Technical Note - TN 061: 2015
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www.asa.transport.nsw.gov.au
Technical Note - TN 061: 2015
Issued date:
06 October 2015
Effective date:
06 October 2015
Subject:
Withdrawal of ESC 240 Ballast and
SPC 241 Ballast
This technical note is issued by the Asset Standards Authority as a notification to remove from
use the following RailCorp documents:
•
ESC 240 Ballast, Version 2.4
•
SPC 241 Ballast, Version 2.3
ASA standard T HR TR 00192 ST Ballast, Version 1.0 supersedes these documents.
Authorisation:
Technical content
prepared by
Checked and
approved by
Interdisciplinary
coordination
checked by
Authorised for
release
Name
Melissa Melrose
David Cooper
John Paff
Graham Bradshaw
Position
Senior Engineer
Track Structure
A/Lead Track
Engineer
A/Chief Engineer Rail
Director Network
Standards and
Services
Signature
Date
© State of NSW through Transport for NSW
Page 1 of 1
ESC 240
BALLAST
Version 2.4
Issued April 2013
Owner:
Chief Engineer, Track
Approved
by:
Andrew Wilson
Technical Specialist
Wheel/Rail
Authorised
by:
Malcolm Kerr
Chief Engineer
Track
Disclaimer
This document was prepared for use on the RailCorp Network only.
RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be
sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the
copy of the document it is viewing is the current version of the document as in use by RailCorp.
RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes
any liability which arises in any manner by the use of this document.
Copyright
The information in this document is protected by Copyright and no part of this document may be reproduced, altered,
stored or transmitted by any person without the prior consent of RailCorp.
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Page 1 of 11
Engineering Standard
Superseded by T HR TR 00192 ST
Engineering Standard
Track
Superseded by T HR TR 00192 ST
RailCorp Engineering Standard — Track
Ballast
ESC 240
Document control
Version
1
Date
October 2006
2
October 2007
2.1
2.2
December 2009
August 2011
2.3
April 2012
2.4
April 2013
Summary of change
First issue as a RailCorp document. Includes content from
TS 3101, TS 3402, RTS.3430, CTN 04/09.
Revision of ramp requirements for change of formation level
below turnouts.
Format change only.
New section 4.2.8 - Moderating track stiffness. Addition of
guidelines for use of ballast mat on rigid support
Reformatted to new template; 4.2.4 - Explanation of
shoulder profile width added
Changes detailed in Summary table below.
Summary of changes from previous version
Summary of change
Control changes
Clarification of acceptance standard for maximum ballast depth
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Section
Document
Control
5.3
Page 2 of 11
Version 2.4
Superseded by T HR TR 00192 ST
RailCorp Engineering Standard — Track
Ballast
ESC 240
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
2.4
Definitions .................................................................................................................................4
3
Design & Performance Criteria..............................................................................................4
3.1
Track Configuration...................................................................................................................4
3.2
Ballast Design Criteria...............................................................................................................4
4
Approved Configurations.......................................................................................................5
4.1
Ballast Material and Grading.....................................................................................................5
4.2
Ballast Profile ............................................................................................................................6
5
Acceptance Standards .........................................................................................................10
5.1
Ballast Material and Grading...................................................................................................10
5.2
Crib and Shoulder Height........................................................................................................10
5.3
Ballast Depth...........................................................................................................................11
6
Damage Limits.......................................................................................................................11
6.1
Contamination .........................................................................................................................11
6.2
Strength/Stiffness....................................................................................................................11
6.3
Profile ......................................................................................................................................11
7
Repair standards...................................................................................................................11
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Version 2.4
Superseded by T HR TR 00192 ST
RailCorp Engineering Standard — Track
Ballast
1
ESC 240
Purpose, Scope and Application
This Standard establishes functional and design requirements, approved configurations,
acceptance standards, damage limits and repair standards for rail ballast.
It is applicable to all RailCorp main line and siding tracks and shall be applied to the
design of new trackwork, track renewal, reconditioning and ballast cleaning.
