Technical Note - TN 059: 2015 - Transport for NSW · Excavation work shall not commence without a risk assessment and implementation of appropriate controls. Refer to TMC 411 Earthworks

Technical Note - TN 059: 2015

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


Subject: Withdrawal of ESC 410 Earthworks and Formation

Issued date: 06 October 2015

Effective date: 06 October 2015

For queries regarding this document [email protected]

www.asa.transport.nsw.gov.au

This technical note is issued by the Asset Standards Authority as a notification to remove from

use the RailCorp standard ESC 410 Earthworks and Formation, Version 2.0.

ESC 410 is a legacy document and shall be used for reference purposes only. ASA standard

T HR CI 12110 ST Earthworks and Formation, Version 1.0 supersedes this document.

Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Date

Name Sarath Fernando Richard Hitch John Paff Graham Bradshaw

Position Principal Engineer Geotech

Lead Civil Engineer A/Chief Engineer Rail Director Network Standards and Services

mailto:[email protected]


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

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Subject: Update to RailCorp engineering standards ESC 410, ESC 540 and TMC 411

Issued date: 11 June 2015

Effective date: 11 June 2015

For queries regarding this document [email protected]

www.asa.transport.nsw.gov.au

This technical note supersedes TN 009: 2013 and is issued by the Asset Standards Authority as

a temporary update to the standards listed in Table 1.

Table 1 – RailCorp engineering standards

Reference No Title Version Issue date

ESC 410 Earthworks and Formation 2.0 01/07/2010

ESC 540 Service Installations within the Rail Corridor 2.2 01/07/2010

TMC 411 Earthworks 2.0 01/07/2010

The SMS document reference on CTN 13/04 has changed to SMS-06-GD-3066 Guide to

managing construction hazards.

Documents listed in Table 1 are presented as legacy RailCorp documents and shall be read in

conjunction with this technical note and interpreted according to the interpretation guides listed in

Table 2.

Table 2 – Interpretation guides

Reference no Title Version Issue date

TS 10762 Legacy RailCorp Standards Interpretation - Management Overview

1.0 28/06/2013

TS 10760 Guide to interpretation of organisational role and process references in RailCorp standards

1.0 17/06/2013

TS 10760 - SMS Interpretation guide RailCorp SMS References within RailCorp engineering standards

1.0 17/06/2013



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

http://www.asa.transport.nsw.gov.au/sites/default/files/asa/asa-standards/ts-10762.pdf




http://www.asa.transport.nsw.gov.au/sites/default/files/asa/asa-standards/ts-10760-sms.pdf

http://www.asa.transport.nsw.gov.au/sites/default/files/asa/asa-standards/ts-10760-sms.pdf

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1. Embankment/cut slope instability due to toe disturbances and trenching This instruction includes mandatory requirements.

There have been several embankment destabilisations reported as a result of excavations into

the toe of embankments. As shown in the photographs (Figure 1 to Figure 5), it appears that the

toe was cut to create access at the expense of embankment stability.

Removing the toe restraint, which is an integral part of the earth structure, leads to slip failure

progressing towards the track. This is one of the worst forms of destabilisation for dynamic

loading. It was noted that vertical cuts were left unsupported until track patrol discovered the slip

failure.

Each incident led to emergency repairs being undertaken to reinstate the embankment with

temporary speed restrictions to manage the risk until repairs had been completed.

Embankment toes and slopes shall not be disturbed by any means including cuts, cable and pipe

trenches or otherwise as this directly affects the stability of the earth structure.

If excavation is unavoidable, advice shall be sought from the geotechnical engineer.

Any trenching at the toe of cuttings for cable routes, cess drainage and so on, shall not be carried

out without a stability assessment or advice from the geotechnical engineer. Trenches especially

at top of soil/soft rock cuttings and embankments shall not be left open overnight. Water ponding

in trenches can result in slope failures (see Figure 4 and Figure 5).

