RMS BTD List.pdf

File: SF2013/080714
ROADS AND MARITIME SERVICES BRIDGE
TECHNICAL DIRECTION MANUAL
1. INTRODUCTION
1.1 Purpose
The purpose of the Roads and Maritime Services (Roads and Maritime) Bridge
Technical Direction Manual is to provide a broad based set of Roads and Maritime
policies and guidelines on technical issues related to bridgeworks. By complying with
the Manual, any planning and design of new bridges, as well as rehabilitation,
maintenance and/or widening of existing bridges, carried out for Roads and Maritime
will have consistency in terms of quality, aesthetics or efficient use of resources, as
required by Bridge Engineering, Roads and Maritime Services.
1.2 Scope
This Manual sets Roads and Maritime policy and provides guidelines on bridge related
technical issues for all new, rehabilitation and other designs and related matters for
Roads and Maritime funded bridges and those that will become property of the Roads
and Maritime. It does not contain any comprehensive detailed design procedures.
1.3 Who is it for
This Manual is designed for use by all personnel carrying out work for Roads and
Maritime bridges, or for bridges that will become property of Roads and Maritime, who
are responsible for either design or administering design as well as documentation
and construction of new bridges and rehabilitation, maintenance or widening of
existing bridges.
1.4 What it contains
This Manual contains a collection of all current Bridge Technical Directions including
still current Bridge Policy Circulars, Chief Bridge Engineer Circulars and Bridge Design
Instructions issued to date. The associated Register specifies which current Bridge
Technical Directions and Circulars comprise the Roads and Maritime Services Bridge
Technical Direction Manual.
1.5 Amendments to the Manual
All new Bridge Technical Directions and revisions arising from changes in technology,
knowledge or process to any existing Bridge Technical Direction or Circular, together
with the updated Register, are issued to maintain currency of the Manual.
1.6 Contact Details
For further information regarding the Bridge Technical Direction Manual, please
contact:
Senior Bridge Engineer (Special Projects)
Bridge Engineering
Roads and Maritime Services
Octagon Building 5F
110 George Street
Parramatta NSW 2150
Tel: 02 8837 0805
Fax: 02 8837 0054
OTB-TP-504-F03 Issue 2014/04 (19 December 2014) Page 1 of 5

2. REGISTER OF CURRENT BRIDGE TECHNICAL DIRECTIONS
The following bridge technical directions constitute the Roads and Maritime Services
Bridge Technical Direction Manual. These bridge technical directions are available on the
Internet and Roads and Maritime Intranet.
No. Subject
Date of
Approval
BTD
2014/03
Rev1
Release of Secure Bridge Plans
13/8/2014
19/12/2014
BTD 2014/02 Durability Plan for Bridgeworks and Other Structures 31/3/2014
BTD 2014/01 Traffic Loading for Bridges 7/02/2014
BTD 2013/01 Design of Precast Reinforced Concrete Box Culverts 26/03/2013
BTD 2012/01 Provision of Safety Screens on Bridges 12/07/2012
BTD 2011/08 Testing of Cast-in-Place Concrete Piles 25/10/2011
BTD 2011/07 RMS(RTA) Interim Code For Concrete Design 3/05/2011
BTD 2011/06 Provisions for the Design of Super-T Girder Bridges 4/04/2011
BTD 2011/05 Minimum Restraint Capacity for Superstructures 25/03/2011
BTD 2011/04 Re-Issue of Standard Bridge Drawings 25/03/2011
BTD 2011/03 Skid-Resistant Treatments for Bridge Deck Joints 25/03/2011
BTD 2011/02 Use of CFA Piles on Bridges 25/03/2011
BTD 2011/01
Use of Proprietary Precast Reinforced Concrete Modular Bridge
Deck Systems
18/03/2011
BTD 2010/04
Issue of New Standard Bridge Drawing No RMS(RTA)B100 –
Design and Construction and Alliance Team Project Drawing
Sheet
14/10/2010
BTD 2010/03
Pretensioned Bridge Members – Concrete Transfer Strength
Requirements
8/10/2010
BTD 2010/02 Timber Bridge Design – Adoption of AS 1720.1-2010 20/09/2010
BTD 2009/02 Management of Bridge Rehabilitation Design Projects 14/07/2009
BTD
2009/01
Rev1
Design of Sign Structures
22/06/2009
26/03/2010
BTD 2008/17
Changes to Standard Bridge Drawings - RC Link Slab for Super T
Girder Decks
12/09/2008
BTD 2008/16 Timber Bridge Manual 30/06/2008
BTD 2008/15 Concrete Parapets on Pedestrian Overbridges 6/06/2008
BTD 2008/14
Changes to Standard Bridge Drawings– Spaced Planks Standard
Drawings
26/05/2008
BTD 2008/13
Provisions for Future Cathodic Protection of Reinforced Concrete
Bridges
16/07/2008
BTD 2008/12 Provisions for Concrete Structures in Acid Sulfate Soils 14/05/2008
BTD 2008/11 Lists of RMS(RTA) Approved Bridge Components and Systems 5/05/2008
BTD 2008/10 Bridge Deck Joints 5/05/2008
BTD 2008/09 Link Slabs for Precast Pretensioned Concrete Girder Bridges 25/02/2008

