t hr ci 12072 st track slabs - transport for nsw · a track slab is a reinforced concrete slab that...

Track Slabs

T HR CI 12072 ST

Standard

Version 2.0

Issue date: 17 December 2019

© State of NSW through Transport for NSW 2019

T HR CI 12072 ST Track Slabs Version 2.0


Important message This document is one of a set of standards developed solely and specifically for use on

Transport Assets (as defined in the Asset Standards Authority Charter). It is not suitable for any

other purpose.

The copyright and any other intellectual property in this document will at all times remain the

property of the State of New South Wales (Transport for NSW).

You must not use or adapt this document or rely upon it in any way unless you are providing

products or services to a NSW Government agency and that agency has expressly authorised

you in writing to do so. If this document forms part of a contract with, or is a condition of

approval by a NSW Government agency, use of the document is subject to the terms of the

contract or approval. To be clear, the content of this document is not licensed under any

Creative Commons Licence.

This document may contain third party material. The inclusion of third party material is for

illustrative purposes only and does not represent an endorsement by NSW Government of any

third party product or service.

If you use this document or rely upon it without authorisation under these terms, the State of

New South Wales (including Transport for NSW) and its personnel does not accept any liability

to you or any other person for any loss, damage, costs and expenses that you or anyone else

may suffer or incur from your use and reliance on the content contained in this document. Users

should exercise their own skill and care in the use of the document.

This document may not be current and is uncontrolled when printed or downloaded. Standards

may be accessed from the Transport for NSW website at www.transport.nsw.gov.au

For queries regarding this document, please email the ASA at [email protected] or visit www.transport.nsw.gov.au © State of NSW through Transport for NSW 2019

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



Standard governance

Owner: Lead Civil Engineer, Asset Standards Authority

Authoriser: Chief Engineer, Asset Standards Authority

Approver: Executive Director, Asset Standards Authority on behalf of the ASA Configuration Control Board

Document history

Version Summary of changes

1.0 First issue 30 June 2015

2.0 Second issue. Changes include; general revision of the content; updates to referenced documents; guard rail requirements removed and references added to T HR CI 12071 ST Guard Rails for guard rail requirements; addition of durability requirements; updates to environmental and sustainability requirements; addition of electrical requirements; addition of pavement design requirements; addition of fatigue requirements; and rearrangement of the order of requirements.

© State of NSW through Transport for NSW 2019 of 30



Preface The Asset Standards Authority (ASA) is a key strategic branch of Transport for NSW (TfNSW).

As the network design and standards authority for NSW Transport Assets, as specified in the

ASA Charter, the ASA identifies, selects, develops, publishes, maintains and controls a suite of

requirements documents on behalf of TfNSW, the asset owner.

The ASA deploys TfNSW requirements for asset and safety assurance by creating and

managing TfNSW's governance models, documents and processes. To achieve this, the ASA

focuses on four primary tasks:

• publishing and managing TfNSW's process and requirements documents including TfNSW

plans, standards, manuals and guides

• deploying TfNSW's Authorised Engineering Organisation (AEO) framework

• continuously improving TfNSW’s Asset Management Framework

• collaborating with the Transport cluster and industry through open engagement

The AEO framework authorises engineering organisations to supply and provide asset related

products and services to TfNSW. It works to assure the safety, quality and fitness for purpose of

those products and services over the asset's whole-of-life. AEOs are expected to demonstrate

how they have applied the requirements of ASA documents, including TfNSW plans, standards

and guides, when delivering assets and related services for TfNSW.

Compliance with ASA requirements by itself is not sufficient to ensure satisfactory outcomes for

NSW Transport Assets. The ASA expects that professional judgement be used by competent

personnel when using ASA requirements to produce those outcomes.

About this document

This standard details the design requirements for track slabs.

This standard is a second issue. The changes to this version include the following:

• general revision of the content

• updates to referenced documents

• guard rail requirements removed and references added to T HR CI 12071 ST Guard Rails

for guard rail requirements

• addition of durability requirements

• updates to environmental and sustainability requirements

• addition of electrical requirements

• addition of pavement design requirements




• addition of fatigue requirements

• rearrangement of the order of requirements



Issue date: 17 December 2019 Table of contents 1. Introduction .............................................................................................................................................. 8

2. Purpose .................................................................................................................................................... 8 2.1. Scope ..................................................................................................................................................... 8 2.2. Application ............................................................................................................................................. 9

3. Reference documents ............................................................................................................................. 9

4. Terms and definitions ........................................................................................................................... 11

5. Risk and safety ...................................................................................................................................... 12 5.1. Risk assessment .................................................................................................................................. 12

6. Environmental and sustainability requirements ................................................................................ 13 6.1. Green infrastructure ............................................................................................................................. 13 6.2. Sustainability assurance ...................................................................................................................... 13 6.3. Ambient environmental conditions ....................................................................................................... 13

7. Heritage .................................................................................................................................................. 14

8. Approved materials ............................................................................................................................... 14 8.1. New and infrequently used products ................................................................................................... 14

9. Durability requirements ........................................................................................................................ 15

10. Clearances .............................................................................................................................................. 15

11. Track slab system configuration ......................................................................................................... 15 11.1. Prohibited configurations ................................................................................................................. 15 11.2. Width of track slab ........................................................................................................................... 16 11.3. Length of track slab ......................................................................................................................... 16 11.4. Track requirements .......................................................................................................................... 16