Excavation work shall not commence without a risk assessment and implementation of

appropriate controls.

Refer to TMC 411 Earthworks and SMS-06-GD-3066 Guide to managing construction hazards for

requirements for excavation work including planning of works, risk assessment, excavation work

plans and excavation procedures. Also, refer to ESC 540 Service Installations within the Rail

Corridor for detailed requirements for the location and installation of cables and pipes by

trenching.


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Figure 1 - Vertical toe cut leading to slip failure

Figure 2 - Vertical toe cut leading to slip failure

Figure 3 - Vertical toe cut with high risk for slip failure


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Figure 4 - Cable trench left open at top of soil/soft rock cutting allowed ponding water to enter slope leading to failure (see Figure 5)

Figure 5 - Failure due to cable trench left open at top of soil/soft rock cutting

Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Name Sarath Fernando Richard Hitch John Paff Graham Bradshaw

Position Principal Engineer Geotech

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


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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

Page 1 of 16 UNCONTROLLED WHEN PRINTED

Engi

neer

ing

Stan

dard

EARTHWORKS AND FORMATION

ESC 410

Engineering Standard Geotechnical

Version 2.0

Issued July 2010

Owner: Principal Engineer Geotechnical

Approved by: John Stapleton Authorised by: Jee Choudhury A/Principal Engineer Principal Engineer Technology & Standards

Disclaimer

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RailCorp Engineering Standard — Geotechnical Earthworks and Formation ESC 410

© Rail Corporation Page 2 of 16 Issued July 2010 2.0 UNCONTROLLED WHEN PRINTED Version

Document control Revision Date of Approval Summary of change

2.0 July, 2010 Changes detailed in Summary table below

1.2 December, 2009 Change of format for front page, change history and table of contents; Minor editing and formatting throughout

1.1 October, 2007 New section 11 on ground anchors to be consistent with ESC 350.

1.0 September, 2006 First issue as a RailCorp document. Replaces C 1100, TS 3421, TS 3422

Summary of changes from previous version Section Summary of change

Document Control

Version control updated

3 Additional definitions included

4 Old section 4 “Width of property” deleted; new Section 4 with additional requirements for design, assessment and documentation including design flood level and requirements for multiple tracks

5 New Section on design flood level

6 Clarification of requirements for double vs multiple tracks

7 Minor changes to design requirements for cuttings

8 More detailed requirements for embankments including for sampling & testing; drainage blanket; embankment profile and rock facing of embankments

9 Additional design requirements for earthworks near structures

10 New Section on tolerances for earthworks

11 Minor changes to design requirements for capping; update reference to TMC 304 to SPC 301

16 New Section on repair and overhaul of track formation

Appendix 1 Title changed for clarity; note added re minimum dimension from edge of cutting face to top drain

Appendix 2 Title changed for clarity; note added re minimum dimension from edge of cutting face to top drain

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Contents 1 Purpose, Scope and Application ............................................................................................................ 4 2 References ................................................................................................................................................ 4

2.1 Australian and International Standards ......................................................................................... 4 2.2 RailCorp Documents ..................................................................................................................... 4 2.3 Other References .......................................................................................................................... 4

3 Definitions................................................................................................................................................. 4 4 Design Requirements .............................................................................................................................. 6

4.1 General .......................................................................................................................................... 6 4.2 Design investigation ...................................................................................................................... 6 4.3 Design flood level .......................................................................................................................... 6 4.4 Formation....................................................................................................................................... 7 4.5 Documentation .............................................................................................................................. 7

5 Cuttings ..................................................................................................................................................... 7 5.1 Excavation ..................................................................................................................................... 7 5.2 Batter Slopes ................................................................................................................................. 8

6 Embankments........................................................................................................................................... 8 6.1 Embankment Material.................................................................................................................... 8 6.2 Compaction Standards .................................................................................................................. 9 6.3 Sampling and Testing.................................................................................................................... 9 6.4 Drainage Blanket ........................................................................................................................... 9 6.5 Embankment Profile ...................................................................................................................... 9 6.6 Rock Facing of Embankments....................................................................................................... 9