2
References
2.1
Australian and International Standards
AS 2758.7-1996: Aggregates and rock for engineering purposes Part 7: Railway Ballast
2.2
RailCorp Documents
ESC 200 - Track System
ESC 310 - Underbridges
SPC 241 - Ballast Specification
2.3
Other References
Nil
2.4
Definitions
Ballast
:
Nominal Size
:
Ballast is a free draining coarse aggregate or metallurgical slag
used to support railway tracks.
The designation of an aggregate which gives an indication of the
largest size particle present.
3
Design & Performance Criteria
3.1
Track Configuration
The configuration of track elements, including ballast, is specified in ESC 200 Track
System.
3.2
Ballast Design Criteria
The ballast material design and track cross-sectional ballast profile in this standard have
been developed in consideration of the following criteria:
Loading
• Service loads including effects of track alignment, maintenance standards, and
traffic task.
Materials
• Ballast consolidation requirements.
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RailCorp Engineering Standard — Track
Ballast
ESC 240
Interfaces with other rail infrastructure
• Sleeper material, type and spacing.
• Electrical properties in track circuited areas.
Support Requirements
• Required track modulus.
• Track support conditions and deflection criteria.
• Track formation material and condition.
Performance requirements
• The need to interlock sufficiently to provide resistance against excessive vertical,
lateral (buckling of the track) and longitudinal movement of sleepers and bearers.
• The need to reduce excessive loading and failure of the track formation.
• The need to provide adequate drainage of the track structure to the cess and allow
fines to migrate out.
• The need to be durable enough to resist crushing when subjected to the nominal
loadings
4
Approved Configurations
4.1
Ballast Material and Grading
Ballast grading shall be either "Standard" or "Fine" in accordance with the existing or
proposed track structure class detailed in RailCorp standard ESC 200 and as detailed in
Table 1.
For existing applications, detailed in ESC 200, all ballast shall meet the material and
grading requirements of RailCorp Specification SPC 241.
Alternative gradings (either as specified in AS 2758.7, or specifically designed) to meet
special requirements (eg special gradings necessary in conjunction with reduced ballast
depth) must be approved by the Chief Engineer Track.
Sieve
size
(mm)
63.0
53.0
37.5
26.5
19.0
13.2
9.50
4.75
2.36
Ballast Grade
Standard
Fine
Nominal size (mm)
60
50
(graded ballast)
(graded aggregate)
% passing by mass
100
–
85 – 100
100
50 – 70
70 – 100
20 – 35
–
10 – 20
40 – 60
2 – 10
–
0–5
20 – 30
0–2
10 – 20
–
5 - 10
Table 1 - Ballast grading
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RailCorp Engineering Standard — Track
Ballast
4.2
ESC 240
Ballast Profile
A typical track cross-section illustrating ballast profile is shown in Figure 1.
Ballast Shoulder Width
Sleeper
Ballast Shoulder
Height
Slope
1
Ballast
Formation
Ballast Depth
Figure 1 - Typical track cross-section and ballast profile
4.2.1
Shoulder Height
Ballast shoulder height (the distance from sleeper soffit to the under side of the rail) is
determined by the sleeper design. The ballast shall be profiled to the top of the end of
the sleepers. Depending on the sleeper design, the rail seat area may be higher than the
centre and ends.
4.2.2
Crib Height
The ballast shall be profiled to the top of the centre of the sleepers.
4.2.3
Shoulder Slope
For freestanding ballast, the slope of the ballast shoulder is assumed to be 1:1.5
(height: width).
4.2.4
Shoulder Width
The minimum shoulder distance is determined by the track stability requirements of rail
length. The requirements for current applications are detailed in Table 1.
Operating Class
Main line
CWR and LWR
Siding
CWR and LWR
Loose Rail
Design Ballast shoulder
width (mm)
Minimum
Maximum
400
700
400
300
700
700
Table 2 - Ballast Shoulder width
Ballast Shoulder width is measured from the extreme end of the sleeper, not the visible
end when the track is fully ballasted.
The ballast shoulder should extend horizontally from the sleeper end. It is, however,
acceptable for the ballast shoulder to be profiled in the plane of the sleeper for a normal
ballast shoulder width (nominally 400mm) to suit ballast regulators. Any extended
shoulders, such as on bridges, should be horizontal.