12. Drainage requirements ......................................................................................................................... 17

13. Structural design ................................................................................................................................... 18 13.1. Design traffic loads .......................................................................................................................... 18 13.2. Dynamic load allowance .................................................................................................................. 19 13.3. Derailment........................................................................................................................................ 19 13.4. Distribution of rail traffic load ........................................................................................................... 19 13.5. Rigid pavement ................................................................................................................................ 20 13.6. Fatigue design ................................................................................................................................. 22 13.7. Floating track slabs .......................................................................................................................... 23 13.8. Geotechnical requirements .............................................................................................................. 23 13.9. Top (Infill) slab requirements ........................................................................................................... 24

14. Deformations .......................................................................................................................................... 24

15. Transitions ............................................................................................................................................. 24

16. Noise and vibration ............................................................................................................................... 25 16.1. Environmental noise and vibration .................................................................................................. 25 16.2. In-tunnel noise and in-train noise .................................................................................................... 25



Issue date: 17 December 2019 16.3. Performance and maintenance considerations in design ................................................................ 26

17. Provision for services ........................................................................................................................... 27

18. Documentation....................................................................................................................................... 27 18.1. Drawings .......................................................................................................................................... 27 18.2. As-built drawings ............................................................................................................................. 28 18.3. Reports ............................................................................................................................................ 28

19. Electrical requirements ......................................................................................................................... 29

20. Construction .......................................................................................................................................... 29

21. Maintenance ........................................................................................................................................... 30

22. Decommissioning and disposal ........................................................................................................... 30




1. Introduction A track slab is a reinforced concrete slab that supports railway track. The track is typically

directly fixed to the top of the track slab. Track slabs include slabs supported by the ground and

floating slabs supported on elastomeric bearings which are in turn supported on a base slab

bearing directly on the ground. Track slabs can also support ballasted track and embedded rail

systems.

Track slabs are typically constructed either ‘top down’ (rail position set first) or ‘bottom up’ (track

slab set first).

Track slabs may be beneficial in the following situations:

• at locations with limited vertical or horizontal clearance

• within tunnels where ballasted track maintenance is difficult

• to minimise ongoing track maintenance compared to ballasted track

• where the attenuation of noise and vibration is critical, particularly in tunnels

• where vehicles regularly need to cross the track such as at maintenance depots

• for track stiffness transitions such as at bridge approach or to other forms of track support

2. Purpose This document specifies the design, construction, maintenance, refurbishment, and

decommissioning and disposal requirements for new and existing track slabs in the metropolitan

rail area.

2.1. Scope This standard covers the requirements from design through to decommissioning of track slabs

in the metropolitan rail area.

This standard specifies the technical requirements for the following:

• track slabs bearing directly on the ground and floating track slabs

• the interface with track

• the transition between track slabs and ballasted track

This standard does not cover the following slab track:

• directly fixed bridge decks and bridge approach slabs (refer to T HR CI 12020 ST

Underbridges)

• precast and proprietary level crossing systems




2.2. Application This standard applies to all persons and organisations engaged in the provision of services

related to track slabs in the metropolitan rail area. This document applies to both new and

reconstruction of existing track slabs.

In addition to the requirements of this standard, asset decisions take into account the life cycle

cost considerations specified in T MU AM 01001 ST Life Cycle Costing.

When using the standard, if it is considered that the intent of stated requirements is unclear, a

clarification should be sought from the Asset Standards Authority (ASA).

3. Reference documents The following documents are cited in the text. For dated references, only the cited edition

applies. For undated references, the latest edition of the referenced document applies.

International standards

BS EN 16432-1 Railway Applications – Ballastless track systems – Part 1: General

requirements

BS EN 16432-2 Railway Applications – Ballastless track systems – Part 2: System design,

subsystems and components

BS EN 13146-9 Railway application – Track - Test methods for fastening systems. Part 9:

Determination of stiffness

BS EN 13481-2 Railway applications – Track – performance requirements for fastening

systems. Part 2: Fastening systems for concrete sleepers

BS EN 13481-5 Railway applications – Track – performance requirements for fastening

systems. Part 5: Fastening systems for slab track with rail on the surface or rail embedded in a

channel

ISO 14837-1 Mechanical vibration – Ground-borne noise and vibration arising from rail systems

– Part 1: General guidance

Australian standards

AS 5100 Bridge design (all parts)

AS 5100.2:2017 Bridge design – Part 2: Design loads

AS 5100.5 Bridge design - Part 5: Concrete

Transport for NSW standards

ESC 210 Track Geometry and Stability

ESC 215 Transit Space




ESC 230 Sleepers and Track Support

ESC 302 Structures Defect Limits

MN A 00100 Civil and Track Technical Maintenance

SPC 206 Track Construction

SPC 207 Track Monitoring Requirements for Undertrack Excavation

SPC 301 Structures Construction

T HR CI 12002 ST Durability Requirements for Civil Infrastructure

T HR CI 12020 ST Underbridges

T HR CI 12030 ST Overbridges and Footbridges

T HR CI 12070 ST Miscellaneous Structures

T HR CI 12071 ST Guard Rails

T HR CI 12075 ST Airspace Developments

T HR CI 12110 ST Earthworks and Formation

T HR CI 12130 MA Track Drainage

T HR CI 12130 ST Track Drainage

T HR CI 12190 ST Service Installations within the Rail Corridor

T MU AM 01001 ST Life Cycle Costing

T MU AM 01003 ST Development of Technical Maintenance Plans

T MU EN 00005 ST Ambient Environmental Conditions

T MU EN 00007 GU Integrating Green Infrastructure

T MU EN 00008 ST Sustainability Assurance Requirements

T MU MD 00006 ST Engineering Drawings and CAD Requirements

T MU MD 20001 ST System Safety Standard for New or Altered Assets

T MU MD 20002 ST Risk Criteria for Use by Organisations Providing Engineering Services