7 Capping Layer........................................................................................................................................... 9 8 Earthworks near Structures .................................................................................................................. 10

8.1 General ........................................................................................................................................ 10 8.2 Construction................................................................................................................................. 10 8.3 Excavation ................................................................................................................................... 11

9 Tolerances for Earthworks .................................................................................................................... 11 9.1 Vertical Tolerances...................................................................................................................... 11 9.2 Horizontal Tolerances.................................................................................................................. 12

10 Drainage .................................................................................................................................................. 12 11 Ground Anchors..................................................................................................................................... 12 12 Train Examination Areas ....................................................................................................................... 12 13 Walkways ................................................................................................................................................ 13 14 Rehabilitation of Formation................................................................................................................... 13 Appendix 1 Single Track Cross Section...................................................................................................... 14 Appendix 2 Double Track Cross Section..................................................................................................... 15 Appendix 3 Shoulder Distance ..................................................................................................................... 16

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1 Purpose, Scope and Application This Standard establishes design requirements and acceptance standards for embankments, cuttings and earthworks capping layer.

It is applicable to all RailCorp mainline and siding tracks.

2 References

2.1 Australian and International Standards AS 1289 Methods of testing soils for engineering purposes

AS 4678 Earth retaining structures

2.2 RailCorp DocumentsESC 215 Transit Space

ESC 350 Retaining Walls and Platforms

ESC 420 Track Drainage

SPC 301 Structures Construction

SPC 411 Earthworks Materials

2.3 Other ReferencesNil

3 Definitions Borrow Pit: Excavation made for the procurement of material Capping Layer: Layer of compacted

earthworks. material that provides a sealing layer to the

CBR: Soaked California Bearing Ratio, determined on a compacted sample.

Cohesionless Soil: Material consisting mostly of sand and gravel mixture, generally with less than 5% fines (i.e., particles finer than 75 μm diameter).

Cohesive Soil: Material consisting mostly of silt and clay and has a well-defined moisture-density relationship when tested in accordance with AS 1289.5.1.1 or AS 1289.5.2.1.

Collapsible Soil: Soil that may suffer a significant decrease in volume under load or when it becomes nearly saturated, which may have existed in thismetastable state for a long time

Compaction: The process whereby the density of soil is increased by mechanical means. This typically involves, rolling, impact or vibration, or a combination of these processes.

Contaminated Material: Material that may contain toxic substances or soluble compounds harmful to environment, water supply or agriculture.

Cutting: An earth or rock excavation within the works site that is made below an existing surface to create the railway formation.

Dispersive soil: Soil that has the ability to pass rapidly into suspension in the presence of water

Earthworks: The activities covered by this specification

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Earthworks Level: Level at the centre of the earthworks prior to placing of the capping layer.

Embankment: An earth or rock fill structure abovesurface to create the rail track formation.

an

existing and/or excavated

Expansive Soil: Soil that will suffer a high volume change when in contact with water. Any increase or decrease in the moisture content of such soil, would cause swelling or shrinkage, respectively. This type of soil is also called “Reactive Soil” and “Swelling Soil”.

Formation: The earthworks structure including all Foundation, Structural Treatment and Capping Layer, on which ballast is laid

Formation Level: Finished level at the centre of the formation preparatory to laying ballast. It includes the required capping layer.

Formation Width: Width at formation level

Foundation Treatment: A special layer or treated zone at the base of a formation for the purpose of reinforcing, strengthening or drainage.

General Fill: The zone below the structural zone of the embankment.

Geosynthetics: Prefabricated sheet made of polymeric materials which may be permeable or non-permeable. This material may be used as filter-drainage (if permeable) or foundation reinforcement. It includes geotextile, geonet, geogrid and geocell.

