Koukari Joe Muscat John Paff Graham Bradshaw

Position Senior Engineer Standards (Civil)

A/Lead Civil Engineer A/Chief Engineer Rail Principal Manager Network Standards and Services


Page 1 of 42

Engi

neer

ing

Stan

dard

UNCONTROLLED WHEN PRINTED

UNDERBRIDGES

ESC 310

Engineering Standard Structures

Version 2.2

Issued July 2010

Owner: Chief Engineer Civil

Approved by: John Stapleton Authorised by: Richard Hitch A/Principal Engineer Chief Engineer Civil Technology & Standards

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

RailCorp Engineering Standard — Structures Underbridges ESC 310

© Rail Corporation Page 2 of 42

Document control

Issued July 2010 2.2 UNCONTROLLED WHEN PRINTED Version

Revision Date of Approval Summary of change

2.2 July, 2010 Changes detailed in Summary table below

2.1 November, 2009 Change of format and minor editing throughout; add configuration details for ‘continuous refuge’; minor rewording of requirements for ballast retention walls and intermediate rail supports on ballast walls

2.0 July, 2007 Additional minor requirements re existing structures, integrated designs, approved materials, services, nameplates, construction specifications, protection beams; Section on Standard Designs deleted; Minor changes to design loads for light lines; seismic loading; culverts; Transom top not to be used for new bridges; Criteria specified for bearings and deck joints; drainage and waterproofing; Additional criteria specified for direct fixation; Criteria specified for advertising signs; Collision protection risk table updated to be consistent with the RailCorp Safety Management System; Clarification of requirements for walkways and reference to standard drawings; Guard rail criteria updated: required for ballast top bridges over 20 metres in length; top of guard rail not more than 50mm below top of running rail; Reference to standard drawings for ballast retention wall, and for intermediate rail support; Clarification of earthing and bonding requirements.

1.1 May, 2006 Clarification of transom bolt size for retransoming of existing bridges

1.0 March, 2006 First issue as a RailCorp document. Replaces TS 30 000 3 01 SP, TS 31 200 1 01 SP, TS 31 400 1 01 SP, C 4005, C 4010, CTN 04/22

Summary of changes from previous version Section Summary of change

Document Control

Update version details

All Correction of internal section reference numbers

3.15 Change TMC 304 to SPC 301

11.3.10 Change TMC 304 to SPC 301

14.3.3 Add guard rail insulation requirements from CTN 08/06

16.3 Revision to transom bolt size for new bridges


© Rail Corporation Page 3 of 42 Issued July 2010 2.2 UNCONTROLLED WHEN PRINTED Version

Contents 1 Purpose, Scope and Application ............................................................................................................ 5 2 References ................................................................................................................................................ 5

2.1 Australian and International Standards ......................................................................................... 5 2.2 RailCorp Documents ..................................................................................................................... 5 2.3 Other References .......................................................................................................................... 6

3 General Requirements ............................................................................................................................. 6 3.1 Design Standards .......................................................................................................................... 6 3.2 Existing Structures......................................................................................................................... 6 3.3 Integrated Designs ........................................................................................................................ 6 3.4 Approved Materials........................................................................................................................ 7 3.5 Clearances..................................................................................................................................... 7 3.6 Earthworks..................................................................................................................................... 7 3.7 Provision for Services.................................................................................................................... 7 3.8 Safety............................................................................................................................................. 7 3.9 Protection of the Environment ....................................................................................................... 8 3.10 Heritage ......................................................................................................................................... 8 3.11 Protection of the Public.................................................................................................................. 8 3.12 Design Procedure – New or Infrequently Used Products.............................................................. 8 3.13 Nameplates and Plaques .............................................................................................................. 8 3.14 Drawing Standards ........................................................................................................................ 8 3.15 Construction................................................................................................................................... 8 3.16 Maintenance .................................................................................................................................. 9 3.17 Advertising Signs........................................................................................................................... 9

4 Design Loads............................................................................................................................................ 9 4.1 New Underbridges......................................................................................................................... 9 4.2 Refurbished Underbridges........................................................................................................... 10 4.3 Seismic Loading .......................................................................................................................... 10 4.4 Culverts........................................................................................................................................ 10

5 Bearings and Deck Joints ..................................................................................................................... 11 6 Track Structure Requirements.............................................................................................................. 11

6.1 General ........................................................................................................................................ 11 6.2 Ballast Top................................................................................................................................... 11 6.3 Transom Top ...............................................................................................................................11 6.4 Direct Fixation.............................................................................................................................. 12

7 Drainage and Waterproofing ................................................................................................................. 12 8 Culverts and Small Openings ............................................................................................................... 12 9 Waterway Requirements........................................................................................................................ 13

9.1 Hydrology and Hydraulic Requirements...................................................................................... 13 9.2 Requirements of Other Authorities and Government Departments ............................................ 13

10 Scour Protection .................................................................................................................................... 14 10.1 General Requirements ................................................................................................................ 14 10.2 Culverts........................................................................................................................................ 14 10.3 Underbridges ...............................................................................................................................14 10.4 Alternative Construction Materials............................................................................................... 14

11 Protection of Bridges over Roadways ................................................................................................. 15 11.1 Design Requirements .................................................................................................................. 15 11.2 Existing Bridges........................................................................................................................... 15 11.3 Protection Beams ........................................................................................................................ 15


© Rail Corporation Page 4 of 42 2.2 UNCONTROLLED WHEN PRINTED VersionIssued July 2010

12 Collision Protection ............................................................................................................................... 19 12.1 General ........................................................................................................................................ 19 12.2 Location of Piers, Columns and Deflection Walls........................................................................ 20 12.3 Design Loading............................................................................................................................ 20 12.4 Structural Configuration............................................................................................................... 21

13 Walkways, Refuges and Handrails ....................................................................................................... 21 13.1 Functional Purpose...................................................................................................................... 21 13.2 Walkways..................................................................................................................................... 22 13.3 Refuges ....................................................................................................................................... 23 13.4 Handrails...................................................................................................................................... 23 13.5 Configurations.............................................................................................................................. 23 13.6 Services ....................................................................................................................................... 24 13.7 Safety Marking and Signage ....................................................................................................... 24

14 Guard Rails ............................................................................................................................................. 24 14.1 Functional Purpose...................................................................................................................... 24 14.2 General Requirements ................................................................................................................ 24 14.3 Guard Rail Details ....................................................................................................................... 25 14.4 Joints in Guard Rails ................................................................................................................... 26

15 Bridge Ends ............................................................................................................................................ 27 15.1 General ........................................................................................................................................ 27 15.2 Functional Requirements............................................................................................................. 27 15.3 Approved Configurations ............................................................................................................. 27

16 Transoms ................................................................................................................................................ 28 16.1 General ........................................................................................................................................ 28 16.2 Design Requirements .................................................................................................................. 28 16.3 Fixing of Transoms ...................................................................................................................... 29

17 Electrical Requirements ........................................................................................................................ 29 17.1 Earthing and Bonding .................................................................................................................. 29 17.2 Clearances to Electrical Services and Equipment ...................................................................... 30 17.3 Provision for Attachment of Overhead Wiring ............................................................................. 30

Appendix 1 R Loading Configuration........................................................................................................ 31 Appendix 2 Typical Walkway, Refuge and Handrail Configurations ..................................................... 32 Appendix 3: Walkway Signage........................................................................................................................ 38 Appendix 4: Approved Bridge End Configurations ...................................................................................... 40

Engineered Backfill................................................................................................................................... 40 Ballast Retention Walls ............................................................................................................................ 41 Ballast Wall for Track Support.................................................................................................................. 42



1 Purpose, Scope and Application This document specifies the design requirements for underbridges on the RailCorp network.

This Standard does not cover the load rating of underbridges, which is documented in Standard ESC 301 “Load Rating of Underbridges”.

Underbridges are defined as bridges supporting the track and passing over waterways, roadways, railways, pathways and flood plains etc. They include culvert structures.

The term ‘culvert’ is used to refer to minor ballast-top openings comprising metal pipes, concrete pipes, concrete boxes, concrete arches, brick and masonry arches.