No. Subject
Date of
Approval
BTD 2008/08 Provision of Conduits in Bridge Traffic Barriers 25/02/2008
BTD 2008/07 Design of Bridge Supports for Collision Load from Road Traffic 25/02/2008
BTD 2008/06 Joints in Precast Concrete Barrier Elements on a Grade 25/02/2008
BTD 2008/05 Splicing of Steel Girders Using Bolts 25/02/2008
BTD 2008/03 Use of Profiled Steel Sheeting in Bridges and Minor Structures 25/02/2008
BTD 2008/02
Access for Inspection, Monitoring and Repair or Replacement of
Bridge Components
18/02/2008
BTD 2008/01
Changes to Standard Bridge Drawings – Bridge Traffic Barrier
Termination Details
7/02/2008
BTD 2007/13 Durability of Steel Piles in Contact with Acid Sulfate Soils 17/12/2007
BTD 2007/12 Design for Replacement of Bridge Bearings 17/12/2007
BTD 2007/11
Horizontal Reinforcement for Crack Control in Walls and Wall
Type Piers
17/12/2007
BTD 2007/10 Restraint of Longitudinal Reinforcement in Columns 17/12/2007
BTD 2007/09 Soil-Arch Structures 17/12/2007
BTD
2007/08
Rev1
Design of Replacement Traffic Barriers on Existing Bridges
27/09/2007
18/11/2009
BPC 2007/07 Vertical Clearances on Bridges 6/08/2007
BPC 2007/06 RMS(RTA) Structural Drafting and Detailing Manual 9/07/2007
BPC 2007/05 Design of Integral Bridges 1/08/2007
BPC 2007/04
Changes to Standard Bridge Drawings – Steel Traffic Barrier
Railing Joints
6/07/2007
BPC 2007/03
Changes to Standard Bridge Drawings – Quarterly Update –
Revised Australian Standards
21/06/2007
BPC 2007/02
Changes to Standard Bridge Drawings – Installation of
Elastomeric Bearings for PSC Girders
5/04/2007
BPC 2007/01
Changes to Standard Bridge Drawings - Revision of Standard
Bridge Drawings
19/01/2007
BPC 2006/13
Changes to Standard Bridge Drawings – Revision of Three
Standard Bridge Drawings – Nos RMS(RTA)B032;
RMS(RTA)B041; RMS(RTA)B042C
27/10/2006
BPC 2006/09
Changes to Standard Bridge Drawings – Reinforcement
Nomenclature Changed on All Bridge Standard Drawings
Containing Reinforcement
20/10/2006
BPC 2006/07
Changes to Standard Bridge Drawings – Revision of Standard
Bridge Drawing No RMS(RTA)B029 – Standard Notes
3/07/2006
BPC 2006/05 Pipes and Conduits for Bridgeworks 24/05/2006
BPC 2006/04
Changes to Standard Bridge Drawings – Bridge Traffic Barriers –
Standard Cross Sections
3/07/2006
BPC 2006/03 RMS(RTA) Approval of Proprietary Bridging Systems 24/05/2006
BPC 2005/10 Reissue of Standard Bridge Drawings 16/12/2005
BPC 2005/09 Provision of Disabled Access for Pedestrian Bridges 11/11/2005
BPC 2005/08 Welding of Bridges 18/11/2005
BPC 2005/06 Bird Nesting in Bridge Abutments & Box Girders 3/11/2005

No. Subject
Date of
Approval
BPC 2005/05
Use of Steel Fibre Reinforced Reactive Powder Concrete
(‘Ductal’) in RMS(RTA) Works
8/09/2005
BPC
2005/04
Rev1
Pot Bearing Attachment Plates
24/10/2005
18/11/2009
BPC 2005/03
Installation of Elastomeric Bearings for Pretensioned Concrete
Girders - Standard Drawings
6/05/2005
BPC 2004/11
Strategies for Enhancing the Durability of Post-Tensioned
Concrete Bridges
30/11/2004
BPC 2004/10 Bridge Approach Slabs - Standard Drawings 6/12/2004
BPC 2004/09 Policy Circulars Made Redundant by AS 5100:2004 16/09/2004
BPC 2004/08
Inspection of Modular Bridge Expansion Joints and Control of
Noise
16/09/2004
BPC 2003/08 Bridge Screens 9/12/2003
BPC 2003/07 Bridge Maintenance Piling Works 9/12/2003
BPC 2003/06 Timber Truss Cross Girder Replacements 9/12/2003
BPC 2003/04
Use of Proprietary Expanded Metal Construction Joints and Shear
Keys
15/02/2003
BPC 2003/03 Bituminous Surfacings for Timber Bridge Decks 15/02/2003
BPC 2003/02 Waterproofing Membranes for Concrete Bridge Decks 19/02/2003
BPC 2002/05 Bridge Concept 21/03/2002
BPC 2002/03
Standard Connector – Thrie-Beam to Old Three Rail RHS Traffic
Barrier
1/03/2002
BPC 2002/02 Maximum Concrete Strengths for Use in RMS(RTA) Works 1/03/2002
BPC 2001/01 Replacement of Chief Bridge Engineer’s Circulars 15/08/2001
CBE 2000/09 Geotechnical Information for Bridges 19/05/2000
CBE 2000/08 Bar Shapes and Steel Lists for Precast Concrete Members 19/05/2000
CBE 2000/05 Compaction of Concrete in Solid and Non-circular Bridge Columns 11/05/2000
CBE 1999/15
Timber/Concrete Composite Bridge Modules Test Loading of
Module - Design Criteria
26/11/1999
CBE 1998/15
Multi Span Plank Bridges with Link Slabs Guidelines for Bearing
Selection
26/08/1998
CBE 1998/12 Tech CulvertTM
23/07/1998
CBE 1998/08 Bridge Bearings - Design for Maintenance or Replacement 26/05/1998
CBE 1997/10 Use of Brand Names 20/08/1997
CBE 1997/05 Design of Bearings for Durability 2/06/1997
CBE 1997/01 Variability of Concrete Properties 9/04/1997
CBE 1996/05
Registration and Standard of Bridge Designs and Drawings for
Bridge Works Funded by the Authority on Main Roads
29/02/1996
CBE 1996/04 Driven Piles 17/06/1996
CBE 1995/03 Information to be Shown on Drawings for Driven Piles 23/10/1995
CBE 1995/02 Stress Laminated Timber Bridges 25/01/1996
CBE 1994/07 Mass of Girders 16/06/1994