Geotechnical Engineer: RailCorp’s Principal Geotechnical Engineer or a competent person with delegated engineering authority for geotechnical design activities relating to earthworks.

Rail Level: Theoretical level of the running surface of the rails. In the case of superelevated track, it is the low rail.

Relative Compaction:

For cohesive soils, the dry density ratio determined in accordance with AS 1289.5.4.1, or the Hilf density ratio determined in accordance with AS 1289.5.7.1.

For cohesionless soils, the density index determined in accordance with AS 1289.5.6.1.

Relative Density: The field dry density expressed in terms of maximum/minimum densities established by laboratory test (used for cohesionless soils). The specific minimum value should be determined with the Earthworks Specifications.

Right of Way: The strip of land over which railroads are built.

Rockfill: Fill compacted almost exclusively of fragments of broken rock. It generally consists of a large portion of gravel, cobble, and larger sized fragments, and may contain large open voids.

Shoulder Distance: Distance from the track centreline to the edge of the formation.

Soluble Soil: Soil containing perishable particles such as gypsum or rock salt.

Stockpile: Placement of material that has been selected, loaded, transported and unloaded in a heap outside the confines of a borrow pit or of an excavation that forms part of the works.

Structural Zone: The upper zone of the embankment. Its thickness varies from 500 mm to 1000 mm, depending on the CBR of the general fill.

Tolerance: Range between the limits within which a dimension or position lies.

Top Soil: A natural surface soil that may contain organic matter.

Unsuitable Material: The material that occurs in the borrow site or below the foundation level of embankment and is not considered as suitable due to its adverse

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characteristics as specified in Clause 8.

4 Design Requirements

4.1 GeneralEarthworks and formation design includes:

− cuttings

− embankments

− capping layer.

New lines shall be constructed on a corridor wide enough to accommodate earthworks and formation designed and constructed in accordance with the requirements in this document. The corridor shall also accommodate associated drainage and access roads as detailed in relevant RailCorp engineering standards.

4.2 Design investigationBefore any earthwork activity is undertaken, necessary assessment and investigation shall be carried out to determine the nature, elements and extent of the work.

In the preliminary assessment, planning and design of earthworks, the following items shall be considered:

− Site investigation

− Adjoining property

− Preservation items

− Rehabilitation

− Drainage

− Erosion and siltation

− Sloping ground

− Slope stability

− Cuttings and trenches

− Retaining walls

− Problematic soils requiring special consideration including reactive (expansive) soils, dispersive soils, collapsible soils, soluble soils, soft-compressible soils, and potential acid or sulfate soils.

− Compaction moisture content

− Surcharging of slopes

− Calculation of quantities

− Geosynthetics (Geotextile, Geogrid, etc.)

− Construction vibrations

− Non-potable water to be used for soil compaction

− Contamination

4.3 Design flood level Where track is on a flood plain, the formation level shall be designed so that it is not overtopped in a 1 in 100 year flood, subject to environmental impact assessment in accord with legislation and assessment of the impact of potential flooding on earthworks and other structures.

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4.4 FormationFormation is the earthworks structure including all foundation, structural treatment and capping layer on which ballast is laid.

The formation for single track mainlines and single track sidings shall comply with the appropriate dimensions shown in Appendix 1.

The formation for double track mainlines and double track sidings shall comply with the appropriate dimensions shown in Appendix 2.

The formation for multiple track mainlines and multiple track sidings shall comply with the appropriate dimensions shown in Appendix 2, subject to the requirement that the water from one track shall not cross another track to get away. For example, if there are three tracks, there shall be at least one subsurface centre drain.

Shoulder distances shall comply with Appendix 3.

Track centres shall be in accordance with ESC 215 “Transit Space”.

Where reduced shoulder distances exist due to physical constraints, an assessment is to be made of the need for safety refuges, handhold devices and limited clearance signs. The requirements are specified in ESC 350 “Retaining Walls and Platforms”.