2 References

2.1 Australian and International Standards AS 1085.1-2002: “Railway Track Material Part 1: Steel Rails”

AS 1597.2-1996: “Precast reinforced concrete box culverts”

AS 1657-1992 “Fixed platforms, walkways, stairways and ladders – Design, construction and installation”

AS 1720.1–1997 “Timber structures – Design methods”

AS 1742.2 “Manual of uniform traffic control devices – Traffic control devices for general use”

AS 1743 “Road signs – Specifications”

AS 3600-2001 “Concrete structures”

AS 3818.1-2003 “Timber – Heavy structural products - visually graded, Part 1: General requirements” and Part 2 “Railway track timbers”

AS 4100-1998 “Steel structures”

AS 5100-2004 “Bridge design”

2.2 RailCorp Documents ESC 200 “Track System”

ESC 215 “Transit Space”

ESC 220 “Rail and Rail Joints”

ESC 230 “Sleepers and Track Support”

ESC 301 “Load Rating of Underbridges”

ESC 410 “Earthworks and Formation”

ESC 420 “Track Drainage”

SPC 301 “Structures Construction”

SPC 411 “Earthworks Materials”

EP 12 10 00 21 SP “Low Voltage Installations Earthing”

EP 12 20 00 01 SP “Bonding of Overhead Wiring Structures to Rail”



EP 12 30 00 01 SP “Electrolysis from Stray DC Current”

ESG 100.17 “Signal Design Principles Track Circuits”

Standard Drawing Numbers 785-568, 785-569, 785-570 and 785-571

CV 0041442 Standard Steel Walkway (With Refuge) to suit 9m to 15m Fabricated Steel Girder Spans

CV 0042333 Standard 1500 Wide Steel Walkway (Without Refuge) to suit 9m to 15m Fabricated Steel Girder Spans

CV 0048002 Extension for Standard Brick Arch Oviform Culverts

CV 0115011 Standard Ballast Retaining Wall

CV 0162590 Standard Intermediate Rail Support at Bridge Ballast Walls

RailCorp Safety Management System

SMS-12-PR-0371 “Managing Engineering Design Control”

2.3 Other References “Australian Rainfall and Runoff”, Institution of Engineers Australia 1987

“Waterway Design”, Austroads 1994

“Bridge Waterway Manual”, RTA September 2000

3 General Requirements

3.1 Design Standards All underbridges shall be designed to Australian Standard AS 5100 “Bridge design” and the requirements specified in this document.

3.2 Existing Structures When replacing or refurbishing an existing underbridge, the design shall comply with Section 3.1 and shall provide for the current and proposed future line usage and business requirements.

Refurbishment includes widening or extending existing bridges.

When replacing or refurbishing the superstructure only, the structural capacity of the substructure shall be assessed. The assessment shall be based on the actual loading from rail traffic. In determining the actual loading, any increased loading due to proposed future line usage and business requirements shall be included. The substructure shall be strengthened to meet the actual loading if the assessment determines the capacity is not adequate.

The extension of brick arch culverts shall be in accordance with RailCorp drawing CV 0048002 Extension for Standard Brick Arch Oviform Culverts.

3.3 Integrated Designs The design of each underbridge is to be integrated taking into account all associated requirements such as service routes, overhead wiring and signalling infrastructure, drainage, bonding and architectural treatments. Where appropriate, aesthetics are to be taken into account including proportions, details and finishes.



In locations that are vulnerable to vandalism and graffiti, appropriate measures are to be taken to discourage access to the bridge. Anti-graffiti paints should be specified in areas where there is a high risk of graffiti.

3.4 Approved Materials Approved construction materials for main structural elements are steel and concrete. With the exception of transoms, timber materials shall not be used as structural elements in the design of underbridges.

Masonry is approved for existing structures and as facing material for new structures where this is required in special circumstances such as for heritage reasons.

3.5 Clearances Where an underbridge passes over a road, pedestrian access, cattle access, navigable waterway or other rail line, horizontal and vertical clearances beneath the structure are to be provided in accordance with AS 5100 or RailCorp’s transit space standards, as applicable. For navigable waterways clearances are to be agreed with the relevant authority.

Clearances to bridge members above rail level (e.g. through girders or trusses) are also to conform with RailCorp’s transit space standards.

3.6 Earthworks Earthworks associated with underbridges are to be designed in accordance with RailCorp’s Standard ESC 410 “Earthworks and Formation”, Specification SPC 411 “Earthworks Materials” and the specification for engineered backfill in 15.3.1.

3.7 Provision for Services Provision may be required when designing underbridges for services owned by RailCorp (e.g. high voltage, low voltage, signalling, communications), or for services owned by other authorities and utilities (e.g. telephone, water supply, power and gas).

The designer shall consult with the relevant authorities and shall provide special ducts for both current services and future services where appropriate. Services shall be segregated where necessary, e.g. power and signalling.

The location and fixing of the service ducts is to be designed so that future access to the underbridge structure for inspection and maintenance is not impeded. The service ducts shall also be designed and located so that the future inspection and maintenance of the services is not impeded.

Service ducts shall be located to comply with RailCorp’s Engineering Standard ESC 215 “Transit Space”.

Where service ducts are attached to a bridge walkway, they must be positioned so that they do not encroach on the safe working area or create a trip or other safety hazard.

3.8 Safety The design of underbridges including the refurbishment of existing structures is to take into account safety considerations for construction and maintenance personnel, and any other parties including operations personnel who may be required to use the structure.

The requirements of the RailCorp Safety Management System, particularly SMS-12-PR-0371 Managing Engineering Design Control, are to be observed and incorporated in all designs.

Designs for underbridges and culverts shall provide safe access for inspection and maintenance. This may include access steps, ladders, cages, walkways and fixing points.


3.9 Protection of the Environment


The design of underbridges including the refurbishment of existing structures is to take into account environmental impacts during construction and maintenance activities, with a view to minimising any impacts.

3.10 Heritage Heritage considerations and classifications must be observed in all underbridge designs. This may have particular application in circumstances where an existing structure is being refurbished or modified, or where a new structure is being proposed in the vicinity of existing heritage items.

3.11 Protection of the Public Suitable protection is to be installed on bridges to prevent spillages from wagons conveying mineral products, ballast or spoil from falling through the bridge or off the side of the bridge onto road vehicles or pedestrians underneath. This may be achieved by the use of steel mesh or similar material, laid between transoms or fitted to the sides of safety walkways.

3.12 Design Procedure – New or Infrequently Used Products If any products specified in the design documentation can reasonably be deemed to be new or infrequently used, these must be identified by the designer and referred to the Chief Engineer Civil for approval. The designer must be satisfied that the manufacturer/constructor/maintainer understands any special requirements/practices relating to the product prior to release of the design documentation.

3.13 Nameplates and Plaques All new underbridges and underbridges that undergo major refurbishment are to be provided with nameplates, indicating the kilometrage and year of construction. The nameplates will normally be of brass construction and fitted to the outside of the bridge kerb at the Sydney end.

For ballast top bridges, plaques or stencilling are also to be installed in a visible location on the top of the kerbs, providing a warning that excess ballast and lifting of the track above the design level are not permitted over the bridge.

3.14 Drawing Standards Construction drawings are to comply with RailCorp’s standard procedures and formats, and are to detail the design criteria and any other information that is relevant to ensuring that the new structure is constructed and maintained in accordance with the design.

3.15 Construction Design documentation is to identify standards for construction, including construction methods, processes and materials.

RailCorp has a suite of technical specifications for construction of structures. The specifications are detailed in Engineering Specification SPC 301 “Structures Construction” and are to be incorporated in the design and construction documentation of underbridges.

Design documentation shall include relevant references for material testing and testing of welds.

The design of new underbridges and the refurbishment of existing structures is to take into account construction constraints, particularly under live operating conditions and track possession constraints.

Designers shall consider clearances from the track to the piling equipment when designing substructures. Clearances shall take account of transit space, safeworking and construction requirements to avoid both construction constraints and excessive length of abutments and piers. The minimum clearance is the kinematic envelope (out-of-gauge load) plus 200mm.



3.16 Maintenance The design of underbridges, including the refurbishment of existing structures, is to take into account the ability to access components for inspection and maintenance purposes. On steel underbridges, sufficient clearance shall be provided between end cross girders and ballast walls for this purpose.

Components, materials and finishes should be chosen to minimise future maintenance.

Maintenance requirements are to be specified in the design documentation for structures. Requirements are to include examination tasks and frequencies, damage limits, and repair standards. In most cases, ESC 100 “Civil Technical Maintenance Plan” and ESC 302 “Defect Limits” will apply. However site specific maintenance requirements may need to be provided.

3.17 Advertising Signs Design loadings for advertising signs shall be in accordance with relevant Australian Standards.

The underbridge shall be assessed for the structural capacity to withstand the advertising sign design loadings.

Fixing details shall be in accordance with design codes and practices. They shall not impact on the structural integrity of the bridge. They shall not create an obstruction that causes water to pond or debris to accumulate on the bridge structure. They shall only be made into existing structural members with the approval of the Chief Engineer Civil.