No. Subject
Date of
Approval
CBE 1994/05 Drainage of Voids in Bridge Deck 26/08/1994
CBE 1993/03 Socket Inserts for Precast Concrete Girders 25/02/1993
CBE 1991/11
Bridges over Roads. Horizontal Clearances and Visual
Perceptions
28/10/1991
CBE 1991/06 Permanently Cased Piles - Driving Shoe Details 10/07/1991
CBE 1990/10 Reinforcement Detailing 27/06/1990
CBE 1990/09 Weld Category - Fabricated Steelwork 1/06/1990
CBE 1990/07 Cast-in Angle Details - Amendments to Sketch Number 89-D-1 29/03/1990
CBE 1989/10 Detailing Steel Members 22/08/1989
CBE 1988/08 Provision of Curtain Walls 27/07/1988
BDI 1986/02 Design for Continuous Superstructures 21/04/1986
BDI 1985/07 Anchor Bolts 20/09/1985
BDI 1985/06 Bent on Site Reinforcing Bars 5/09/1985
BDI 1984/06 Provision of Drainage on Bridge Kerb 22/10/1984
BDI 1980/11 Provision of Lifting Lugs on Steel Girders 4/06/1980
BDI 1980/03 Bearing Levels 25/01/1980
The following link goes to the register that contains details of all Bridge Technical
Directions published to date, including withdrawn and superseded BTDs, for use by
Roads and Maritime staff. External parties will not be able to access this register:
http://home.rta.nsw.gov.au/policiesanddocuments/documentsites/ops/technical_services_bridge_proc
edures/docs/otb-tp-504-f01.xls

Technical Direction
BRIDGE
BTD 2014/03 REV 1
Release of Secure Bridge Plans
Summary: Audience:
This technical direction deals with the release of secure bridge plans
from the corporate records keeping system, and outlines the
requirements for the treatment of such plans, once approved for
release.
 RMS Personnel
 Consultants
 Contractors
Background
Certain secure bridge plans in the Roads and Maritime Services corporate records keeping system require
approval prior to their release to Roads and Maritime Personnel, Consultants and Contractors.
Until recently, approval for the release of these drawings was issued by the Manager of the Strategic
Infrastructure Group. As a result of the recent disbanding of this group, a new approval process for the
release of such plans is now required
Information
This Technical Direction specifies the new approvals process for the release of secure bridge plans.
Secure plans for bridges on the M5 East and Private Motorways are not covered by this Technical
Direction.
Bridge Technical Direction
Approval for the release of secure bridge plans to Roads and Maritime Personnel, Consultants and
Contractors may only be issued by the General Manager Critical Infrastructure and Security (GMCIS) or
the Principal Engineer Bridges (PEB).
All approvals to release secure bridge drawings must be issued in writing. Where any request for access is
rejected, the other authorising officer/s and the applicant shall be informed of the outcome in writing.
Any approval to access secure bridge plans is subject to the following conditions:
1. Drawings are kept confidential during the stated purpose;
2. Plans are to be destroyed in a secure manner after the completion of the task and;
3. For personnel not assigned to Roads and Maritime Services:
a) Before approval for release of secure drawings is sought, security clearance of the person/s
using the drawings shall be obtained from the Manager Sydney Harbour Bridge and;
b) Before access to secure bridge plans is provided, a ‘Confidentiality Deed Poll’ is signed.
Approvals:
Owner: Wije Ariyaratne
Principal Engineer Bridges
Review Date:
Authorised by: Chris Harrison
Chief Engineer
Effective
Date:
19/12/2014
Printed copies of this document are uncontrolled Page 1 | 2

Release of Secure Bridge Plans | BTD 2014/03 Rev 1
The GMCIS and the PEB may delegate approval to release secure plans on their behalf, for fixed time
periods. Such delegation must be stipulated in writing and is not transferable.
The General Manager, Contract Management Office; Manager Bridge and Maritime Assets; Strategic
Infrastructure Manager and Bridge Maintenance Planners (within their respective regions), are exempt from
the requirements of this Technical Direction and shall have access to secure bridge plans, when
necessary.
Printed copies of this document are uncontrolled Page 2 | 2

Technical Direction
BRIDGE
BTD 2014/02 Reference Nil
Durability Plan for Bridges and Other
Structures
Durability Plan for Bridges and Other
Structures
Summary: Audience:
This Technical Direction deals with preparation of durability plans for
bridge and other structures for major projects and requires their
preparation be in consistent formats in accordance with RMS’s
“Guide for the Preparation of a Durability Plan”.
• Designers
• Project Managers
• Contract Administrators
• Asset Managers, Bridge Maintenance Planners
• Publication on RMS’s Intranet and the Internet
Background
Over the past 15 years, project teams have provided durability plans where required by the project
Scope of Work and Technical Criteria (SWTC). The plans have often been voluminous, of variable
quality or in inconsistent formats. This has resulted in plans that are difficult to review and apply.
Information
RMS has recently prepared a “Guide for the Preparation of a Durability Plan”. The guide provides means
to appropriately assess the durability of the works. It outlines the information, measures and formats
required for durability plans for such projects that can be effectively applied during the design,
construction and maintenance of works.
Durability plans prepared for RMS projects shall be in accordance with the “Guide for the Preparation of
a Durability Plan”. The guide can be found at:
http://www.rms.nsw.gov.au/doingbusinesswithus/downloads/lgr/guidefordurabilityplan.pdf
Approvals:
Owner: Senior Bridge Engineer (Policy, Specifications and
Durability)
Review
Date:
Authorised by: Wije Ariyaratne
Principal Engineer, Bridge and Structures
Date: 31/03/2014 Page 1 | 1
Printed copies of this document are uncontrolled.