4.5 DocumentationAll activities of earthworks shall be documented. Appropriate documents should be prepared in the following stages:

− Investigation and planning;

− Design and specification;

− Construction.

5 CuttingsDesign of cuttings shall provide for excavation of material within the limits of the batters including benching and terracing of cut batters; cleaning of batter surfaces; treatment of cutting floors; and foundation treatment below the embankment. Cuttings in both soil and rock should provide a stable, safe foundation for the structure.

Benching in cuttings will be provided in both soil and rock as necessary.

5.1 ExcavationExcavation shall be carried out to the lines, levels, dimensions and slopes shown on the Drawings.

The excavated faces shall be neatly trimmed and the top edges of the cuttings neatly rounded.

Under cutting of the slopes shall not be permitted under any circumstances.

Excavation shall be carried out in such a manner as to prevent erosion or slip; working faces shall be limited to safe height and slopes, and surfaces shall be drained to avoid ponding and erosion.

Batters will generally require fattening at the ends of cuttings owing to the presence of less stable material. In all cuttings, undulations in the general plane of the batter shall not be permitted.

Overhanging and loose or unstable materials likely to slip shall be cut back, removed or stabilised.

Rock cuttings and exposed surfaces shall be excavated so as to obtain smooth, uniformly trimmed surface.

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Excavation at the base of cutting shall be finished at a level to suit the capping thickness, with cross falls and cess drains provided.

Prior to placing formation materials and carrying any designed foundation treatment, the cutting floor shall be tested and inspected by the Geotechnical Engineer.

5.2 Batter SlopesBatter slopes in soil and rock cuttings in excess of 3 m high and closer than 6 m from the track centreline, shall be determined on the advice of the Geotechnical Engineer.

Unless shown otherwise on the Drawings or as advised above, cutting slopes should be in accordance with the following guidelines:

Slope Material

Horizontal Vertical

1 Sand 2 2.5 1.0

2 Clay, loose gravel 2.0 1.0

3 Sandy clay, boulder clay, compacted gravely soil, talus 1.75 1.0

4 Highly jointed, weathered rock 1.5 1.0

5* Sound shale dipping sharply towards railway formation, tight cemented gravel 1.0 1.0

6* Ordinary rock 1.0 1.0

7* Solid well bedded rock 0.25 1.0 * Maximum height without bench – 7 m.

* Batter slopes in rocks shall be confirmed by the Geotechnical Engineer.

Slopes shown on the Drawings represent the estimated requirements for the expected types of material and will be subject to re-determination on the basis of site inspection and investigation during excavation. Where necessary, advice shall be obtained from the Geotechnical Engineer.

6 Embankments

6.1 Embankment MaterialEmbankment materials shall comply with Engineering Specification SPC 411 Earthworks Materials.

Embankments are earthfill or rockfill structures above an existing and/or excavated surface to create the rail track formation.

The embankment shall consist of two zones of embankment material:

− General Fill

− Structural Zone.

General fill is the embankment below the structural zone.

The structural zone is the fill at the top of the embankment.

The thickness of the structural zone (H) is determined by the following relationship with the general fill in the embankment:

− for general fill with CBR* of 3 to 8%, H = 500 mm

− for general fill with CBR* of 1 to 3%, H = 1000 mm.

* (Soaked California Bearing Ratio, Standard Compaction).

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Material for use in the structural zone shall comply with SPC 411.

6.2 Compaction StandardsTo achieve a stable and durable embankment, the material shall be prepared and compacted as specified below.

The Compaction standards shall be as follows:

Compaction A: - Cohesive soils - Not less than 100% maximum dry density as determined by AS.1289 Tests 5.1.1 and 5.3.1 (Standard Compaction)

- Rock fill or cohesionless soils - No visible deflection of surface under 10 tonne vibratory rollers after 6 to 8 passes.

Compaction B: Not less than 95% maximum dry density as determined by AS.1289 Tests 5.1.1 and 5.3.1 (Standard Compaction).