Fixings and ladders for the sign shall not impinge on the clear walking space of walkways and the clear space of refuges.

Signs and fixings shall not prevent access for inspection and maintenance of the bridge, including the structure immediately behind the sign.

4 Design Loads

4.1 New Underbridges New underbridges are to be designed to accommodate axle configurations in accordance with AS 5100 for the various Operating Classes as follows:

Main Lines

Passenger Main Line 200-LA plus DLA

Mixed Passenger Freight Main Line 300-LA plus DLA

Freight Line 300-LA plus DLA

Light Line 200-LA plus DLA

Heavy Freight Option 350-LA plus DLA

Sidings

General Yard 300-LA plus 50% DLA

Passenger operations/ or maintenance 180-LA plus 0% DLA

Table 1

NB. The ‘Reference Load’ is 300-LA. For the other loadings, all axles are to be proportioned by the ratio of the nominated LA load divided by 300.

Operating Classes are defined in RailCorp standard ESC 200 “Track System”.



For loadings less than 300 LA, future loading requirements need to be considered. Final approval of the design loads shall be obtained from the Chief Engineer Civil.

When designing through girders or truss bridges, secondary structural elements are to be incorporated in the structure to accommodate potential collision loading from a derailed vehicle, in accordance with AS 5100. These are required in order to protect the main structural elements of the bridge from damage.

Where underbridges are designed for installation beneath RailCorp infrastructure and will extend beyond the existing tracks, they are to be designed for the above loadings for the full extent of the rail corridor.

4.2 Refurbished Underbridges Design loads for major refurbishment of existing bridges including ballast top conversions and substructure renewals shall be as above, unless waivers have been approved by the Chief Engineer, Civil.

4.3 Seismic Loading The class of bridge for seismic loading in accordance with AS 5100.2 Table 14.3.1 Bridge Earthquake Design Category is:

− bridges on main lines are Type III i.e. essential to post-earthquake recovery.

− bridges on sidings are Type I, except for bridges over roadways or railways which are Type II.

4.4 Culverts 4.4.1 Loading

New culverts are to be designed to accommodate axle configurations as nominated for new underbridges above.

AS 5100 is to be used to determine the vertical live load pressure at the required depth below sleeper. Minimum and maximum ballast depths are to be considered as well as wheel configurations to determine the critical case.

AS 1597 is to be used to determine the horizontal component of live load (i.e. 0.5 times the vertical live load at the given depth). Loadings are to be determined at the top and bottom of the culvert leg and pressures distributed as a trapezoid.

The dynamic load allowance (DLA) is to be determined as follows:

− Box culverts: in accordance with AS 1597

− Suspended slab (deck slab supported as simply supported beam on legs): in accordance with AS 5100. Note that AS 5100 has no specific culvert option for determining Lα. If the span length is taken as Lα it gives a DLA of 100%, which is too conservative. Adopt other loads, load factors and load combinations from AS 5100. Where culverts are to be extended across the rail corridor to accommodate additional tracks or access roads, the following design loading is to be applied:

− Access road only: R20 (See Appendix 1 for details of R loading configuration)

− Rail loading: in accordance with Table 1.

4.4.2 Structural design Structural design is to be in accordance with AS 5100 except for shear design, which may be in accordance with AS 1597.

Fatigue design is to be in accordance with AS 5100.



5 Bearings and Deck Joints Bearings and deck joints shall be designed in accordance with AS 5100.4 “Bridge design, Part 4: Bearings and deck joints”.

The design loads shall be in accordance with AS 5100.2 “Bridge design, Part 2: Design loads”.

Bearings and joints shall be designed to provide sufficient access for the inspection, maintenance and replacement of the bearings and joints.

The minimum vertical distance between the underside of the main beams and the bearing shelf shall be 500mm.

Jacking points shall be provided on the bearing shelf.

6 Track Structure Requirements

6.1 General The track structure will normally be ballast top or direct fixation. Transom top bridges shall only be used where there are special factors that prevent the use of ballast top or direct fix.

Mechanical rail joints are not permitted on bridges. Anchoring of track and provision for expansion switches shall be in accordance with RailCorp Standard ESC 220 ”Rail and Rail Joints”, in particular Section 5.8.

The noise emitted from the underbridge should be the same level (within ±2 dBA) as that emitted from the track on the approach and departure from the bridge. This requirement applies to bridges in urban areas only. Ballast top structures are deemed to meet this requirement.

New bridge decks, except transom top, shall be structurally continuous without gaps or open joints to prevent matter and debris penetrating the deck within the spans. Where precast beams with gaps are used, there shall be a continuous deck slab rather than joints at the top surface.

Bridge decks installed during refurbishment/replacement of existing bridges shall wherever possible be structurally continuous.

6.2 Ballast Top Ballast top underbridges are preferred to transom top due to ease in maintaining the track and provide for a significant reduction in track degradation adjacent to bridge ends.

Specific component configuration requirements exist for guardrails, walkways, handrails and refuges and bridge ends, as detailed in this Design Standard.

The distance between the inside face of the ballast kerb and centre line of track is to be no less than 2150mm.

The height of the kerb is to be no less than 600mm. On superelevated track, a wider deck or higher kerb may be required to ensure that ballast is fully retained on the bridge. Ballast shall not spill onto underbridge walkways.

6.3 Transom Top Transom top bridges are generally not to be used for new or replacement bridges. If a transom top bridge is proposed for a particular situation, the prior approval of the Chief Engineer Civil is to be obtained.

Specific component configuration requirements exist for guardrails, walkways, handrails and refuges and bridge ends, as detailed in this Design Standard.



The design of transoms is to be in accordance with the details provided in Section 16 of this Standard.

6.4 Direct Fixation Direct fixation of the track to bridge decks may be considered where constraints such as limited vertical clearances exist below or above the track.

In situations where the deck is comprised of individual concrete girders with transverse stressing, the track is to be supported on monolithic girders to secure the track gauge.

Direct fixation bridges shall have concrete upstands to prevent a derailed train from falling over the side of the bridge. The upstands shall comply with the requirements of Section 14.1.

If concrete upstands cannot be provided, direct fixation bridges shall have guard rails in accordance with Section 14.3.

Track fastenings shall be approved fastenings for track slabs in accordance with ESC 230 “Sleepers and Track Support”.

The maximum height of grout bed under the rail fixings shall be 60mm. Where the hog of the girders results in a gap under the rail greater than 60mm high, packers may be used but they shall provide for full lateral restraint to the holding down bolt.

High impact epoxy grouts/mortars or specially developed grouts are to be used under the rails on direct fixation bridge decks to accommodate the high dynamic effects and movement of the deck. There shall be no metallic elements in the epoxy. Standard cementitious grouts shall not be used.

The grout bed shall provide sufficient edge distance to the bolt to avoid cracking of the grout.

The transition from ballasted track to the direct fixation bridge deck shall be designed to ensure a smooth transition. Some structural configurations are detailed in Section 15 of this Standard.

7 Drainage and Waterproofing New underbridges, except transom top bridges, shall have positive drainage systems to prevent water discharging from the bridge to the watercourse or road below. Decks are to be structurally continuous in accordance with Section 6.1.

For the refurbishment/replacement of existing underbridges, decks shall where possible have positive drainage systems. Where this is not possible, the waterproofing of the bridge deck is to be achieved by the use of membranes approved by the Chief Engineer Civil, and protected in turn from mechanical damage from the track ballast by the installation of shock mats or similar materials.

Drainage of bridge decks shall generally comply with the requirements of RailCorp engineering standard ESC 420 “Track Drainage”. The drainage system shall be cleanable. The minimum pipe size shall be 225mm diameter.

Drainage systems shall be designed to capture the water and drain it away from the track structure at the bridge end.

New ballast top bridges shall be provided with a waterproofing membrane to protect the deck concrete. The membrane shall be protected by a ballast mat.

8 Culverts and Small Openings Small span structures such as reinforced concrete pipes and precast culvert units etc. are basically “under formation” crossings. These products are generally commercially available and are designed in accordance with the requirements of AS 5100.



Buried metal structures (e.g. corrugated metal pipes) are generally not suitable for use in electrified areas and are not to be used for new structures on RailCorp’s network.

9 Waterway Requirements To design and size underbridge structures to satisfy waterway requirements, the following steps are required:

− Determine the hydrological and hydraulic requirements for the opening.

− Establish the requirements of other authorities and government departments.

The procedures to be followed are to conform with the requirements of AS 5100 and are generally to be in accordance with the RTA "Bridge Waterway Manual" September 2000, the “Austroads Waterway Design Manual” and “Australian Rainfall and Runoff”.