TN 016: 2015 Overbridges and footbridges – Earthing and bonding requirements

Other reference documents

Austroads, Guide to Pavement Technology (all parts)

Heritage Act 1977

NSW Environment Protection Authority 2013, Rail Infrastructure Noise Guideline




NSW Heritage Office 2005, State Agency Heritage Guide – Management of Heritage Assets by

NSW Government Agencies, publication number HO05/01

NSW Office of Environment and Heritage, State Heritage Register

RailCorp Section 170 Heritage and Conservation Register

RailCorp Section 170 Heritage and Conservation Register – Moveable heritage

Roads and Maritime Services 2017, QA Specification R83 Concrete Pavement Base

Roads and Maritime Services 2018, QA Specification R82 Lean-Mix Concrete Subbase

Roads and Maritime Services 2019, QA Specification B80 Concrete Work for Bridges

SafeWork NSW 2019, Safe design of structures code of practice

Work Health and Safety Act 2011

4. Terms and definitions The following terms and definitions apply in this document:

ASA Asset Standards Authority

BOEF beam on continuous elastic foundation

base slab a slab that is constructed directly on the ground and provides support to the top slab

FEM finite element method

floating slab track system where a designed elasticity is introduced between the ballastless

track system and substrate (BS EN 16432-1)

metropolitan rail area the rail freight network and the rail passenger network within the

metropolitan rail area bounded by Newcastle (in the north), Richmond (in the northwest),

Bowenfels (in the west), Macarthur (in the southwest) and Bomaderry (in the south), and all

connection lines and sidings within these areas, but excluding private sidings

pavement continuous, layered structure that forms a hard and durable surface and it is

designed to provide bearing capacity (BS EN 16432-2)

substrate earthworks embankment, cutting, at-grade or tunnel floor system that lies below the

track slab comprising the sub-base and subgrade materials

RMS Roads and Maritime Services

TfNSW Transport for NSW

top slab concrete slab that provides direct support to the track system, constructed on top of

the base slab




trackform the type of track structure and may be ballasted or non-ballasted

• ballasted trackform comprises ballast, sleepers, rail fastening assemblies and rails

• ballastless trackform comprises concrete slab(s), rail fastening assemblies and rails

5. Risk and safety Safe design is mandated in the Work Health and Safety Act 2011 and shall be incorporated into

the design. Guidance on the safe design of structures is available in the Safe design of

structures code of practice.

The design of track slabs, including the refurbishment of existing track slabs, shall take into

account the safety considerations for construction, operational, maintenance and

decommissioning workers, and the potential users of the structure.

The designer shall establish and implement a design process system that manages safety

across the full life cycle of the structure. The design process system shall be developed in

accordance with T MU MD 20001 ST System Safety Standard for New or Altered Assets.

The safety in design process shall be adopted with risks and hazards identified and managed.

5.1. Risk assessment Risk criteria are contained in T MU MD 20002 ST Risk Criteria for Use by Organisations

Providing Engineering Services.

Track slab risk assessment shall be site-specific and should consider at least the following:

• site condition, including cuttings and embankments

• accident and derailment history at the site

• historical formation failure and track misalignments

• type of trackform and transitions

• type of structure and potential for collapse and train damage

• track clearance to structure supports

• presence of hazards at the site, for example, track turnouts

• track components in the direction of travel, for example, catchpoints, turnouts, slips,

diamonds or scissor crossovers

• track geometry; that is, straight or curved track

• track speed at the location, including out of control speed

• type of rolling stock and frequency




• future usage and growth in patronage

• potential for ground settlements

• seepage of ground water particularly in tunnels

• on-going maintenance issues

Risk assessment shall also include any other relevant site-specific criteria and shall be used to

determine the extent of mitigation required.

Risk assessments shall be submitted for acceptance by the rail infrastructure manager (RIM).

6. Environmental and sustainability requirements Section 6.1 through to Section 6.3 set out the environmental and sustainability requirements

that apply during investigation, design, construction and operational activities.

6.1. Green infrastructure The design of track slabs shall identify opportunities to integrate green infrastructure. For further

guidance refer to T MU EN 00007 GU Integrating Green Infrastructure.

Plant species used in landscaping the precinct around the track slab shall be carefully selected

to ensure that they do not accelerate the deterioration, or prevent the examination of structures.

Only low maintenance species with non-invasive root systems shall be planted on areas

retained adjacent to rail infrastructure.

6.2. Sustainability assurance The design of track slabs shall incorporate solutions to TfNSW key sustainability areas as

outlined in T MU EN 00008 ST Sustainability Assurance Requirements.

6.3. Ambient environmental conditions Track slabs shall be designed to operate under the current and projected environmental

conditions defined in T MU EN 00005 ST Ambient Environmental Conditions.