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Version 2.4
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RailCorp Engineering Standard — Track
Ballast
ESC 240
Design ballast shoulder width is one factor that contributes to overall track lateral stability.
Additional ballast shoulder width above the minimum and a ballast windrow up to rail
height outside the sleeper may be necessary in areas of poor track lateral stability to
provide adequate resistance to track buckling on sharp curves where design radius is
outside normal limits.
Location of
ballast windrow
Rail Level
Gauge
Face
Figure 2 - Location of ballast windrow
4.2.5
Ballast Depth
Ballast depth is the distance from the underside of the sleeper to the top of the finished
formation.
On superelevated track, the depth of ballast is measured from under the low rail.
Ballast depth shall be either "High" or "Medium" or "Low" in accordance with the existing
or proposed track structure class detailed in RailCorp standard ESC 200 and as detailed
in Table 3 and Table 4.
Category
High
Medium
Low
H
M
L
L(150)
L(100)
L(Nom)
Design Ballast
depth(mm)
Minimum
350
300
250
150
100
Nominal
Maximum
500
500
500
500
500
500
Table 3 - Ballast depth categories
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RailCorp Engineering Standard — Track
Ballast
ESC 240
New
Operating Class
Existing
Ballast
depth
Sleeper type
Main line
Passenger Main Line Medium duty concrete
Heavy duty concrete
Mixed Passenger
Medium duty concrete
Freight Main Line
Heavy duty concrete
Light Line
NA
Heavy Freight Option Heavy duty concrete
Sidings
(1)
General Yard
Medium duty concrete
Passenger
operations/ or
Medium duty concrete
maintenance
Passenger Siding
Timber
Engineering
Timber
Maintenance Siding
Ballast
depth
Sleeper type
(Note 3)
(Note 1, 2)
L
Timber
L
M
Timber
M
H
Timber
L
Heavy duty concrete H
L
Timber
L(150)
L
Timber
L(150)
L(100)
Timber
L(100)
L(Nom)
Timber
L(Nom)
Table 4 - Ballast height
Note: 1. Full ballast depth in existing track includes ballast that is not free draining
Free draining ballast may include ballast with fines such as sand, brake dust and
other fine material that does not restrict water flow.
2. Existing track may not necessarily achieve the target ballast depth.
3. Use of the design ballast depths with poor subgrades may still cause the
subgrade to be over stressed. Detailed investigation and analysis of the whole
track structure including the substructure condition may be necessary in these
problem situations. It can equally be demonstrated that in areas with very good
subgrades (natural or designed) it is possible to provide adequate support to the
track structure with lower ballast depths than those specified in Table 4. The
design ballast depth is based on the formation design model detailed in
Section 4.2.6.
Through turnouts the minimum ballast depth under turnout bearers is to be maintained by
lowering the formation level as required. The change in level of the formation is to be
ramped off as follows:
Turnout installation or replacement
where adjacent track is also being installed or
reconstructed
where major track reconstruction is not being
undertaken
4.2.6
Maximum grade
(relative to the track grade)
1 in 200
1 in 20
Formation Basic Design Model
The basic design model for ballast depth is based on the following formation strength.
• Top of formation - CBR >8
• Capping layer of 150mm thickness - CBR >50
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RailCorp Engineering Standard — Track
Ballast
ESC 240
H=500 to 1000mm
Base of excavation
Capping 150mm CBR>50,
Compaction 100% Standard
H=500 if insitu material CBR=3 to 8
H=1000 if insitu material CBR=1 to 3
Structural Fill CBR>8
Compacted to 100% Standard Compaction
Figure 3 - Track Formation - Basic Design Model
4.2.7
Alternative Ballast Profiles
The following alternative ballast profile designs may be adopted:
1. Ballast shoulder width may be reduced to a minimum of 75mm provided that:
– lateral restraint, such as a retaining wall, is provided. The additional lateral
restraint shall be at least equivalent to the restraint provided by the missing
shoulder ballast.
– arrangements are made for drainage of water from the formation.
2. Ballast shoulder width may be increased (eg for walkways or examination areas)
provided that alternative arrangements are made for drainage of water from the
formation.