The determination of design flood and bridge waterway area shall be carried out by appropriately qualified and experienced engineers and shall be independently checked.

Where existing culverts require extension, the cross sectional area and the hydraulic performance of the extension shall be checked for the above criteria for new culverts. The hydraulic performance of the extension shall also be not less than that of the existing culvert.

9.1 Hydrology and Hydraulic Requirements Flood discharges are generally to be determined for average return intervals (ARI) of 10 year, 20 year, 50 year, 100 year, 2000 year and Probable Maximum Flood (PMF) events.

Bridge structures are to be designed for ultimate limit states (ULS) and serviceability limit states (SLS), in accordance with AS 5100.

Small culvert structures and minor openings may be designed for an ultimate limit state as follows:

− Discharge < 50 m3/sec: ARI of 50 years

− Discharge > 50 m3/sec: ARI of 100 years

Assessment of the hydrological and hydraulic requirements is to be typically carried out in three stages as follows:

− Field investigation: The study should include a sketch, the upstream watercourse shape, condition and slope, land use, records of previous floods, approximate kilometrage of catchment, details of other openings affecting the subject stream, evidence/extent of scouring/ponding/blockage, photographs and a field recommendation.

− Calculation for recommended waterway area: Relevant catchment characteristics should be determined using the procedures as set out in "Australian Rainfall and Runoff" together with extensive hydrological experience. The report should include the maximum discharges for the average return intervals listed above, the kilometrage of catchment divides, kilometrage, size and type of all openings within the catchment, and the distance from existing rail level to existing natural surface at the subject opening.

− Interpretation of calculations: The resulting flood height associated with various structural types and sizes is to be determined.

9.2 Requirements of Other Authorities and Government Departments Other authorities and government departments have a statutory role concerning streams and rivers. It is essential that they be contacted at an early stage in the development of the underbridge design to ensure that their requirements are addressed.

Preliminary plans shall be referred to the appropriate authority where the following circumstances apply:

− Tidal streams and rivers



− Non-tidal streams and rivers

− Navigable waterways

− Marine life

− Flood prone land and flood plains

10 Scour Protection

10.1 General Requirements Scour protection is to be designed generally in accordance with the RTA “Bridge Waterway Manual” September 2000 and Austroads “Waterway Design” 1994.

10.2 Culverts Scour protection will not normally be required when any one of the following criteria apply:

− The calculated velocity of flow through the culvert opening at design flow is less than 1.5 metres/per second.

− The bed and banks consist of sound rock or are protected by sound rock bars, and the toe of the embankment is protected.

− The gradient of the channel downstream is flatter than one percent.

− The calculated velocity of flow through the culvert opening at design flow is less than 2.5 metres/per second and the streambed consists of gravel or stones with 50 percent by weight exceeding 150mm.

Geometric considerations may require slope protection where scour protection of the bed is unnecessary.

If scour protection is required downstream of the culvert, it shall extend for a distance not less than 1.5 times the opening height from the end of the culvert. It shall also incorporate a cut-off extending 500mm below the bottom of the protection or to rock, whichever is the lesser, and shall be carried to the wing walls or up the sides of the channel to at least the serviceability limit states level. Negotiations will be required with adjoining landowners if this requirement results in the scour protection extending outside the railway boundary.

Scour protection shall be specially designed for channels with a grading steeper than one percent.

10.3 Underbridges Scour protection shall be provided to footings and pile caps where there is a potential for undermining resulting from scouring of the watercourse under the bridge.

The railway formation around the abutments and wings of a bridge is to be provided with appropriate scour protection where there is a history of scouring and washaways, or where hydrolgical and hydraulic assessments indicate a potential future problem. Similar protection of the railway embankment adjoining the bridge may also be necessary.

10.4 Alternative Construction Materials Alternative forms of scour protection approved for use around culverts and bridges include:

− Grassing of embankment faces

− Hand placed loose rock (rip rap)

− Sand bags filled with lean grout (e.g. 1 cement to 19 loam)

− Revetment mattresses (concrete filled)

− Gabion baskets or Reno mattresses (rock filled)

− Mortared spall



− Precast concrete headwalls

− Cast in situ concrete headwalls

− Cast in situ concrete aprons and cutoff walls

11 Protection of Bridges over Roadways

11.1 Design Requirements The design of new underbridges above roadways shall provide for clearances in accordance with the requirements of AS 5100. For bridges with concrete decks, a protection angle is to be cast into the leading edge of the outside member.

In exceptional circumstances, if for practical reasons it is not possible to achieve the specified clearances, clearances may be specified as approved by the road authority, subject to the approval of the Chief Engineer Civil. In these circumstances, collision protection is to be provided in accordance with AS 5100.

11.2 Existing Bridges 11.2.1 General

The risk of collision also applies to many existing underbridges over roadways, where the clearances are less than modern day requirements.

Clearances shall be determined by a survey of the road and soffit levels.

Where clearances cannot be provided in accordance with the current minimum standards:

− Low clearance signs and obstruction markers shall be provided in accordance with AS 1742.2 “Manual of uniform traffic control devices – Traffic control devices for general use” and AS 1743 “Road signs – Specifications”

− A risk assessment is to be undertaken in accordance with the RailCorp Safety Management System.

The risk assessment shall assess the vulnerability of the structure to impact from road traffic and determine whether impact protection is required. The aim of the assessment is to identify and prioritise underbridges for protection from motor vehicle collisions.

Vulnerable underbridges with a high risk of collision shall be provided with an appropriate form of protection against damage. The protection configuration shall be determined by the risk assessment. Approved protection configurations are:

− Protection beam

− Infrared detection system

− Warning frames.

11.2.2 Broad Flange Beams Underbridges with broad flange beams (BFB’s) have a history of brittle fracture from points of impact.

BFB underbridges that have received major hits from motor vehicles shall be replaced. Those with minor hits shall be protected or replaced. All other BFB underbridges over roadways without a history of collision should be included in the risk assessment as above.

11.3 Protection Beams 11.3.1 General

A protection beam is intended to either slow or stop a vehicle that is over-height for the measured clearance at a particular bridge site to prevent impact with the bridge superstructure.



A protection beam shall be constructed from suitable materials that are sufficiently strong to resist vehicle collisions without endangering the public and are durable in conditions of prolonged exposure.

The material shall be selected to form a beam that is sufficiently robust to remain integral, in place and effective after several severe strikes without requiring major repair. The chosen materials shall behave in a non-brittle manner upon impact and shall be readily repairable to restore structural strength for accumulated damage resulting from minor collisions.

Infill materials, where used, should not be considered to act compositely for strength purposes. However, infill material may be considered to serve such purposes as providing restraint to buckling of webs, the distribution of collision loading and the provision of a measure of internal corrosion protection, where necessary.

The protection beam soffit shall be smooth and without bolt head projections or the like.

The supports of such a beam must form an integral part of the main bridge structure. The protection beam shall not be attached to a free standing structure without the approval of the Chief Engineer Civil.

11.3.2 Design Loads The design loads shall be in accordance with AS 5100 except where specified in this Standard.

11.3.3 Soffit Level In order to protect a structure the soffit level of a protection beam (or gauge strip if provided) is to be set marginally lower than the measured clearance, sufficient to ensure that a colliding vehicle or its contents will impact on the protection beam rather than the bridge deck face.

For non-arched structures, the soffit level of a protection beam (or gauge strip if provided) shall be set 20mm below the soffit line of the structure it is to protect. The leading face side of a protection beam shall be positioned to ensure that it takes the initial strike. Adjustments in level, along the longitudinal axis of a protection beam shall also be made to allow for geometric conditions of road and rail (refer to Cases 1 and 2 in Figure 1).

For arched structures, the protection beam soffit level shall be set to form an imaginary chord line whose levels are set by the top side of an imaginary test rectangle (refer to Case 3 in Figure 1). The test rectangle shall be placed transversely in any position across a lane that permits high vehicles.


© Rail Corporation Page 17 of 42 2.2 UNCONTROLLED WHEN PRINTED Version

Figure 1

11.3.4 Vertical Deflection and Camber Where the calculated vertical structural deflection at the mid-span of a protection beam exceeds 6mm under serviceability conditions for self-weight and superimposed dead load, the calculated deflection shall be counteracted by an appropriate amount of pre-camber applied to the protection beam.

11.3.5 Horizontal Deflection and Placing of a protection beam The minimum horizontal clearance between a protection beam and the structure it is to protect shall be 100mm plus the calculated mid-span horizontal deflection of the protection beam under impact at the ultimate limit state. Access to allow room for maintenance of the protection beam and the protected structure shall be considered when deciding the actual clearance value. The protection beam must, however, be positioned so that it can reasonably be considered to be a part of the protected structure and should lie parallel to it rather than askew.