Contact: M Bennett
Section: Bridge and Structural Engineering
Telephone no: 8837 0802
File no: 94M3917
Circular Number: BTD2014/01
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Corporate Circular
CC: BTD2014/01
BRIDGE TECHNICAL DIRECTION BTD2014/01
TRAFFIC LOADING FOR BRIDGES
Background
AS 5100 Bridge Design was adopted for the design of bridges and related structures on the
classified road network in NSW on 7 May 2004.
AS 5100 defines a design traffic loading model designated as SM1600. The SM1600 traffic
loading does not correspond to any specific truck configurations, but it does account for the
possibility of two multi-trailer trucks travelling in convoy in a traffic lane.
Unlike some previous Australian bridge design codes the traffic loading model does not
make provision for reduced traffic loadings for minor roads with low traffic volumes.
However, it is recognised that in some limited circumstances, a lighter traffic loading could be
appropriate for the design of the structure. This BTD defines the conditions where reduced
traffic loading may be permitted and prescribes the minimum traffic loading that could be
adopted for the design of bridges on minor roads.
Information
The SM1600 traffic loading was developed in response to increasing legal truck mass and
truck axle loads, and new configurations of heavy vehicles to ensure that over the design life
of bridges the actual traffic loads will not exceed the design loads. The traffic load factor of
1.8 in the ultimate limit state was derived from statistical records of measured axle loads to
account for the likelihood of over-loaded vehicles on the road network.
It is recognised that, under certain conditions, a reduced traffic loading may be appropriate
for structures on minor local roads.
This Bridge Technical Direction replaces BPC 2004/06 which is now withdrawn.
• Bridges on or over classified roads may be designed for a lesser traffic loading than
SM1600 provided that all of the following criteria are satisfied:
a. The bridge will provide access to either a limited number of private properties,
crown land, state and national park or state forest or a combination of these
where the likelihood of land use change is low, because physical; landscape or
planning constraints would make future development difficult.;

Contact: M Bennett
File no: 94M3917
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b. The route alignment is unsuitable for B-doubles or other multi-trailer heavy
vehicles, and is unlikely within the design life of the structure to be improved to a
sufficient standard to allow travel by such vehicles;
c. The number of heavy vehicle movements is predicted not to exceed 150 AADT
within 30 years;
d. The maximum span of the bridge is 25 m; and
e. Either the superstructure of the bridge consists of simply supported spans ( i.e.
not structurally continuous), or the superstructure is continuous and the
application of SM1600 traffic loading would not cause a load reversal in any of the
members of the structure at the ultimate limit state or uplift at the supports at the
serviceability limit state
• The approval of the Principal Engineer, Bridge and Structures shall be obtained prior to
the adoption of a reduced traffic loading.
• Irrespective of the traffic loading to be adopted for design of new bridges, their traffic
barrier performance requirements and design shall be in accordance with the AS 5100.
• The minimum reduced traffic loading (including centrifugal and braking forces) for bridges
on the road network shall be the W7, T44 and L44 traffic loadings with corresponding
load factors, multiple lane modification factors and Dynamic Load Allowance as specified
in the 1992 Austroads Bridge Design Code and as detailed in Part 7 of AS 5100. For
fatigue loading the number of stress cycles for a Functional Class 1 road, as defined in
1992 Austroads Bridge Design Code shall apply.
Classified road has the same meaning as contained in the Roads Act 1993, namely “any of
the following:
(a) a main road,
(b) a highway,
(c) a freeway,
(d) a controlled access road,
(e) a secondary road,
(f) a tourist road,
(g) a tollway,
(h) a transitway,
(i) a State work”
References: BPC 2004/06
Effective date: 7/02/2014
Approved: Wije Ariyaratne
Principal Engineer, Bridge and Structures
DISTRIBUTION:
Publication on RMS’ Intranet and the Internet
The circulation list for the Bridge Technical Direction Manual
All Bridge Engineering Staff and Skill-Hire Contractors
Asset Managers, Bridge Maintenance Planners and Support Officers
Manager, Project Management Office

Contact: Mark Bennett
File no: 94M3917
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Corporate Circular
CC: BTD2013/01
DESIGN OF PRECAST REINFORCED CONCRETE BOX CULVERTS
Background
This Bridge Technical Direction stipulates Roads and Maritime Services (RMS) required design and
construction practice for precast reinforced concrete box culverts (RCBC).
Information
Major problems with differential settlement and damage by floods have been experienced with culverts
without cast-in-situ base slabs and precast wingwalls for high crown units.
This Bridge Technical Direction supersedes BTD/2008/04_Rev1, which is now withdrawn.
As specified in RMS R16, RCBC for RMS shall be designed in accordance with AS 1597.2 and AS 5100
for a design life of 100 years.
For all RCBC designed and constructed for RMS or those that will become property of RMS, the
following conditions shall apply:
a. Base slabs shall be cast-in-situ reinforced concrete;
b. Base slab of single cell culverts, shall extend a minimum of 300 mm beyond the outer faces of the
inverted U-shaped precast crown units. For multi-cell culverts, the base slabs shall extend a
minimum of 300 mm beyond the outer faces of the outer units;
c. Dowels in base slab expansion or contraction joints or dowels connecting precast link slabs with
precast crown units shall be stainless steel Grade 304 to ASTM A276. The dowels shall be designed
for the shear forces across the joint and shall have a minimum diameter of 20 mm;
d. Dowels in base slabs shall be at least 600 mm long, at a maximum spacing of 600 mm and
debonded on one side of the joint;
e. Contraction joints in base slabs shall coincide with butt joints between crown units;
f. At least two dowels shall be provided at each end of the slab, in link slab to crown unit connections,
g. Wingwalls and headwalls shall be cast-in-situ, where the nominal height of the end crown unit is
1800 mm or greater;