Embankments shall be compacted to:

General Fill: Compaction B

Structural Zone: Compaction A

6.3 Sampling and Testing After compaction of each layer, sampling locations will be selected for moisture content and relative density tests.

Field (in-situ) density and laboratory tests shall be carried out in accordance with Australian Standards. The test results must be representative of the tested layer at its full depth, width and length.

Proof rolling shall be carried out on all layers to detect any possible soft or unstable pocket.

6.4 Drainage BlanketWhere specified or directed by the Geotechnical Engineer, a free draining filter layer consisting of hard durable crushed rock, river gravel or slag which is called drainage blanket, shall be provided under the embankment.

6.5 Embankment ProfileEmbankment batter slopes up to a height of 3 meters, shall be 2:1 (horizontal: vertical). For higher embankments, the batter slopes shall be determined by stability analysis taking into account of materials properties, height, foundation conditions, static and dynamic loading, and potential seepage forces. Advice shall be sought from the Geotechnical Engineer if there is any doubt concerning the embankment stability.

The completed batter must be free of rills running down the face of batter. Any loose material on the batter shall be promptly removed as the work progresses.

6.6 Rock Facing of Embankments Where shown on the Drawings, embankment batters (including embankments at bridge structures) shall be provided with a facing of clean, hard, durable rocks (Rip-rap) separated from the earth fill embankment with a graded filter or geotextile sheet in accordance with specifications given by SPC 411. Rock facing shall be placed outside of the general embankment dimensions.

7 Capping LayerCapping is a compacted layer from selected materials that provides seal to the earthwork underneath. The capping layer shall be constructed in a single layer having a compacted thickness of minimum 150 millimetres.

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The material shall be spread in uniform horizontal layer so as to achieve the specified compacted thickness for the full width of the capping layer. Capping is to be laid on subgrade with a minimum CBR of 8%.

Capping material shall comply with Engineering Specification SPC 411 Earthworks Materials.

Compaction shall achieve a minimum dry density of 95 per cent Maximum Dry Density as determined by AS 1289, Test 5.2.1.

The capping material shall be well mixed throughout the layer so that all voids are filled. The top of the final layer shall be graded and trimmed, and material shall be added as necessary to produce an even sealing layer.

8 Earthworks near Structures

8.1 GeneralFor the purpose of this Clause, structures include bridge piers and abutments, wing walls, box culverts, pipe culverts, headwalls, tunnels, retaining walls, platform walls, overhead wiring structures, signal gantries and towers.

8.2 ConstructionCare shall be exercised in constructing earthworks within 5m of structures to avoid damage to the structures.

Non-vibratory compaction equipment shall be used within this distance and adjacent to the structure as defined in the following table:

Structure Compaction Method

Bridge abutment and wing walls

Hand held compaction equipment for full structure height for a distance of 2/3 H from wall (H = overall height of structure)

Pipe Culverts Hand held compaction equipment for distance D from pipe to top of pipe (D= diameter of pipe)

Box culverts & culvert wing walls & retaining wall

Hand held compaction equipment for full structure height for a distance 2/3 H from wall (H = overall height)

Compaction of earthworks near structures

Selected backfill shall be placed adjacent to structures in accordance to the following table. The selected backfill shall consist of a granular material having a maximum dimension not exceeding 50 mm and a plasticity index, determined in accordance with AS 1289.3.3.1, neither less than 2 nor more than 12. In the table, H = overall height of the structure.

Selected Backfill Structure Type

Width Height

Bridge Abutments 2 m H

Box Culverts, Precast Culverts H/3 H + 300 mm

Corrugated Steel Pipes and Arches 0.5 m H + 500 mm

Retaining Walls H/3 H

Select fill adjacent to structures

The fill shall be placed in horizontal layers with a compacted thickness between 100 mm and 150 mm.

Layers shall be placed simultaneously on both sides of box culverts to avoid differential loading.

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Compaction shall start at the wall and proceed away from it.