11.3.6 Gauge Strips Gauge Strips are sacrificial elements rigidly connected to the underside of the protection beam. The gauge strip is intended to be easily replaced, yet still providing the strength resistance of the protection beam.

Issued July 2010



11.3.7 Adaptability for Replacement and Damage Criteria The protection beam shall be designed to allow for ease of replacement following impact damage. Particular attention shall be given to the design of the supports to allow transmission of forces to the substructure without damage. Protection beams designed in sections may offer advantages in economy of erection, dismantling and reuse, particularly on sites with restricted access.

The designer shall, as far as is practicable, provide guidance for future maintenance or replacement purposes, and the extent and positions of possible local collision damage which can be accepted without requiring repair or replacement of the protection beam.

The condition of the existing sub-structure to which the protection beam support structure will be joined shall be surveyed and any weak areas strengthened. A system of dowelling or formation of shear keys to integrate the support and sub-structure shall be checked for adequacy to transfer all design loadings from the protection beam supported ends.

For the design of holding down bolts, anchorages, plinths, bases and structural aspects of foundations, the load factor shall be taken as 1.75 for the ultimate limit state and 1.30 for any serviceability limit state. The purpose of the enhanced load factors is to ensure that in the event of a severe collision the items described should be in an undamaged state, and only the beam section of the protection beam may need replacement. The design of such items shall include for the effects of any corrosion.

11.3.8 Protection for Road Users and Pedestrians The design of protection beams shall provide sufficient structural integrity so that on impact, the structure remains whole and collapse does not occur. Safety chains at each end of the protection beam must be installed which are capable of supporting its dynamic weight in the event of dislodgment from its supports.

11.3.9 Electrical Earthing and Use of Dissimilar Metals All metal components of a protection beam installation shall have electrical continuity in accordance with the Regulations of the Chief Engineer Electrical Systems. Where required, provision shall be made to allow for any electrical equipment required to be earth bonded and also any additional earthing connection necessary through the support structure by the provision of individual earthing rods.

Where dissimilar metals are to be used, the connections shall be designed in order to avoid the risk of galvanic corrosion. The electrical bonding of all metal components must be maintained.

11.3.10 Protection of Steelworks Against Corrosion Steelwork shall have protective coatings applied in accordance with SPC 301 “Structures Construction”.

Steelwork shall be either painted or galvanised.

The paint system shall be in accordance with TMC 304 Specification S24 “Protective Paint Coating of Steelwork – System P”.

Galvanising shall be in accordance with TMC 304 Specification S25 “Protective Galvanised Coating of Steelwork – System G”.

11.3.11 Brickwork, Blockwork and Stonework Where brickwork, blockwork or stonework is used to face any extended abutment walls, particular attention shall be given to:

− specifying a suitable mortar;

− layout of non-corrodable facing anchorages, ties and any reinforcement to mortar beds;

− vertical support to facings;



− the gap (30mm minimum) between the facing and the wall for effective sealing;

− provision of joints in brickwork to allow for relative thermal, structural and expansion effects.

11.3.12 Other Materials If structural materials other than those of steel or concrete are proposed, the agreement of the Chief Engineer Civil is required regarding the criteria for their design and use. The Chief Engineer Civil will need to be assured that such materials offer levels of safety, suitability and fitness for purpose, which are equivalent to those of steel or steel/ concrete.

11.3.13 Maintenance Access and Safety Appropriate provision for the maintenance and inspection of protection beam installations shall be agreed with the Chief Engineer Civil.

Where electrical or warning equipment is provided, other than lighting or signing, a fitted walkway of 600mm minimum clear width and of slip resistant finish shall be provided.

A safety handrail, in accordance with AS1657, shall be provided 1.10m above and around any horizontal surface to be walked upon during an inspection or maintenance works. The bottom 150mm of the handrail plane shall have a continuous solid upstand. The remainder of the handrail plane shall have 10mm maximum size safety mesh securely attached. Any access ladders shall comply with AS1657. All items of this clause shall be purpose fabricated.

11.3.14 Attachment of Signs and Equipment All signs and any other warning equipment supplied shall be securely attached to a protection beam structure using vibration resistant fixings. The structural design of a protection beam shall make adequate provision for the attachment of any equipment. Any subsequent modifications to structural members shall only be carried out with the approval of the Chief Engineer Civil.

11.3.15 Hazard Warning Markings Warning markings shall be painted on the full front face surface areas of a protection beam that are visible to the driver of an oncoming vehicle. The markings shall be stripes of 150mm minimum to 250mm maximum width and of 300mm minimum height. The stripes shall be of alternating yellow and black colour and sloping at 45 degrees to the vertical. The direction of slope, as viewed by oncoming traffic, shall be to the right for the protection beam face to the right of the road centre line and to the left for the remaining section of protection beam face.

11.3.16 Appearance The overall appearance is an important consideration for protection beams. Consideration shall be given to providing a structure with simple clean lines, which is in keeping with the structure it is intended to protect, and which shall require minimum maintenance. Reflective finishes which may dazzle in conditions of strong sunlight or reflected light from vehicle headlamps, shall be avoided. However, traffic sign faces and the yellow stripes of black and yellow markings need to be of reflective material to be effective at night.

12 Collision Protection

12.1 General The design of piers or columns supporting underbridges over rail tracks is to comply with the provisions for collision protection and loading in AS 5100.

For new structures, the preference is for a clear span between abutments.

The prime requirement is to protect the piers and columns against damage from a derailed train, which in turn could result in collapse of the structure onto the train.



Similarly, piers and columns located next to roadways should be protected against impact from road vehicles.

If an existing underbridge is being modified or extended and an existing pier or abutment is going to be converted to a common pier, provision is to be made for collision loading from any direction.

12.2 Location of Piers, Columns and Deflection Walls The minimum clearance to track centre line from any pier, column or deflection wall shall be as specified in ESC 215 “Transit Space”.

A pier or column shall not be located between tracks except on platforms. Variation to this may only be approved by the Chief Engineer Civil.

The preferred option when designing major refurbishment, replacement of a structure or construction of a new structure is to introduce structural redundancy in the superstructure to prevent collapse of the structure under impact loads.

12.3 Design Loading All piers or columns supporting an underbridge over rail tracks shall be designed in accordance with the provisions of AS 5100. The same requirements apply to major refurbishment works including any alterations to the piers or columns, increases in loads on the structure or expansion of the structure.

Clause 10.4.3 of AS 5100.2 need not apply to piers and columns located on platforms provided all of the following conditions are satisfied:

− Platforms are earth-filled and designed in accordance with relevant RailCorp standard. Note that earth-filled platforms will provide full dispensation in Section 10.4.3 of AS 5100.2. Suspended platforms will require to be assessed by rigorous analysis to demonstrate that the platform can provide an adequate level of protection to the pier or column when the platform is subject to design loading;

− Pier or column transverse location (with respect to track) is in accordance with RailCorp Engineering Standard ESC 215 “Transit Space” (e.g. in excess of 4.3m from centreline of track);

− Pier or column longitudinal location (with respect to track) is more than 20m from end of ramped platform, or is more than 2.6m from end of vertical (non-ramped) platform.

All piers and columns including those on platforms as described above, must satisfy Clause 10.4.4 of AS 5100.2 for the minimum design load. Platforms shall not be assumed to provide a degree of protection to permit reduction of the 500 kN collision load.

For temporary structures (less than 12 months) and refurbishment of existing structures, a risk assessment may be undertaken to determine whether any relaxation to the load requirements of AS 5100 can be made.

The risk assessment is to be performed in accordance with RailCorp’s Safety Management System. The analysis shall consider the following criteria:

− Site condition, cutting, embankment etc.

− Derailment history

− Type of structure, i.e. potential for collapse damage to trains

− Track geometry

− Track speed

− Type of rolling stock

− Future usage and growth in patronage.

The risk analysis shall also consider any other relevant site specific criteria.



The results of the risk analysis will determine the category of collision loading in AS 5100 that is to be applied to a support. The risk ranking determined from the risk analysis shall be equated to a loading requirement from AS 5100 as tabulated below:

RailCorp Level 2 Safety Risk Matrix

Ranking

AS 5100 Collision Loading Requirements

A All requirements of AS 5100.2 clause 10.4.3, clause 10.4.4, clause 10.4.5 and clause 10.4.6.

B AS 5100.2 clause 10.4.3 (using loading for between 10m and 20m from centre line of track), clause 10.4.4, clause 10.4.5 and clause 10.4.6.