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h. Cast-in-situ reinforced concrete slabs shall be provided over crown units, where the minimum
pavement depth over the top of the crown units cannot be achieved;
i. Cut-off walls shall be provided at the ends of the base slab and on the front faces of adjacent
wingwalls;
j. The assumed dimensions, or the actual dimensions where available, of the precast crown units shall
be shown on the design drawings;
k. Crown units shall be placed on mortar in recesses in base slabs to ensure even bearing and restraint
of the base of the legs. The reduced cover in the base slab under the recess is deemed to comply
with Clause 4.10 of the AS 5100.5 where the following requirements are met:
• The nominal cover under the recess is 30 mm; and
• A non-shrink cementitious mortar with minimum 28 day strength of 40 MPa is specified to fill
the recess.
The depth of the recess shall not be less than:
• 25 mm; and
• the nominal cover for the relevant exposure classification specified in Clause 4.10 of AS 5100.5
minus 30 mm.
Example: For exposure classification C and for 50 MPa concrete the appropriate nominal cover is
70 mm. The depth of the recess must be not less than 70 mm – 30 mm = 40 mm.
References: BTD2008/04_Rev1
Effective date: 26 March 2013
Principal Bridge and Structures Engineer
DISTRIBUTION:
Publication on RMS’s Intranet and the Internet
Manager Information Management Systems
Manager, Road Asset Policy and Strategy

Corporate Circular
CC: BTD2012/01
PROVISION OF SAFETY SCREENS ON BRIDGES
Background
Roads and Maritime Services recognises that there is a risk to motorists from objects being dropped or
thrown from overbridges onto traffic passing underneath. Generally these incidents are infrequent and
sporadic. However, severe injuries and fatalities have occurred in the past.
Technical Direction TD2002/RS02 was issued in October 2002 to provide a risk assessment procedure
for the evaluation of the need for screens on existing and new bridges and to set guidelines for the
design of the safety (protection) screens.
This Bridge Technical Direction updates and replaces TD2002/RS02.
Objectives
The objectives of this Technical Direction are to:
1. Establish the criteria to determine the need to provide safety screens on new bridges and to
retrofit safety screens on existing bridges
2. Provide guidance and standards for the design of safety screens that satisfy structural design,
road safety, traffic operation and urban design objectives.
3. Outline alternative and additional measures that can be taken to reduce risk of objects being
dropped or thrown from bridges.
This Technical Direction does not cover methods for the prevention of objects being thrown from the
side of the road, a cutting or an embankment.
Risk Parameters
The risk of serious injury associated with these incidents is mainly dependent on the height of the bridge
above the road beneath and the speed of the vehicle that may be hit by the object.
For passenger cars, an increase in speed from 80 km/h to 100 km/h will have a greater influence on the
outcome than doubling the bridge height from 6 to 12 metres. For trucks, with a windscreen angle
generally much closer to the vertical, the influence of bridge height is negligible compared with travel
speed. It should be noted that this analysis only approximates the injury risk, as there are many other
factors that will influence the outcome, including the size and strength of the windscreen, the size, shape
and composition of the object being dropped.
Object dropped from high bridges have the potential to cause severe impacts. However, it is more
difficult for perpetrators to target individual vehicles accurately.
Contact: M V Bennett
Section: New Design, Bridge and Structural Engineering
Telephone no: 02 8837 0802
File no: 94M3917
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Accordingly, the speed of traffic on the road beneath the bridge is the most important factor in
determining priorities. It is anticipated that bridges over rural roads where the posted speed limit is less
than 80 km/h and for urban roads where the posted speed limit is less than 60 km/h would only be
screened in exceptional circumstances.
Assessment Criteria
Assessment for the need for safety screens on bridges over roads shall be carried out using the formal
risk assessment process set out in Appendix 2.
The risk assessment factors to be considered and scored are as follows:
• Previous history of incidents and/or signs of graffiti in the vicinity of the bridge
• Ease of pedestrian access
• Type of road underneath
• Posted speed of the road underneath
• Proximity to pedestrian traffic generators such as schools, hotels, clubs, sporting venues etc
• Lighting
• Visibility of pedestrians on the bridge to traffic on the bridge and to traffic passing under the
bridge
• Amount of loose material nearby
The theoretical maximum score using the matrix rating system is 68. A score greater than or equal to 30
warrants action.
For new bridges a previous history of incidents in the local area may not be available. In these cases, the
experience at similar sites should be taken into account. Where it is anticipated that during the life of the
structure a future risk assessment would require their installation, safety screens should be fitted when
the bridge is constructed. The installation of safety screens should not be delayed until a serious incident
definitely establishes the need.
For existing bridges the risk assessment score should be reviewed if the conditions at the bridge site
change.
Safety screens shall be provided on all pedestrian, shared path, cycleway and road bridges with footways
over railway lines. For road bridges without footways the Railway Authority shall be consulted to
determine the need for safety screens. The design and extent of these safety screens shall be as required
by the relevant Railway Authority.
Design Standards
Safety screens shall be designed to have a minimum design life of 50 years. They shall be designed to
comply with the requirements set out in Appendix 1.
On existing bridges, screens would normally be retrofitted as separate structural elements independent
from the existing pedestrian or traffic barriers.
On new pedestrian, cycleway, shared path or road bridges with footways the screens should be designed
as an integrated part of the pedestrian or cycleway barrier systems. On new road bridges the safety
screen should be designed with a post spacing and appearance complimentary to the traffic barrier.

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Noise walls and privacy screens fitted to bridges, provided they comply with the height requirements of
Appendix 1 may also function as safety screens.
Safety screens shall be designed to minimise future maintenance costs and to minimise the risk of damage
due to vandalism and graffiti.
Alternative and Additional Measures
If the risk assessment score is marginal and the decision is made not to install safety screens other risk
reduction methods should be considered including:
• Removal of loose stones, litter and sundry foreign objects in the vicinity of the bridge that could
potentially be used as missiles
• Replacement of timber and metal delineator posts in the immediate vicinity of the structures
with lightweight plastic alternatives
• Modification or removal of other road furniture that could be used as projectiles
• Installation of lighting or enhanced lighting
• Raising awareness of the danger of dropping or throwing objects from overbridges with school
and community groups and local authorities
• Camera surveillance
Records Management
The installation of safety screen on a bridge shall be recorded in the Bridge Information System (BIS).
Attachments to this Technical Direction
1. Appendix 1 - Design of safety screens on bridges
2. Appendix 2 - Risk assessment matrix
Effective date: 12 July 2012
Principal Bridge and Structures Engineer
DISTRIBUTION:
Publication on RMS’ Intranet and the Internet
Corporate Documentation Registrar
Manager, Road Information and Asset Management Technology