3. Ballast depth may be reduced provided that
– measures are included to provide strength and durability at least equivalent to
the approved design
– measures are included to provide stiffness no less than the approved design
(e.g. use of special vibration isolation fastenings or a ballast mat).
4.2.8
Moderating Track Stiffness
The ballast profiles detailed above are suitable for standard track on earth foundations.
For track on rigid foundations such as ballast top bridges consideration shall be given to
moderating the track stiffness. Guidelines for use of ballast mat on rigid structures are
provided in Table 5. Special measures are required for transitioning between areas of
different stiffness such as bridge ends (see ESC 310). The design of the ballast mat
should also consider the bridge design requirements such as waterproofing (see
ESC 310).
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RailCorp Engineering Standard — Track
Ballast
Track
Category
(Note 1)
Sleeper
Type
High
(H)
Heavy duty
concrete
Medium
(M)
Heavy or
Medium
duty
concrete
Medium
duty
concrete
Low
(L)
ESC 240
Min Ballast Depth
(exc. mat)
Recommended Ballast Mat Stiffness
Range
> 300 and < 600 mm
250 -300 mm
< 250 mm but > 200 mm
> 250 and < 600 mm
Ballast mat (cstat = 0.15 N/mm3)
Ballast mat (cstat = 0.10 N/mm3)
(Note 2)
200 -250 mm
< 200 mm but > 150 mm
> 200 and < 600 mm
Ballast mat (cstat = 0.10 N/mm3)
(Note 2)
150 -200 mm
< 150 mm but > 100 mm
Ballast mat (cstat = 0.10 N/mm3)
Ballast mat (cstat = 0.15 N/mm3)
Ballast mat (cstat = 0.10 N/mm3)
Ballast mat (cstat = 0.15 N/mm3)
Ballast mat (cstat = 0.10 N/mm3)
(Note 2)
Ballast mat (cstat = 0.10 N/mm3)
Table 5 - Guideline for Ballast Mat Usage on Stiff Structures (Bridge/Tunnel)
Note: 1. Operating Class: Main Line – refer to Table 4 for definition of Track Category
2. Should consider case by case
5
Acceptance Standards
All work involving the laying of ballast as part of new track installation or track renewal
shall meet the following acceptance requirements:
5.1
Ballast Material and Grading
Supplied (new) ballast shall meet an approved design (SPC 241 or equivalent approved
by the Chief Engineer Track).
5.2
Crib and Shoulder Height
The ballast shall be profiled to the top of the centre and end of the sleepers.
5.2.1
Ballast Shoulder Width
Operating Class
Main line
CWR and LWR
Siding
CWR and LWR
Loose Rail
Ballast shoulder width
(mm)
Acceptance
Minimum
Maximum
390
700
390
290
700
700
Table 6 - Ballast shoulder width acceptance limits
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RailCorp Engineering Standard — Track
Ballast
5.3
ESC 240
Ballast Depth
Category
High
Medium
Low
H
M
L
L(150)
L(100)
L(Nom)
Ballast depth(mm)
Acceptance
Minimum
Free
Minimum
Maximum
(Note 1)
Draining
325
NA
200
275
NA
75
225
NA
75
125
NA
75
100
NA
NA
NA
NA
NA
Table 7 - Ballast Depth acceptance limits
Note 1:
Where large ballast depths are used consideration must be given to the implications for
lateral and vertical stability.
6
Damage Limits
6.1
Contamination
Ballast shall be considered to have failed to meet functional requirements when the
Fouling Index >40.
The Fouling Index (FI) = P(4) + P(200)
Where
6.2
o
P(4) =
P(200) =
Percentage passing 4.75 mm (N 4) sieve
o
Percentage passing 0.075 mm (N 200) sieve.
Strength/Stiffness
To be determined
6.3
Profile
To be determined
7
Repair standards
Recycled ballast
• must be cleaned to remove fines and contaminants, AND
• must meet an approved design (SPC 241 or equivalent approved by the Chief
Engineer Track), OR
• must have reinforcement designed to provide strength and durability at least
equivalent to the approved design, OR
• must ONLY be used below the depth specified for free draining ballast.
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