C AS 5100.2 clause 10.4.4, clause 10.4.5 and clause 10.4.6.

D AS 5100.2 clause 10.4.4 and clause 10.4.6.

Table 2

The use of lower order protection devices such as earth mounds, gabions or guard rails etc. may be used in the risk analysis to reduce the risk ranking if approval is obtained from the Chief Engineer Civil.

12.4 Structural Configuration Piers or columns may be designed to withstand the load criteria stipulated in AS 5100 by configuring either as:

− individual units

− in combination with deflection walls, or

− solely reliant on deflection walls

Piers, columns and deflection walls shall comply with the structural configuration and geometric requirements of AS 5100.1. In addition, piers, deflection walls or the first column of a group shall have the leading faces rounded or vee-shaped.

In the case of retrofitting a deflection wall to an existing vulnerable pier or column, as well as infill walls, end walls shall extend parallel to the track, 3 metres on the approach side of the pier or column.

13 Walkways, Refuges and Handrails

13.1 Functional Purpose Walkways serve the following purposes:

− protect authorised personnel from falling when crossing a bridge;

− provide a safe pathway for train crew in the event of a train having stopped or failed on a bridge;

− facilitate track inspection;

− facilitate the replacement of transoms, sleepers and other track components.

Refuges serve the following purpose:

− provide a safe area on a bridge for authorised personnel to stand clear of a passing train. Note: Standard width walkways do not provide a safe area or refuge.



Handrails serve the following purpose:

− protect authorised personnel and train crew from falling off the side of the bridge and approaches.

13.2 Walkways 13.2.1 General

Walkways shall be installed on underbridges where the height from bridge deck to the lowest invert level is greater than 2 metres.

When designing the location of walkways, consideration is to be given to particular site characteristics such as flood issues (e.g. afflux and debris), track curvature, sighting distances and train lengths.

On single tracks where walkways are required, they should be installed in the following order of preference:

− downstream side of a bridge over water where flood levels are high;

− on the ‘outside’ of a bridge on a curve;

− on the same side of the track on adjacent bridges spaced less than one train length apart, with the ‘worst’ safety access bridge governing the side selected for the walkway.

One walkway is to be provided on single track bridges and on double track bridges less than 15m long. Two or more walkways are required on double track bridges longer than 15m and on multiple track bridges. Refer to the typical configurations for walkways, refuges and handrails as shown in Appendix 2.

Where provided, walkways are to be extended with suitable detailing at each end of the bridge to provide a safe transition to the approaches and adjoining rail embankments. Particular attention is to be given to the detail where the last walkway panel abuts the face of the abutment, to ensure that adequate support is provided to the walking surface.

13.2.2 Design Criteria The following design criteria shall apply to walkways on underbridges:

− normal loading is to be self-weight plus 5kPa live load, i.e. when no special storage bays are provided;

− on major bridges where special storage bays, designated by signage, may be provided, general walkway loading may be reduced to 3kPa live load. The reduced walkway loading is also to be designated by signage;

− on transom top bridges, there should generally be no gap between the end of the transoms and the walkway deck;

− where a grating is required in the 4-foot or on the transom ends, a proprietary material is to be used that will not lift or deform. Products such as expanded metal are not to be used where they are prone to deformation and lifting at the ends, thereby creating a trip hazard or the risk of being picked up by a passing train;

− on excessively wide ballast top deck bridges, i.e. 3 metres and greater from centreline of track to edge of bridge, no discrete walkway will be required. In this case a handrail will be provided , irrespective of deck to invert height;

− for through truss/girder bridges, structural elements are permitted to locally infringe clearance requirements when fitting internal walkways subject to a waiver being obtained from Chief Engineer Track. This is preferred to the provision of external walkways, from which a track patroller could not effectively inspect the track;

− minimum clear walking space of 600mm.

− for transom top bridges, the surface of the walkway is to be at or below underside of transom level and not greater than 300mm below top of transom level;



− on ballast top bridges, the normal standard is to set the walking surface of the walkway level with the top of the kerb;

− walkway components are to comply with Australian Standards AS 3600, AS 4100 and AS 1657.

13.2.3 Walkway Storage No walkway shall be loaded beyond the design value. If storage requirements exceed this value, storage bays are to be provided and designated by signage. 5kPa live load equates to 300 kg loading per metre length of 600mm wide walkway.

13.3 Refuges Refuges shall be provided on underbridges over 20 metres in length.

Refuges may be required on bridges less than 20 metres where site conditions warrant their installation.

The distance between refuges is not to exceed 20 metres over the length of the bridge. The spacing at each location is to be determined by a risk assessment, taking account of factors such as train speed, available sighting distances, the existence of warning light systems.

Refuges shall have a minimum clear space of 700mm depth and 1500mm width.

To establish the need for refuges and/or signage, the default clearances from the centreline of the nearest track to the front of a refuge are:

− 2230mm on straight track

− 2500mm on curved track

Where circumstances prevent the installation of refuges and the clearance from the track centreline to the back of a walkway is less than the kinematic envelope (out-of-gauge load) plus 600mm, warning signs are to be installed as detailed in 13.7.3 below.

Walkways may be used to provide a ‘continuous refuge’ where the particular circumstances (e.g. sighting distances, traffic volumes, bridge length) warrant such provision.

Where a walkway is to provide a ‘continuous refuge’, configuration details shall be:

− yellow safety line at kinematic envelope plus 200mm from track centreline

− clear walking space of 600mm behind the yellow line for the length of the walkway.

13.4 Handrails Handrails are to be provided on the outside of walkways and refuges and also on the opposite side of a ballast top underbridge where the height from deck to invert exceeds 2 metres.

Handrails are to consist of vertical posts together with a top rail and intermediate rail. Specific layouts are to be in accordance with the proprietary specifications of approved suppliers. The height of the top rail is to be not less than 950mm above the deck surface.

13.5 Configurations Typical configurations for walkways, refuges and handrails are shown in Appendix 2.

In most situations, walkways will be cantilevered on the outside of both transom top and ballast top structures. In addition, a walking area by way of a grating may also be required on transom top bridges in the 4-foot and on the transom ends.

Walkways shall generally comply with the layout, fixing and componentry detailed on the following drawings:



CV 0041442 Standard Steel Walkway (With Refuge) to suit 9m to 15m Fabricated Steel Girder Spans

CV 0042333 Standard 1500 Wide Steel Walkway (Without Refuge) to suit 9m to 15m Fabricated Steel Girder Spans

13.6 Services Services and utilities for RailCorp and external parties shall be located so as not to infringe on the walking or standing areas.

They are to be located to the outside of the walkway and extra width of walkway shall be provided to achieve the minimum walking space specified above.

13.7 Safety Marking and Signage 13.7.1 Safety Marking

Delineation of the safe areas to walk and stand on a walkway/ refuge is to be provided by a line 75mm wide and painted in Safety Yellow colour.

13.7.2 Restrictions on Use Each walkway shall display a sign at each access end showing ‘Authorised Persons Only’. An ‘Authorised person’ is a person authorised by RailCorp or its agents to enter onto and cross rail bridges.

The sign is also to incorporate a warning regarding the restriction on loading.

Details of a typical sign are provided in Appendix 3.

13.7.3 Limited Clearances An additional sign is to be attached to all underbridges with walkways where the clearance from track centreline to the walkway handrail is less than the kinematic envelope plus 600mm. The specification for this sign is provided in Appendix 3. Where similar signs have previously been provided, they should be replaced with the new sign when due for replacement.

14 Guard Rails

14.1 Functional Purpose The prime purpose of guard rails on underbridges is to keep derailed or derailing bogies/wheels tracked parallel to and in close proximity to the running rails. This action prevents a derailed train from falling over the side of the bridge.

In the case of through girder and through truss type underbridges, the guard rails prevent impact with key structural supporting elements.

For through girder, through truss and direct fix bridges concrete upstands may be provided in lieu of guard rails. The upstands shall be designed for a 80kN lateral load. The design shall take account of cross drainage requirements. The upstand shall comply with the relevant configuration requirements for guard rails.

In addition, the guard rails, by way of a baulking effect, provide additional support to the track at the bridge ends.

14.2 General Requirements Guard rails shall be installed on the following underbridges:



− Through span bridges and their approach spans;

− Transom top bridges;

− Ballast top and direct fix bridges over twenty metres in length.