7. Heritage The Heritage Act 1977 stipulates requirements to protect, maintain and manage environmental

heritage in NSW. The Heritage Ac, 1977 also includes items of archaeological significance. If

changes are proposed to items that have heritage significance, the following shall apply:

• for items listed on the State Heritage Register, the provisions of the Heritage Act 1977 shall

be met

• for items listed on the RailCorp Section 170 Heritage and Conservation Register or the

RailCorp Section 170 Heritage and Conservation Register – Moveable heritage or both, the

principles and relevant guidelines contained within the State Agency Heritage Guide -

Management of Heritage Assets by NSW Government Agencies shall be followed

Where new track slabs are proposed within a heritage listed precinct and in the vicinity of a

heritage listed item, the identified significance of heritage items shall not be compromised.

Heritage fabric shall be protected from damage during construction and activities that follow

construction. If unrecorded or unexpected heritage finds are made during works, the works shall

cease immediately. In this event, heritage advice shall be sought and notification shall be made

in accordance with existing legislation.

8. Approved materials The approved construction material for the structural elements of track slabs is reinforced

concrete.

Steel fibre reinforcement is permitted and shall be in accordance with AS 5100 Bridge design

(all parts).

Reinforced or polymer concrete monoblock railway sleepers (that is, a part sleeper supporting

an individual rail plate only) or reinforced concrete full sleepers that are embedded into track

slabs are approved for use. Polymer concrete monoblocks shall be in accordance with the

requirements of ESC 230 Sleepers and Track Support.

8.1. New and infrequently used products If any products specified in the design documentation that can reasonably be deemed to be new

or infrequently used shall be identified by the designer and referred to the Lead Civil Engineer,

ASA for approval.

The designer shall ensure that the manufacturer, constructor or maintainer of the product

understands any special requirements or practices relating to the use of the product in the rail

environment prior to release of the design documentation. The special requirements shall be

included in the documentation.




Proprietary tracks slab systems require ASA type approval.

9. Durability requirements The durability requirements, including design life, of track slabs shall be in accordance with

T HR CI 12002 ST Durability Requirements for Civil Infrastructure.

Requirements for bearings for floating track slabs shall be the same as that stated for bridges in

T HR CI 12002 ST.

10. Clearances Requirements for horizontal and vertical clearances to structures adjacent to and over the track

are in ESC 215 Transit Space.

11. Track slab system configuration The following track slab system configurations are permitted:

• direct fixation track and ballasted track

• single slab

• base slab with top (infill) slab

• embedded polymer or reinforced concrete monoblocks and embedded full reinforced

concrete sleepers

• floating slab

• type approved proprietary slab systems

To avoid the use of plinths and high packers under the rails, the top surface of a direct fixation

track should be cast parallel to the plane of the design track superelevation in the transverse

direction for each track. This applies to the width of slab that lies between the outer edges of the

rail base plates, as a minimum. In the longitudinal direction, the slab should be cast parallel to

the track vertical alignment.

Requirements for track drainage are in accordance with Section 12.

11.1. Prohibited configurations Track slabs with embedded rail systems are prohibited except at sidings and at maintenance

facilities.

Concrete upstand located between the running rails (four-foot) with a solid surface between

gauge faces as shown in Figure 1 is prohibited in order to reduce the lateral movement of a




derailed train. Also refer to T HR CI 12071 ST for prohibited configurations of concrete

upstands.

Figure 1 - Prohibited configuration of concrete upstand

11.2. Width of track slab The track slab shall extend a minimum width of 500 mm beyond the outermost edge of the rail

baseplate on each side of the track, measured at the level of the slab under the rails.

11.3. Length of track slab Track slab length requirements are as follows:

• The minimum overall length of an individual track slab shall be 20 m, unless otherwise

approved by the Lead Track Engineer ASA. This is to avoid rapid changes in track stiffness

occurring over a short length of track. This requirement does not apply to the length of

track slab between transverse joints spaced at less than 20 m.

• The length of approach slabs, where provided, is in addition to the minimum length.

• Ballasted approach slabs provided at the ends of direct fixed track slabs may be shorter,

but not less than 4 m in length.

• The length limit does not apply to individual slab elements that form part of a floating slab

and proprietary slab system.

11.4. Track requirements The design of track slabs shall incorporate the following track requirements:

• Track slabs shall not be installed as a remedial measure for substandard ballast depth

unless approved by the Lead Track Engineer, ASA. The preferred option is to provide

standard ballast depth by either raising the design rail level or by lowering the track

formation level.

• The ends of track slabs shall not be skewed to the track to avoid uneven axle support.

• The running rails shall be continuous with no mechanical joints within the length of the slab,

unless otherwise approved by the Lead Track Engineer, ASA.

• Rail baseplates on direct fixed slabs shall be located a minimum clear distance of 150 mm

from transverse joints in the slab. © State of NSW through Transport for NSW 2019 of 30



• Rail baseplate fasteners shall be designed to resist any uplift tension forces, and comply

with ESC 230 requirements.

• Welded rail joints on slab track should be avoided.

• Where different trackforms are used; the geometric tolerances at the wheel and rail

interface shall be the same.

• The number of interfaces between ballasted track and track slab should be minimised.

• Short length of ballasted track between track slabs is undesirable for track maintenance

and shall not be less than 20 m, unless otherwise approved by the Lead Track engineer

ASA.