The existing slope behind the structures shall be cut in the form of successive horizontal terraces, each terrace being at least 1 meter in width and 600 mm in height.

In case of spill-through abutments, rocks shall not be dumped against the columns or retaining walls but shall be built up evenly by hand placing around or against such structures.

In the case of framed structures, embankments at both ends of the structure shall be brought up simultaneously and the difference between the levels of the embankments at the respective abutments shall not exceed 500 mm unless otherwise specified in the Drawings or within the specifications.

Adjacent to weep holes, free draining filter material encapsulated in a suitable geotextile fabric should be placed, horizontally for at least 300 mm from, and vertically for 450 mm above the weep - hole. Free draining material must be provided by broken stone or river gravel consisting of clean, hard, durable particles graded from 50 mm to 10 mm such that:

− the maximum particle dimension does not exceed 50 mm; and

− no more than 5% by mass passes the 9.5 mm AS sieve.

8.3 ExcavationCare should also be exercised when excavating within 5m of structures (for example near overhead wiring structures when benching into slopes for embankment widening or when excavating for track reconditioning).

When excavating adjacent to structures, there is a risk that the footings may be undermined or the structure destabilized, resulting in structural failure and potential collapse.

Excavations in the vicinity of structure footings are therefore not permitted unless documented engineering advice and approval are obtained.

No excavation should be made within this 5m distance without prior analysis of structure stability with respect to the effects of the excavation.

No excavation shall be made below the base of the footings of any structure (for example bridges, retaining walls and station platform walls) without prior analysis of structure stability with respect to the effects of the excavation.

The approval will be in the form of a certification by a competent geotechnical/structural engineer with relevant engineering authority, based on the results of an appropriate geotechnical and/or structural investigation.

9 Tolerances for Earthworks Tolerances for different sections of earthworks shall comply with the following provisions:

9.1 Vertical Tolerances9.1.1 In embankments

− Top of the structural zone + 0 mm to – 50 mm

− Top of the general fill zone + 40 mm to – 40 mm

9.1.2 In cuttings− Floor of cut (top of common earthworks): other than rock + 40 mm to – 40 mm

− Floor of cut (top of common earthworks): rock + 0 mm to – 80 mm

− Top of Structural Zone: other than rock + 0 mm to – 50 mm

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9.1.3 At transitions between cut and fill − Floor of cut to fill transition +0 to –50mm

9.1.4 Top of benches and berms− Top of benches and berms +50 to –50mm

9.1.5 Capping layer− The finished surface of the capping shall be within 25mm of the level shown on the drawings

and:

∼ The algebraic difference of the deviations from the correct level for any two points 20 metres apart on the centreline shall not exceed 15mm.

∼ The deviation from a three (3) metre straight edge laid on the surface parallel to the centreline shall not exceed 10mm.

9.2 Horizontal TolerancesBase at top of cuts and fills, widths of benches and berms shall not to be less than specified dimensions. Maximum positive tolerance is 300 mm, unless approved by the Geotechnical Engineer.

The width of the capping layer from the design centreline to the finished top of embankment slopes or toe of batters in cuttings shall be not less than the dimensions required by Appendix 3.

When the capping layer is tested with a three (3) metre straight edge laid perpendicular to the centre line the deviation from design profile shall not exceed 10mm concavity.

10 DrainageCess drains; sub-surface drains, top drains and interceptor drains shall be provided for cuttings and are to comply with the requirements in ESC 420 “Track Drainage”.

11 Ground AnchorsGround anchors shall have a design life of 100 years.

Ground anchors shall comply with the requirements of AS 4678 “Earth-retaining structures” and Technical Specification S38 “Permanent Rock Anchors” in RailCorp Engineering Specification SPC 301 “Structures Construction”.

The design of ground anchors shall include mitigation against the effects of stray currents.

The designer shall specify requirements for testing. Test procedures shall comply with Technical Specification S38.

The designer shall specify requirements for long term monitoring, if any.