File no: 94M3917
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Appendix 1 - Design of Safety Screens on Bridges
Geometric Requirements
Safety screens shall have the following geometrical properties:
(a) A minimum height of 3.0 m above the roadway or footway surface or 2.0 m above the top rail
or top surface of any adjacent pedestrian or traffic barrier, whichever is the greater.
(b) The safety screen shall extend at least 6 m beyond the edge lane line of the roadway below or,
if this is not possible, to within 1 m of the end of the Abutment wing walls or on pedestrian and
shared path bridges to the landings at the end of the main bridge spans.
The safety screen shall be at or above the minimum height for a distance of at least 2 m past the
outer edge lane line of the roadway below, and may then taper down in height.
(c) Where the safety screen is adjacent to the traffic carriageway, the screen shall have a minimum
setback from the inside face of the traffic barrier of 350 mm.
(d) For pedestrian footways on road bridges and on pedestrian bridges the safety screens shall have
a minimum head clearance of 2.20 m at the inside face of the railing and 2.40 m at 150 mm
from the inside face of the railing or handrail.
(e) On shared path bridges and cycleways the safety screens shall have a minimum head clearance
of 2.5 m at 300 mm from the inside face of the adjacent railing or handrail.
(f) A minimum clear width of 80 mm shall be provided between the safety screen and the railing or
handrail.
(g) Post spacing shall not exceed 3 m. However, as the standard size of a mesh panel is
2.4 x 3.0 m, post spacing based on an infill panel width of 2.4 m will eliminate the need for a 2
mesh panels vertically.
(h) Pedestrian and shared path bridges with a clear width between railings or handrails of up to
3.0 m may be fully enclosed, but measures shall be taken to restrict unauthorised access onto
the top of the screen. On shared path bridges the minimum head clearance over the central
2.0 m of the bridge carriageway shall be 3.0 m.
(i) For safety screens that are not fully enclosed, the maximum effective outward slope measured
to a straight line drawn through the top of the infill panel and the bottom of the infill panel at
the top of the parapet or kerb shall not exceed 1 in 10.
(j) Posts for safety screens that are located on a bridge where the longitudinal grade of the bridge
exceeds 6% at any point, shall be detailed to be truly vertical for the full extent of the screens.
Where the longitudinal grade does not exceed 6% at any point, the posts should normally be
perpendicular to the top of the concrete parapet or footway surface.
Construction Details
The following construction details shall be adopted for the design of the safety screens:
(a) The design of the safety screen should be modular, so that individual components can be easily
replaced if damaged by an over-width or errant vehicle.
(b) It is preferred that safety screens are attached to the top or outside face of the bridge parapets.
However, safety screen posts may be bolted to the posts or base plates of traffic barrier railings,
provided the minimum lateral clearance requirements are met.
(c) Safety screens shall not be attached to the railings of traffic barriers.
Infill Panels
For normal road bridges the safety screens should use wire mesh panels. However, in special
circumstances such as heritage bridges, where the safety screens also have a noise mitigation function,

File no: 94M3917
5 of 7
bridges fitted with advertising signs or bridges that require special architectural treatment the use of
alternative panel types may be approved by the Principal Bridge and Structures Engineer.
On pedestrian and shared path bridges, to meet urban design and functional objectives, a range of infill
panel types is permitted including wire mesh, perforated metal, profiled or punched metal sheeting and
acrylic panels. The safety screen should be reasonably transparent to allow the ingress of light, allow the
user to view the surroundings and to allow the motorist to see the pedestrian or cyclist.
Wire mesh panels shall have a maximum square grid of 50 x 50 mm with a minimum wire diameter of
4 mm diameter wire or 358 security mesh with a 75 x 13 grid and a minimum wire diameter of 4 mm.
Security mesh should be used where there is an assessed high risk that persons may attempt to climb up
the screen.
Where a pattern is required to meet architectural objectives a second decorative mesh panel (typically a
25 x 25 wire mesh) can be tied to the primary mesh panel to produce a silhouette effect. The minimum
wire diameter of any secondary mesh shall be 3 mm.
Apart from where security mesh is used the maximum aperture of any gap or opening in the safety
screen shall be 50 mm in any direction.
The infill panel shall be securely fastened to reduce the risk of it being stolen.
Design Loadings
Safety screens shall be designed in accordance with AS 5100.
The safety screen shall be designed for the most critical combination of the ultimate dead loads plus one
of the following transient load effects:
Wind loading
The ultimate limit state wind speed and wind loading shall be as specified in AS/NZS 1170.2 for a 500
year return period.
Pedestrian Live Loading
Where the safety screen will also function as a pedestrian barrier an ultimate horizontal live load of
2.25 kPa shall be applied onto the screen from the footway level to 1.1 m above footway level.
General Live Load
An ultimate transverse load of 2 kN applied over an area of 0.2 m by 0.2 m anywhere on the screen.