For other ballast top bridges, a risk assessment should be undertaken in accordance with RailCorp’s Safety Management System, to determine whether guard rails are required. The following criteria are to be taken into account:

− Height of bridge;

− Bridge span;

− Bridge configuration e.g through girder, through truss where vulnerable to train impact loads;

− Abutment configuration;

− Probability and consequence of a derailment;

− Track alignment and configuration;

− Train speed, density and type of traffic.

14.3 Guard Rail Details 14.3.1 Configuration

Guard rail installations are to comply with the following requirements:

− Guard rail shall be new rail manufactured to AS 1085.1 or recycled rail Category 1 (White rail) in accordance with ESC 220 “Rail and Rail Joints”.

− Guard rail section is to be the same as the running rail or one section size less than the running rail.

− Top of guard rail is to be no higher than the adjacent running rail and no more than 50mm below the running rail.

− Each guard rail is to be plated and fastened on both sides to every transom/sleeper.

− Tapered nose section (“vee”) is to extend for a minimum of 3.6 metres beyond the abutment on the train approach side of the bridge. The design of the vee shall be in accordance with Drawing Number 785-570. The nose of the vee shall be bolted.

− Rails are to extend parallel for a minimum of 3 metres beyond the abutment on the train departure side of the bridge.

− Where traffic is bi-directional, the tapered guard rail section is to be installed at both ends of the bridge.

− Clearance between gauge face of running rail and adjacent face of guard rail is to be 380mm.

− Block-out holes for guard rail fastenings in concrete sleepers shall be grouted with an approved high strength grout.

For fixing details, dimensional set-out and componentry detail and sizes, standard guard rail drawings are available:

785-568 Bridge guard rails Ballast top bridge Arrangement for concrete sleepered track

785-569 Bridge guard rails Details of concrete guard rail sleepers Concrete sleepered track

785-570 Bridge guard rails Ballast / Transom top bridge Arrangement for timber sleepered track

785-571 Bridge guard rails Timber sleepered track Details of special plating for tapered nose


© Rail Corporation Page 26 of 42

14.3.2 Special Installations Where expansion joints exist, specific design details of guard rail installations will be required. Approved track fixings are to be used. The design is to be certified by a competent design engineer.

Where noise and vibration limiting track fixings are used and there is a mismatch in height between the bridge ties and the end treatment ties, the guard rail and vee shall be supported on all ties with approved products such as rubber pads and fastened to all ties with approved track fixings.

14.3.3 Signalling Interface Suitable isolation arrangements are to be made, where required, in track circuited and electrified areas.

The tapered nose section (“Vee”) is to be insulated with an approved component - refer to Figure 2. Generally one insulated joint is satisfactory. This insulation requirement applies to new installations and where refurbishment of the guard rails is undertaken.

Figure 2

Where guard rails exceed 50 metres in length, additional insulation and bonding arrangements may be required. Design drawings are to specify that insulation and bonding arrangements shall be in accordance with the requirements of the Chief Engineer Signals. See RailCorp Engineering Standard ESG 100.17 - Signal Design Principles Track Circuits.

14.4 Joints in Guard Rails Whilst no joint is permitted in running rails on bridges, guard rails may have minimal joints with at least two bolts on each side.

If standard fishplates are used, six bolts are required.

Issued July 2010 2.2 UNCONTROLLED WHEN PRINTED Version



If modified fishplates are used, the four bolts shall all have the nuts on the inside. Fishplates shall be modified by machining, not by oxy-acetylene cutting.

No joints are permitted in the vee.

15 Bridge Ends

15.1 General The design of new underbridges and the major refurbishment of existing underbridges shall provide for the stability and compaction of the bridge ends.

This applies to ballast top, direct fix and transom top bridges.

15.2 Functional Requirements Bridge ends shall be designed to:

− provide a transition between solid and flexible track support systems;

− maintain the integrity of the ballast profile at the end of the bridge;

− maintain the integrity of the ballast condition;

− maintain the tie support across the interface.

15.3 Approved Configurations RailCorp has approved a number of structural configurations for improving the perfomance of bridge ends. Selection of the most appropriate configuration for each location will be influenced by the following factors:

− traffic density, tonnage and speed;

− feasibility of implementation;

− whether the improvement is part of a construction, upgrading or maintenance activity.

Typical details and drawings of approved configurations are provided in Appendix 4. These configurations include:

− engineered backfill

− reslilient pads and vibration isolation rail fasteners

− approach slabs

− ballast retention walls

− intermediate rail support on ballast walls.

15.3.1 Engineered Backfill The formation immediately behind the abutments can be constructed in layers of selected compacted fill reinforced with geogrid. Provision shall be made for drainage below the compacted fill.

A typical layout of engineered backfill is shown in Appendix 4.

15.3.2 Resilient Pads and Vibration Isolation Rail Fasteners On transom top and direct fixation structures, resilient pads or vibration isolation rail fasteners may be installed on concrete sleepers on the bridge approaches and on the bridge.

Reference should be made to RailCorp’s standard drawings and layouts for the use of these components.



Timber transoms may be installed instead of sleepers on the bridge approaches to increase the stability of the bridge ends.

The use of concrete sleepers just at bridge ends in timber sleepered areas is not recommended, unless vibration isolation rail fasteners are fitted to the concrete sleepers and transoms.

15.3.3 Approach Slabs A transitional stiffness can be provided between the bridge approaches and the bridge deck itself by the installation of concrete approach slabs.

Where bridges are located on a skew, the end of the approach slab shall be shaped to be perpendicular to the track, to avoid rocking of the sleepers.

Approach slabs may be used in conjunction with track slab and ballast top, transom top and direct fixation bridges. When installed on a ballast top bridge, they should be provided with kerbs lining up with the kerbs on the deck of the bridge.

15.3.4 Ballast Retention Walls Ballast retention walls may need to be installed at bridge ends to prevent loss of ballast from the track. Retaining the ballast profile will reduce the rate of deterioration in the track top and also assist the track’s lateral stability.

Ballast retaining walls may be constructed from posts and guardrailing or precast concrete walls. Concrete walls are preferred - refer to RailCorp’s standard drawing CV 0115011 Standard Ballast Retaining Wall. Typical layout details for post and guardrailing are shown in Appendix 4.

15.3.5 Intermediate Rail Support on Ballast Walls The maximum spacing between the centre of the last sleeper and the centre of the first transom on a bridge should be limited to 600mm.

In situations where centres in excess of 600mm cannot be avoided, a specially designed support must be installed at the ballast wall, enabling the tie spacing to be restored to normal and reducing the forces at the bridge end.

This configuration includes the use of a resilient rubber pad on top of the ballast wall, which provides support to the rail when deflecting under load. A typical layout is shown in Appendix 4. Reference shall be made to RailCorp’s standard drawing CV 0162590 Standard Intermediate Rail Support at Bridge Ballast Walls for detailed requirements.

16 Transoms

16.1 General Transoms are primary load carrying elements of a railway underbridge. They have been traditionally cut from hardwood timber, although alternative materials (e.g. laminated timber or other composite materials) may be developed in the future.

Timber transoms are to conform to the requirements of AS 3818.1-2003 “Timber – Heavy structural products - visually graded, Part 1: General requirements” and AS 3818.2-2003 “Timber – Heavy structural products – visually graded, Part 2: Railway track timbers” and AS 1720.1 – 1997 “Timber structures – Design methods”.

16.2 Design Requirements Timber transoms are to be 250mm wide and have a minimum length of 2800mm. The spacing should not exceed 600mm.

Table 3 below gives the minimum thickness of transoms (measured at any point along the length of the transom), based on:



− Design loading of 300LA + DLA

− Track speed of 115 km/h

− Timber stress grade of F22 (Strength Group 2) in accordance with AS 3818.2

− Timber joint strength of J1

− Holding down bolt size M30

Girder centres spacing

(mm)

Transom spacing (mm)

Horizontal alignment of track

(Radius m)

Minimum transom thickness

(mm)

> 800 170 500 - 550

< 800 200

> 800 190

2000

600

< 800 210

> 800 190 500 - 550

< 800 220

> 800 200

2100

600

< 800 220

Table 3

Adjustments to the above minimum thicknesses are to be made if different stress grades and joint strengths of timber are used.

Special approval may be given by the Chief Engineer Civil for thinner transoms to be used where restricted clearances exist (such as electrified track on a through truss underbridge). This approval may impose additional inspection and maintenance requirements.

Track offsets from span centreline > 70mm are not permitted without approval of the Chief Engineer Civil.

16.3 Fixing of Transoms Approved fastenings for fixing transoms include swage bolts and galvanised bolts with conical springs and nylon lock nuts.

For new bridges, bolts should be a minimum size of M24 and grade 8.8. The preferred bolt size is M30 where the axle load is 30 tonnes and either the track is curved or axle spacing is less than 1300mm.