• Where a ballast mat is required for noise and vibration isolation, ballast mat requirements

shall be in accordance with T HR ST 12020 ST. A ballast mat with high noise and vibration

reduction characteristics shall be installed.

• For ballasted track slabs, including approach slabs that are on gradients, the designer shall

mitigate against the potential for ballast creep.

11.4.1. Rail attachment Resilient fastening systems shall be used for running rails on track slabs and shall be approved

fastenings for track slabs in accordance with ESC 230.

Where guard rails are used, refer to T HR CI 12071 ST.

Direct rail fixation attachment shall also comply with the requirements in T HR CI 12020 ST.

11.4.2. Turnouts Where turnouts are designed in the track slab, base plate fasteners shall incorporate cast in

nylon ferrules to allow for quick and easy installation and removal of the turnout. Cast-in anchor

fasteners are prohibited at turnout locations within a track slab.

For turnouts, the rail shall be continuous through the turnout location without the use of

mechanical joints.

Track slabs located under or within 10 m of turnouts and special trackwork shall be approved by

the Lead Track Engineer, ASA.

12. Drainage requirements The designer shall ensure that the drainage system used in the vicinity of a track slab takes into

account the management of water at and below track slab foundation level in order to avoid

upward water pressure forces on the track slab.




The drainage of water, which may flow upward from the sub-grade, shall be facilitated by the

drainage system.

The track drainage system shall be designed in accordance with T HR CI 12130 ST Track

Drainage and the following requirements:

• The surface of the track slab shall be graded to ensure that water is directed into the track

drainage system and not pond on the surface of the track slab.

• Cross-fall in the top surface of the track slab shall be provided to ensure that rail

baseplates and fastenings remain above any ponding water at all times. This also ensures

that water ponding does not occur on track slabs and prevents water entrapment in the

void beneath any floating slab.

• The minimum gradient of the track slab surface shall be 0.5% (1 in 200 slope) in any

direction.

• The drainage system shall accommodate slab movements.

• The depth of run-off water on track slabs shall not interfere with signalling and electrical

equipment.

• The minimum clear depth for a drainage path shall be 100 mm (for example, under rails

and gratings where applicable).

• Additional drainage provisions shall be made to manage the ground water in rock

foundations and cuttings with seepage forces. The presence of bedding planes within the

influence zone of the foundation pressure shall be taken into account.

13. Structural design Track slabs shall be designed in accordance with AS 5100 unless otherwise noted in this

standard.

For track slabs on gradients and or curved horizontal alignment, the designer shall determine

the requirements for anchoring and restraining the track slab to the foundation. This may

include the provision of shear keys and dowel bars where required.

13.1. Design traffic loads The design rail traffic loads for track slabs shall be in accordance with the requirements in

T HR CI 12020 ST for underbridges.

Load factors and load combination shall be in accordance with AS 5100.

Braking and traction forces shall be determined in accordance with T HR CI 12020 ST.

Fatigue design traffic loads shall be in accordance with Section 13.6.1.




13.2. Dynamic load allowance The dynamic load allowance, α, is defined in AS 5100.2:2017 Bridge design – Part 2: Design

loads and shall be in accordance with Table 1.

Table 1 – Dynamic load allowance

Rail traffic DLA, α, to AS 5100.2:2017

Freight 0.67

Passenger only 0.5

General yard freight 0.33

Passenger stabling and maintenance facilities

0.0

13.3. Derailment Track slabs shall be designed for the derailment load cases specified in AS 5100 using the

design traffic loads specified in Section 13.1.

The need for derailment containment devices and protection (that is, guard rails, deflection

kerbs and deflection barriers) shall be determined by the requirements of risk assessment in

accordance with Section 5.1. The requirement for protection of trackside structures is in

accordance with the following standards:

• T HR CI 12030 ST Overbridges and Footbridges

• T HR CI 12070 ST Miscellaneous Structures

• T HR CI 12075 ST Airspace Developments

Where derailment containment devices are required, they shall be provided in accordance with

T HR CI 12020 ST and T HR CI 12071 ST.

13.4. Distribution of rail traffic load The distribution of rail traffic load to the track slab (pavement) shall be calculated using a

rigorous analysis that takes into account the relative stiffness of the rail, the rail fixing supports,

ballast where present, the slab and substrate.

Where embedded sleeper or monoblock items are used in the track slab, the structural depth of

the slab shall take into account the degree to which the embedded item is bonded to the slab.

Where embedded sleepers or monoblocks are supported on resilient pads or by resilient boots,

the structural depth shall be measured from the top of the slab at the underside of the resilient

pad or boot.




Track slab system shall take into account the interaction with the track, the vertical and

horizontal stiffness and the effects of the following components:

• rail

• rail baseplate and fastening assemblies

• ballast, where present

• prefabricated elements (monoblocks, sleepers)

• top or infill slab

• bearing pads, where present

• base slab (pavement)

• substrate earthworks (subbase and subgrade)

• traction and braking forces from rail traffic

• movement joints in both the rail and slab

• transition arrangements

The following load distribution models may be used to determine design actions in the slab

pavement:

• slab and beam on continuous elastic foundation (BOEF)

• slab on elastic supports using finite element method (FEM)

Where FEM models are used, the results should be calibrated and verified against traditional

design methods.