File no: 94M3917
6 of 7
Appendix 2 - Risk Assessment Matrix
Weightings and scores for risk assessment
Assessment
Factor
Number
Weighting Criteria
Weighting
(W)
Scoring Criteria
Score
(S)
1 Type of road below
Motorway or Restricted Access
Major Public Road
Minor road or footway
10
6
2
Posted speed of road
below
>80 kph
>60 – 80 kph
60 kph or lower
10
9
8
2 Type of bridge 10 Pedestrian or shared path
Road bridge with footway
Road bridge without
footways
10
8
0
3 Distance from school 9
4 Distance from hotel or club 8
5 Distance from youth attraction
venue eg sporting venue,
skateboard park
6
Up to 200m
201m - 400m
401m - 600m
601m - 800m
801m - 1000m
1001m - 1200m
1201m - 1400m
1401m - 1600m
1601m - 1800m
1801m - 2000m
beyond 2000m
10
9
8
7
6
5
4
3
2
1
0
6 Other pedestrian generators
eg Shopping centres, bus & train
stations, high density residential
areas
1 Significant generators within
300m
Minor generators within
300m
None within 300m
10
5
0
7 Lighting 3 Nil
Adjacent lighting
Lighting on bridge
10
5
0
8 Exposure from adjacent buildings 7 Low
Med
High
10
5
0
9 Exposure from passing traffic 7 Low
Med
High
10
5
0
10 History of incidents and/or signs
of graffiti
10 Large amounts of graffiti
and record of past
incidents.
Small amounts of graffiti
No graffiti or past incidents
10
4
0
11 Any loose objects 4 Easily attainable large rocks
or objects
Few shrubs, rubbish & small
rocks
None
10
4
0

The risk rating score is calculated as the sum of the multiplication of the Weighting W and the Score S
divided by number of risk assessment factors:
Risk Rating Score = ∑
×
11
1 11
S
W
Example Risk Assessment
Assessment
Factor No
Description W S W x S
1
A bridge over a major public road that has a
posted speed limit of 70 kph
6 9 54
2 Pedestrian bridge 10 10 100
3 500 m from the nearest school 9 8 72
4 More than 2000 m from a hotel, club 8 0 0
5
More than 2000 m from a youth attraction
venue
6 0 0
6 Within 300 m of a shopping centre 1 5 5
7 Some light from street lights 3 5 15
8
Medium exposure from surrounding
buildings
7 5 35
9 Medium exposure from passing traffic 7 5 35
10
In an area where past incidents of vandalism
have occurred
10 10 100
11 Loose rocks in an adjacent garden bed 4 10 40
Sum of WS 456
Risk Rating Score =
11
456
= 41.5
Risk Rating Score ≥ 30, so a safety screen is required.
File no: 94M3917
7 of 7

Corporate Circular
CC: BTD2011/08
TESTING OF CAST-IN-PLACE CONCRETE PILES
Background
Cast-in-place concrete piles, with or without permanent casing, as specified in RTA QA specifications
B58 and RTA B59 respectively, are often founded in rock of medium strength or better classification to
AS 1726 and were traditionally designed using working stresses. As the examination of pile holes and
socket of piles founded in these materials was considered sufficient to ensure pile strength, the current
versions of RTA B58 and RTA B59 do not specify pile testing.
Following the issue of AS2159-2009, less conservative limit state designs are increasingly being used for
cast-in-place concrete piles. Verification of the geotechnical design resistance of these piles is best
achieved by pile testing in addition to pile hole examination, especially where the pile is founded in soft
rock or weaker stratum. AS 2159-2009 encourages testing of all types of piles, and mandates testing
under certain circumstances, depending on the site conditions and extent of investigation, and the design
assumptions and construction methods.
This Technical Direction details the requirements for the testing of cast-in-place concrete piles to cover
their use when founded in various founding materials and to address the requirements of AS 2159-2009
pending the revision of both RTA B58 and RTA B59. This Bridge Technical Direction supersedes
BTD2010/05 which is now withdrawn.
Information
RTA B58 and RTA B59 are written to conform to AS 5100.3-2004 and AS 2159-1995 which are
referenced in both specifications. Dynamic or other testing of cast-in-place concrete piles is not
specified.
For all pile types, AS 2159-2009 mandates integrity testing where φgb > 0.4, and load testing where both
φgb > 0.4 and the average risk rating (ARR) ≥ 2.5. However AS 2159-2009 allows designers to specify,
where considered necessary, additional testing with φgb ≤ 0.4.
The extent and type of pile testing as revised by AS 2159-2009 is based on the ARR value and designer’s
specific requirements. The new Standard encourages pile testing by permitting use of higher values of φg
when testing is carried out.
Cast-in-place concrete piles for RTA works or those that will be property of RTA shall be tested as
detailed below to confirm:
a. Design geotechnical strength where φgb > 0.4; and
b. Pile integrity using low-strain impact testing methods regardless of φgb value, as detailed below.
Contact: Taha Ahmed
Section: Policy & Specifications, Bridge Engineering
File no: 96M2117, 96M2118 & 94M3917
1 of 4

Contact: Taha Ahmed
File no: 96M2117, 96M2118 & 94M3917
2 of 4
All testing excluding static load testing shall be carried out by RTA approved organisations using RTA
approved processes and equipment included in the Lists of RTA Approved Bridge Components and
Systems at:
http://www.rta.nsw.gov.au/doingbusinesswithus/downloads/listofapprovedbridgecomponentssystems.pdf
Piles selected for testing shall be as nominated on the Drawings or as determined in agreement with
RTA’s geotechnical representative.
(A) Design Geotechnical Strength and/or Serviceability
The minimum percentage and number of piles to be tested at each bridge site for strength and/or
serviceability shall conform to Table 1.
Table 1. Minimum Percentage (1) and Number of Piles (2) to be Tested for
Design Geotechnical Strength
Rock classification(3)
ARR(4)
<3.0 3.0-3.99 4.0-5.0
% 0 0 1
Medium or better
Minimum Number 0 0 1
% 1 2 3
Low (5)
% 2 3 4
Very Low (5)
% 3 4 5
Extremely Low (5)
(1) Fractions shall be rounded up to the next integer
(2) The higher of these two values shall be adopted for testing
(3) Rock classification to AS1726-1993 (not for pile design purposes)
(4) Average risk rating as per AS 2159-2009
(5) Extent of testing for piles founded in low to extremely low strength rock may be increased
depending on site specific conditions in agreement with RTA’s geotechnical representative.
Testing may comprise static loading, high-strain dynamic testing, bi-directional load testing or rapid load
testing as detailed in AS 2159-2009. Unless otherwise specified on the Drawings, the maximum test
load Pg shall be as specified in Clause 8.3.3 of AS2159-2009.
For dynamic testing, the hammer mass shall be such that the net energy imparted to the pile is sufficient
to mobilise the design pile resistance corresponding to the maximum test load. The hammer drop may
be increased incrementally to no more than 3 m until the required resistance is achieved. Testing shall
not result in the allowable concrete stresses being exceeded.
(B) Pile Integrity
Integrity testing may be carried out using any of the integrity testing methods specified in AS 2159-2009.
The minimum percentage and number of piles to be integrity tested at each bridge site using low-strain
head impact testing methods, eg pulse echo (PE) or impulse response (IR), shall conform to Table 2.