Anchor heads shall be protected so as not to be an obstruction. They shall be recessed or protected by a continuous smooth surface of shotcrete, concrete etc.

Ground anchors shall not extend under private property without the approval of the Chief Engineer Civil.

12 Train Examination Areas Where nominated, train examination areas are to be provided. The minimum requirement is to cover these areas with a 50mm layer of 10mm single sized aggregate as shown in Appendices 1 and 2.

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The train examination area is not to be assumed as available for road access purposes.

13 WalkwaysWhere nominated, walkways are to be provided for staff to walk along the track cess. The minimum requirement is to cover walkways with a 50mm layer of 10mm single sized aggregate as in Appendices 1 and 2.

14 Rehabilitation of Formation In rehabilitating the formation, the following shall be taken into account when preparing the work plan and design:

− Investigation and assessment of ground condition;

− Rectification of drainage deficiencies;

− Removal and disposal of failed ballast to the formation level;

− Removal and disposal of failed formation material;

− Provision of Capping Material on the original formation;

− Provision of trench (ballast filled) drains;

− Repair/rectification of degraded, ineffective, blocked or sagging culverts.

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Appendix 1 Single Track Cross Section

CL

Shoulder Distance Shoulder Distance

Rail Level 1.5 :11.5 :1

1 in 301 in 30

Batter Slope

Earthworks Level Formation Level

Capping Layer

Ballast

SurfaceNatural

1 in 10

1000 min.


EMBANKMENT

Batter Slope

1.5 :11.5 :1 Ballast

CL

1 in 301 in 30

Batter S

lope


Capping Layer

EARTHROCK

1000 min

Where space permits, increase this distance to allow for mechanized

ipment.maintenance equ

Top drain

Cess drain Additional area to be used for drainage where grade in cutting is less than 1 in 200 or where additional drainage is required.

CUTTING

1 in 30

CL

1.5 :1 1.5 :1 1 in 30

50 min. 1250

Earthwork LevelFormation Level

Rail Level

Typical section where shunters’ and guards’ walkways are required.

Capping Layer

1 in 30 1 in 30


Typical section where examinations areas are specified.

SPECIAL WIDTH REQUIREMENTS

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© Rail Corporation Page 15 of 16

Appendix 2 Double Track Cross Section

Issued July 2010 2.0 UNCONTROLLED WHEN PRINTED Version

1000 min.

Batter SlopeSurface

Formation Ballast 1.5 :1

Capping Natural

1.5 :1 1 in

Shoulder Distance

1 in 10

Shoulder Distance

Earthworks Level

Rail Level

Track Centres

1.5 :1

EMBANKMENT

1.5 :1

Track Centres

Ballast

CUTTING

Batter S

lope

Shoulder Distance

Where space permits, increase this distance to allow for mechanized maintenance equipment.

1000 min.

Shoulder Distance

Batter Slope

ROCK

1 in 30

Capping Layer EARTH

Cess Drain Additional area to be used for drainage where grade in cutting is less than 1 in 200 or where additional drainage is required.

Top Drain

Subsurface Drain

1 in 30 1 in 30

3 :1 3 :1

Surface Drain

CENTRE DRAIN

1 in 30

1.5 :1 1.5 :1

1 in

Capping

Shoulder Distance

1 in 30 1.5 :1

50 min.

Typical section where shunters’ and guards’ walkways are required.

Capping

1 in 30

Shoulder

SPECIAL WIDTH REQUIREMENTS

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Appendix 3 Shoulder Distance

Shoulder distance

Plain track mm

Main line (Electrified or non-electrified) 4250

Siding (Electrified) 4250

Siding (non-electrified) 3000

Main line or siding with parallel access road (Electrified) 6200

Main line or siding with parallel access road (Non-electrified) 5500

Special Requirements

Shunters and guards parallel walkways 4250

Train Examination areas 5500

Train Examination areas with parallel access road 7750

Clear width of road from back of any structure 3000