Refer to the following documents for guidance on load distribution methods:

• BS EN 16432-1 Railway Applications – Ballastless track systems – Part 1: General

requirements

• BS EN 16432-2 Railway Applications – Ballastless track systems – Part 2: System design,

subsystems and components

13.5. Rigid pavement Track slabs shall be designed using rigid pavement beam on elastic foundation design

methodology.

The pavement design shall take into account the following:

• soil-structure interaction

• effects of traffic on joints due to maintenance vehicles




• joint spacing and layout details (for example block-outs)

• differential movement at joints

• construction, expansion and contraction joints as appropriate

• odd-shaped slab and slab shape-factor design requirements

• moisture passing through the slab or pavement

• the effect of water pressure where present

• control of cracking

• control of shrinkage warping

• differential temperature effects

• boundary conditions (ends and sides of the track slab)

• fatigue

• noise and vibration isolation (particularly in tunnels)

Refer to the following documents for guidance on design of rigid track slab pavements and

pavement fundamentals:

• BS EN 16432-2

• Guide to Pavement Technology (all parts)

13.5.1. Pavement requirements The following concrete pavement slab types may be used for track slabs:

• continuously reinforced concrete pavement (CRCP)

• jointed reinforced concrete pavement (JRCP)

• reinforced concrete pavements (SFCP) with steel fibres and joints where supported on

base slab, and with joints and conventional reinforcement where not supported on a base

slab

Jointed plain concrete pavement (JPCP) shall not be used.

Pre-stressed concrete pavement (PCP) shall only be used with approval from the Lead Civil

Engineer ASA.

Synthetic fibre reinforcement may be added and used for supplementary shrinkage crack

control only and shall not be used as a replacement for steel reinforcement.



Issue date: 17 December 2019 13.5.2. Joints

Joints in concrete slabs shall comply with the following:

• transverse movement and construction joints shall be dowelled using stainless steel dowel

bars or tied using stainless steel tie bars

• longitudinal joints are not permitted except mid-way between tracks

• longitudinal joints shall be tied using stainless steel tie bars

• movement joints shall be sealed at the surface

13.6. Fatigue design Fatigue shall be included in the design of track slabs. Fatigue design shall be in accordance

with AS 3600 and as noted in this standard. AS 3600 has more up to date fatigue provisions

than AS 5100.5 Bridge design - Part 5: Concrete.

Permanent actions shall be determined in accordance with AS 5100.

13.6.1. Fatigue design load The fatigue design actions shall be in accordance with the following:

• for 300LA, refer to Section 13.1

• for 200LA passenger lines, the fatigue design traffic load shall be in accordance with

T HR CI 12020 ST

Half of the dynamic load allowance specified in Section 13.2 shall be used with the fatigue

design load.

13.6.2. Effective number of fatigue stress cycles The effective number of fatigue stress cycles shall be determined based on the following:

• For mainlines carrying freight traffic (300LA design load as defined in AS 5100, or higher),

the effective number of fatigue stress cycles shall be calculated in accordance with

AS 5100. The value for equivalent number of stress cycles may be estimated using a value

for nT from Table 9.8.3 of AS 5100.2:2017 equal to 240 (corresponding to a span less than

2.5 m).

• For mainlines carrying passenger traffic (200LA design load, modified 300LA), the effective

number of fatigue cycles shall be determined in accordance with T HR CI 12020 ST.



Issue date: 17 December 2019 13.6.3. Fatigue combination load case

AS 5100 and AS 3600 do not provide serviceability combination load cases that include fatigue.

Where the designer calculates the thermal effects in the concrete slab to be significant, the

designer shall determine the maximum allowable flexural fatigue stress due to rail traffic in

combination with serviceability thermal effects. A recognised method shall be used, for

example, BS EN 16432-2 provides requirements for maximum allowable tensile flexural fatigue

stress in combination with thermal stress.

Thermal gradients shall be in accordance with AS 5100.

13.7. Floating track slabs Additional requirements for the design and installation of floating slabs are as follows:

• dynamic deformations shall not cause the transit space to be compromised

• dynamic behaviour of the floating slab shall not act adversely with the vehicle suspension

modes, resulting in increased wear of any component or a reduction in ride quality

• drainage of the track slab shall be provided in accordance with Section 12 of this document

• bearings supporting the track slab may comprise full surface contact bearing strips over the

design width or be individual bearings pads,

• bearings shall be shall be designed in accordance with AS 5100

• the design life of the bearings shall be in accordance with Section 9 of this document

• provision shall be made for inspection, maintenance and replacement of bearings within a

limited track possession time

• adequate air gap shall be provided beneath the floating slab to avoid acoustic coupling

effects, unless full surface contact bearing strip is provided

• all gaps between structural elements shall be effectively covered to prevent debris from

entering the gaps and the covers shall be removable for inspection purposes

• the maximum step-down height from the track slab shall be 150 mm

13.8. Geotechnical requirements The design of the substrate earthworks (subbase and subgrade) shall be based on the results

of geotechnical investigations to ensure that a continuous uniform support of the track slab

structure is provided.




Substrate materials shall be selected in accordance with the following:

• relevant Roads and Maritime Services (RMS) road pavement specifications

• SPC 301 Structures Construction

• T HR CI 12110 ST Earthworks and Formation

Lean mix concrete is a permissible subbase material for track slabs. Lean mix concrete used as

a subbase material shall be in accordance with the requirements of QA Specification R82 Lean-

Mix Concrete Subbase.