For retransomming of existing bridges, bolt size shall be determined by compliance with edge distance requirements. Bolts should be a minimum size of M22 and grade 8.8.

Bolts are to be manufactured to meet the requirements of Australian Standard AS/NZS 1111.

Square cut notching of timber transoms is not permitted.

17 Electrical Requirements

17.1 Earthing and Bonding Designs shall provide for earthing and bonding of metallic components on the bridge to mitigate touch potential hazards and corrosion of steel.



The design strategy should be to “design out” earthing and bonding issues by separation and isolation of metallic structures. Where this is not possible, the design shall achieve an appropriate balance of the risks associated with touch potentials and corrosion due to stray currents.

Design requirements are:

− Steel and concrete bridges shall be insulated from earth.

− Overhead wiring structures on bridges shall be bonded via a spark gap.

− Overhead wiring fittings attached to a bridge shall have tertiary insulation and be bonded via a spark gap.

− Vertical safety screens shall be insulated from the bridge structure.

− Horizontal safety screens shall be insulated from the bridge structure and shall be bonded via a spark gap.

− Other metallic components such as walkways, refuges and handrails shall be insulated from the bridge structure.

− Utility services, such as water, gas, communications and lights, shall be insulated from the bridge structure. There shall be a 2 metre separation between light columns and any other metallic structure.

Insulation panels may be required in fences and vertical safety screens to prevent transfer of potential.

Electrical requirements are specified in RailCorp Electrical Engineering Standards for Earthing, Bonding and Electrolysis, in particular:

− EP 08 00 00 07 SP “Safety Screens for Bridges over 1500V OHW Equipment”

− EP 12 10 00 21 SP “Low Voltage Installations Earthing”

− EP 12 20 00 01 SP “Bonding of Overhead Wiring Structures to Rail” and

− EP 12 30 00 01 SP “Electrolysis from Stray DC Current”.

17.2 Clearances to Electrical Services and Equipment Electrical services within the rail corridor may include aerial lines, 1500V dc overhead traction wiring and equipment and exposed low voltage equipment.

Bridges are to be designed and constructed to ensure that minimum clearances are observed to all electrical power lines and equipment, as laid down within the Australian Standards, the regulations of the relevant electrical authorities and RailCorp’s Electrical Standards.

Where high voltage aerial lines are located above the bridge, measures shall be taken to ensure that the risk of transferred potential associated with fallen conductors is mitigated.

The deck structure in the vicinity of overhead wiring beneath the bridge shall be designed to provide an impenetrable barrier intended to prevent persons from contacting 1500V dc equipment.

17.3 Provision for Attachment of Overhead Wiring The bridge structure shall be configured so that overhead wiring support and registration equipment can be attached where necessary (requirement depends on the width of the bridge).



Appendix 1 R Loading Configuration

R Loading Configuration

The ‘R’ vehicle is a rigid truck with the same configuration as the prime mover portion (first 3 axles) of the ‘T’ vehicle and the numerical portion is the vehicle’s weight in tonnes.

Issued July 2010

. Standard

T44 Vehicle

4.9 9.8 9.8 9.8 9.8 Axle Loads(Tonnes)

3700 1200 Variable 3000-8000 To produce maximum loading effect

1200

1800

Design Vehicle Configurations

R20 Vehicle

4.0 8.0 8.0 Axle Loads (Tonnes)


© Rail Corporation Page 32 of 42 Issued July 2010 UNCONTROLLED WHEN PRINTED Version 2.2

Appendix 2 Typical Walkway, Refuge and Handrail Configurations

SINGLE TRACK – TRANSOM TOP

Less than 15m length

All Cases

Walkway

DOUBLE TRACK – TRANSOM TOP

Walkway

50mm clearance

300mm maximum



DOUBLE TRACK – TRANSOM TOP

Walkway

Refuges Mesh placed adjacent to refuge for access from walkway

Refuges

Greater than 15m length - use where sighting is restricted

Greater than 15m length - use on straight track only

Walkway Walkway



DOUBLE TRACK – BALLAST TOP

SINGLE TRACK – BALLAST TOP


All Cases

Handrail

Walkway

Handrail Handrail



QUADRUPLE TRACK – TRANSOM TOP


Walkway

Greater than 15m length

Walkway Walkway

Walkway Walkway Walkway Walkway Walkway

Mesh Mesh Mesh Mesh

Alternate design for locations where adjacent transoms are not at same level

RailCorp EngineerinUnderbridges

g Standar d — Structures ESC 310

Page 36 of 42

© Rail Corporation Issued July 2010 UNCONTROLLED WHEN PRINTED Version 2.2

DOUBLE TRACK – BALLAST TOP


QUADRUPLE TRACK – BALLAST TOP


Walkway

Walkway

Walkway

Walkway



Kinematic + 200

700Service ducts located outside refuge clear space

Handrail shaped to suit

Refuge

REFUGE CONFIGURATION

Walkway

Refuge

Kinematic + 200

700

Min 600

75mm widecontinuous line insafety yellow

REFUGE/ WALKWAY COMBINATION

Issued July 2010



Appendix 3: Walkway Signage 300

ACCESS FOR AUTHORISED 20

PERSONS ONLY 250 WALKWAY NOT TO BE USED FOR

STORAGE OF MATERIALS. MAXIMUM LOADING 500KG PER SQUARE METRE

15

RAILCORP

RESTRICTED USE SIGN

220

187

20 20

20

10

20

15

20 66 44

LIMITED CLEARANCE SIGN

Specification for the limited clearance sign is:

− Sign size 220mm x 187mm

− Letter size 20mm

− Black text on white retro reflective background

− Sign to be made from the following high strength, corrosion resistant aluminium grades:

∼ Extrusions: AS 2848.1 Grade 6063 T6 or 6061 T6

∼ Sheet: AS 2848.1 Grade 5251 H38

− Sign sheet metal to be 2mm thick

− Retro reflective material to AS 1906.1

Issued July 2010



− Sign attached to handrail with lettering facing along track (must be placed so that staff approaching the bridge become aware of Danger)

− Attach to handrail so that inner edge of sign does not project into the walkway space beyond the inner edge of the handrail



Appendix 4: Approved Bridge End Configurations Engineered Backfill

NEW FORMATION LEVEL (TOP OF CAPPING LAYER - SEE DRG No. SP521

GRADED BACKFILL

Class "GMB20" back fill to RTA MR Form 744 compacted as for embankment fill or equiv. To be placed over the full width of embankment.

EMBANKMENT FILL Suitable fill (see ConstructionStandard) to be placed in 150mmlayers and compacted at optimummoisture content to 95% of the drydensity as measured by themodified compaction test inaccordance with AS1289 E2-1-1977.

Geotextile, Bidum U34 or equiv.

Geotextile, Bidum U34 or equiv. only to be used if existing embankment has 10% or more of material passing a 5mm sieve, or if any silty or clay materials are present.

Geotextile, Bidum U34 or equiv.

"Tensar Geogrid SS2" to be placed as 2/4m sheets overlapped 300mm on centre line of track

Agricultural draindown at 1:30 from cenof track to ea

to gradetre line

ch side ofembankment.

Granular fill around agricultural drain

30 degrees

1000

300 typ

Issued July 2010



Ballast Retention Walls

BAL.LOG

ABUTMENT

FLEXBEAMGUARDRAIL

A-

FOOTINGMASS CONCRETE

WINGWALL

1000

1000

1000

2000

PLAN

BRIDGE DECK

N.T.S.

BALLAST

600

900

STANDARD FLEXBEAM POST1800 LONGDRILL ON SITE TO SUIT

600 MIN.

VARIES TO SUITSITE CONDITIONS

FLEXBEAMGUARDRAIL

900(TYP)

600

25 MPaCONCRETEFOOTING

SECTIONN.T.S.

A-

FORMATION LEVEL

NOTE:BALLAST CAN BE EXCAVATED AND SUPPORTEDWITH STAR PICKETS AND TWO LAYERS 20mmPLYWOOD WHILE CONSTRUCTION OF FLEXBEAMGUARD RAIL TAKES PLACEFLEXBEAM MUST NOT ENCROACH ON STRUCTUREGAUGE.

Issued July 2010



Ballast Wall for Track Support

TRANSOM

BRIDGE GIRDER

BALLAST WALL

TIMBER BALLAST

SLEEPERRAIL

A-

12.7mm FABREEKA SA47 RAIL PAD,EPOXY ADHESIVE TO RAIL/SHIMS

MILD STEEL SHIMS SPIKED TO LOG

LOG

SECTION1:5

A-