The substrate shall be designed to prevent the infiltration of water under the track slab and to

mitigate against the adverse effects of high-water tables.

The design shall take into account seepage forces at foundation level.

The design shall take into account the presence of bedding planes in rock foundation within the

influence zone.

13.9. Top (Infill) slab requirements A top (infill) slab shall be adequately restrained laterally and anchored down to the base slab to

ensure that de-bonding does not occur as a result of the following:

• dynamic uplift effects

• thermal or shrinkage effects

• downhill creep or slip effects

14. Deformations The design of the track slab shall ensure that slab movement and deformations do not

adversely affect the integrity of other infrastructure such as track and signalling.

Movements shall not result in the track geometry being outside the limits as specified in

ESC 210 Track Geometry and Stability.

15. Transitions Transition zones are locations where a railway track changes from ballasted track on formation

to track on a stiffer support such as a track slab.

Transition regions usually require more frequent track maintenance resulting from settlement

due to the increase in dynamic forces.

The purpose of an effective track transition is to avoid abrupt change in track stiffness.




Where a direct fixation track slab interfaces with ballasted track, a transition slab shall be

designed to meet the following requirements:

• provide a progressive change in track stiffness (for example, variable depth of ballast over

the length of the transition slab and/or variable stiffness in resilient rail baseplates)

• have a minimum length of 4 m

• designed for the same loads and deformations as the track slab

• provide continuity of drainage between the track slab drainage and track drainage

• the track alignment accurately matched under all load conditions, in order to avoid stress

concentrations in components or uneven ride characteristics

• comply with the nominated levels of vibration and regenerated noise attenuation

• the number of transition sections are minimised

• transition section is maintainable that does not result in differential settlement

• ballasted track on the transition slab in accordance with TfNSW track engineering

standards

Refer to BS EN 16432-1 for more information on transitions and T HR CI 12020 ST for track

transitions and approach slabs.

16. Noise and vibration Noise and vibration arising from track slabs is a highly complex issue. Section 16.1 through to

Section 16.3 describes the key noise and vibration concepts to be considered in the design of

track slabs.

16.1. Environmental noise and vibration Noise and vibration from trains operating on track slabs at sensitive locations such as

residences shall comply with the Rail Infrastructure Noise Guideline. Project specific limits, for

example, in conditions of approval shall also be complied with.

Where assessment and mitigation of ground-borne noise and vibration is required,

methodologies shall be consistent with those defined in ISO 14837-1 Mechanical vibration –

Ground-borne noise and vibration arising from rail systems – Part 1: General guidance.

16.2. In-tunnel noise and in-train noise To reduce ground-borne noise, rails are often mounted on a floating track slab or with resilient

rail fasteners for conventional slab. This limits the amount of vibration from the wheel and rail

interface which enters the ground.




The design of track slabs in tunnels or enclosed structure environments shall take into account

the operational air-borne noise within the enclosed environment.

Refer to the following for additional information:

• BS EN 13146-9 Railway application – Track - Test methods for fastening systems. Part 9:

Determination of stiffness

• BS EN 13481-2 Railway applications – Track – performance requirements for fastening

systems. Part 2: Fastening systems for concrete sleepers

• BS EN 13481-5 Railway applications – Track – performance requirements for fastening

systems. Part 5: Fastening systems for slab track with rail on the surface or rail embedded

in a channel.

16.3. Performance and maintenance considerations in design The design shall take into account flexural vibration and noise radiation.

Where a floating track slab is used to mitigate noise and vibration effects, it shall be of a proven

design with demonstrated performance and be suitable for the operating environment in the

metropolitan rail area.

Ground-borne noise and vibration is likely to have a significant bearing on the tunnel alignment

and track design. Operational and maintenance issues that may influence ground-borne noise

and vibration from tunnels should be considered, including the following:

• track design features such as curves and crossovers, which increase the levels of ground-

borne vibration generated at source

• track bed vibration isolation system shall be optimised for operation with the rolling stock

that is required to operate on the track

• ongoing maintenance of rolling stock, particularly wheels

• ongoing maintenance of track, particularly the rail running surface

The selection and design of track slab support systems for ground–borne noise and vibration

control requires careful consideration of maintenance and performance aspects.

Particular consideration should be given to the following:

• modes of vibration of floating slab elements which may lead to a significant increase in low

frequency radiated noise

• transitions between track sections with differing support stiffness characteristics

• wheel and rail interface issues such as corrugation development

• access and inspection and maintenance of resilient components © State of NSW through Transport for NSW 2019 of 30



17. Provision for services Provision shall be made in the design and construction of track slabs for services as required

such as signalling, electrical and communications.

Services shall be positioned in accordance with the following requirements:

• ESC 215

• SPC 207 Track Monitoring Requirements for Undertrack Excavation

• T HR CI 12190 ST Service Installations within the Rail Corridor

• clear of any walking areas where they may present a trip hazard

• not interfere with, or obstruct, emergency walkways

• not obstruct access to, or reduce the capacity of, safe places

• not obstruct drainage

• not cast into the track slab

• not obstruct track control marks

The location of any services shall ensure that future access for maintenance of the services is

facilitated.

18. Documentation Appropriate and adequate information on design drawings and in technical reports that are

systematically stored enables ongoing informed decisions for future whole-of-life asset

management.

18.1. Drawings Engineering drawings shall comply with T MU MD 00006 ST Engineering Drawings and CAD

Requirements, and shall record or reference all information to ensure work can be constructed

and maintained, in accordance with the design.

The drawings shall identify design standards and construction specifications, and shall include

all project specific requirements necessary for completeness of the technical specifications.

Relevant references include applicable ASA standards, ASA drawings, ASA specifications,

RMS specifications, Australian standards and other relevant project specific specifications.

The design drawings and technical specifications shall at least account for and include the

following:

• safety in design

• quality processes © State of NSW through Transport for NSW 2019 of 30



• design criteria

• tolerances

• durability requirements

• construction methods

• site investigations (geotechnical and survey)

• site location and tracks (labelled with line and kilometrage marks)

• site survey (with railway boundaries)

• site plan (minimum scale of 1:200 with North point and Sydney shown on the left)

• track alignments and levels ('design' and 'existing' where applicable)

• drainage layout and details, including existing drainage

• materials

• testing requirements

• manufacturing requirements

• location and labels of structures, footings, natural features, trackside furniture and services

• track fixing details, including packing details where required

18.2. As-built drawings As-built construction drawings noting applicable variations to the approved design drawings

shall be prepared and submitted to the RIM at the completion of the construction works.

18.3. Reports A design report shall be prepared by the designer and submitted to the RIM. The report shall

include at least the following:

• site description and background, including existing infrastructure

• site location and track (line and kilometrage) and photographs

• design methodology and assumptions

• computer modelling and software utilised

• analysis results (both 'existing' and 'proposed')

• safety in design (including risk matrix)

• output from computer modelling

• drainage arrangement © State of NSW through Transport for NSW 2019 of 30



Where options are considered as part of a report, the report shall include the following:

• sketches illustrating each of the options

• guide cost for each option

• comparison of options (advantages and disadvantages)

• proposed maintenance plans

• recommendation with justification

19. Electrical requirements In electrified areas, the design of track slabs shall provide for earthing and bonding of metallic

components in order to mitigate touch potential hazards and corrosion of steel.

Track slabs shall be electrically isolated and have adequate clearances in accordance with the

design strategy specified in TN 016: 2015 Overbridges and footbridges – Earthing and bonding

requirements, and other requirements of the Lead Electrical Engineer, ASA.

20. Construction Track slab construction methods include ‘top-down’, ‘bottom-up’ or a combination of both.

Top-down construction comprises setting the rails in place with temporary supports then casting

the concrete track slab in-situ upto the underside of the rail baseplates.

Bottom-up construction involves construction of a track slab before attaching the rails.

Track slabs shall be constructed in accordance with SPC 301 (for example, concrete shall be in

accordance with QA specification B80 Concrete Work for Bridges). Substrate earthworks shall

be in accordance with QA specification R83 Concrete Pavement Base.

The design documentation shall reflect this requirement and shall include any project specific

requirements necessary for completeness of the technical specifications.

The finished surface of the track slab shall be constructed to a tolerance of +0 mm, -5 mm from

the design level.

The construction method shall ensure that rail baseplates are fully supported with no voids

forming in any grout layer used under the baseplates. Refer to T HR CI 12020 ST for further

requirements for direct fixed rail attachment.

The design of track slabs, including the refurbishment of existing, shall take into account

construction constraints, particularly under live rail operating conditions and track possessions.

Earthworks and excavation near structures shall comply with the requirements detailed in

T HR CI 12110 ST. The stability of excavations shall be maintained at all times.




Track drainage shall be integrated and constructed in accordance with SPC 310,

T HR CI 12030 ST and T HR CI 12130 MA Track Drainage.

The track on a track slab shall be constructed in accordance with SPC 206 Track Construction.

21. Maintenance The design of track slabs shall provide ease of access to components for inspection and

maintenance activities such as rail replacement, in-situ rail welding and emergency rail

clamping.

Maintenance requirements shall be specified, in the form of a technical maintenance plan, in the

design documentation of the structure. The requirements shall include examination tasks and

frequencies, damage limits and repair standards. In most cases, MN A 00100 Civil and Track

Technical Maintenance and ESC 302 Structures Defect Limits apply. However, it may be

necessary to document site-specific maintenance requirements.

The requirements and high-level processes for the development of technical maintenance plans

are detailed in T MU AM 01003 ST Development of Technical Maintenance Plans.

22. Decommissioning and disposal Decommissioning is the final process of withdrawing an asset from active service on the

network.

Disposal is the process of removing an asset from the network. For example, demolition of a

track slab followed by removal and recycling.

The decommissioning or disposal of an asset is the final stage of the asset life cycle. Proper

planning of this part of the life cycle is an integral part of the strategic life cycle process.

The process for the disposal of a track slab, usually undertaken in conjunction with a

replacement, shall include the following:

• justification (safety, financial, and so on) for disposal of the asset

• confirmation of stakeholder engagement regarding the proposed action; such engagement

shall include all relevant authorities, but not be limited to heritage, local, state and federal

government, the RIM and environmental body consultation

• agreement from all stakeholders to the decommissioning or disposal of the existing

underbridge

After decommissioning and disposal, the asset database shall be updated to reflect network

changes.

At least fifty per cent of construction and demolition waste by weight of the decommissioned

asset should be diverted from landfill.


t hr ci 12072 st track slabs - transport for nsw · a track slab is a reinforced concrete slab that...

Documents