Contact: Taha Ahmed
File no: 96M2117, 96M2118 & 94M3917
3 of 4
Table 2. Minimum Percentage (1) and Number of Piles (2) to be Integrity Tested
Using PE or IR Methods
% 20
A(3)
Minimum Number 4
% 25
B(4)
Minimum Number 5
(1) Fractions shall be rounded up to next integer
(3) When pile design load is governed by pile geotechnical capacity
(4) When pile design load is governed by pile shaft structural capacity
PE or IR methods must be capable of testing the full length of the pile taking into account the specific
rate of energy dissipation of the founding material. The maximum length to diameter ratio (L:D) of a pile
to be tested using PE or IR methods shall conform to Table 3 unless otherwise approved by RTA’s
geotechnical representative.
Table 3. Maximum L:D of Piles for Integrity Testing Using PE or IR Methods
Founding Material Rock Stiff/ hard soil Medium stiff soil Very soft soil
Pulse Echo 10 20 40 60
Impulse Response 10 20 30 30
Depending on bridge site conditions and design assumptions, the RTA’s geotechnical representative may
seek validation of PE or IR tests by comparing them to high strain dynamic tests carried out on the same
piles subsequent to their PE or IR testing.
Where use of PE or IR test methods is deemed inappropriate by the RTA’s geotechnical representative
because of bridge site conditions, pile geometry and/or construction methods, Sonic Logging (SL)
methods shall be considered. The extent of SL testing shall be in accordance with Table 4.
Table 4. Minimum Percentage (1) and Number of Piles (2) to be Integrity Tested
Using SL Method
ARR(3)
<2.5 2.5-2.99 3.0-3.49 3.5-3.99 4.0-4.49 4.5-5.0
% 5 10 10 15 15 20
A(4)
Minimum Number 1 2 2 3 3 4
% 15 15 20 20 25 25
B(5)
Minimum Number 3 3 4 4 5 5
(1) Fractions shall be rounded up to next integer
(3) Average risk rating as per AS 2159-2009
(4) When pile design load is governed by pile geotechnical capacity
(5) When pile design load is governed by pile shaft structural capacity

Contact: Taha Ahmed
File no: 96M2117, 96M2118 & 94M3917
4 of 4
Provide at least four cast-in steel logging tubes for every pile to be SL tested. PVC tubes are not
permitted for use in SL testing. The diameter of logging tubes shall be appropriate for the probes to be
used for logging.
References: BTD 2010/05
Principal Bridge Engineer
DISTRIBUTION:
Publication on RTA’s Intranet and the Internet
Senior Geotechnical Engineer, Road Pavement & Geotechnical Engineering, RTA Network Services

Corporate Circular
CC: BTD2011/07
RTA INTERIM CODE FOR CONCRETE DESIGN
Information
The latest edition of AS 3600-2009 introduced several changes to the design of concrete structures
including an increase in the maximum characteristic compressive strength of concrete at 28 days to
100 MPa.
The current edition of the concrete design part of the Bridge Design Code (AS 5100.5-2004) was based
on AS 3600-2001.
RTA has prepared an interim edition of AS 5100.5 that adopts most of the changes in AS 3600-2009 to
enable the improvements in concrete technology reflected in that document to be utilised whilst the
new edition of AS 5100.5 is being prepared. The interim edition also incorporates the contents of RTA
Bridge Technical Directions BTD 2007/10 and BTD 2007/11 and the cement composition requirements
of RTA B80.
However, at this stage the maximum characteristic compressive strength of concrete used in RTA bridge
works at 28 days will not be increased above 65 MPa.
The characteristic compressive strength of concrete at 28 days for RTA bridges, and those bridges that
will become the property of RTA, shall be within the range from 25 to 65 MPa.
Until further notice, the design of concrete bridge members shall be in accordance with the interim
concrete bridge design code AS/RTA 5100.5 April 2011-Interim. The interim document is available on
the RTA’s Internet site and can be accessed at the URL:
http://www.rta.nsw.gov.au/doingbusinesswithus/downloads/as_rta_5100-5_april2011_interim.pdf
References: BTD 2007/10, BTD 2007/11, RTA QA Specification B80
DISTRIBUTION:
Contact: Samia Sedra, Greg Forster, Mark Bennett
Section: RTA Bridge Engineering
File no: 94M3917
1 of 1

Corporate Circular
CC: BTD2011/06
PROVISIONS FOR THE DESIGN OF SUPER-T GIRDER BRIDGES
Information
This Bridge Technical Direction deals with design issues of Super-T girder bridges and sets guidelines to
minimise risks and future costs to RTA. This Bridge Technical Direction supersedes CBE 97/3 which is
now withdrawn.
Main Standard Bridge Drawings dealing with Super-T girder bridges are drawing numbers RTAB033,
RTAB033A to F and RTAB057.
The following provisions shall apply to the design of Super-T girder bridges:
Super-T Girders
1. Internal diaphragms shall be provided at each end of each girder, and shall be sufficiently long to
splay the layers of vertical reinforcement on skew bridges;
2. Intermediate internal diaphragms with a maximum spacing of 8000mm shall be provided for all
girders;
3. Standard Super-T girders shall be 750, 1000, 1200, 1500 and 1800mm deep;
4. Super T- girders for road bridges shall be designed as open type girders with no top flange
between the webs;
5. Minimum web thickness shall be 100mm. A thicker web shall be provided where required for
strength or durability reasons;
6. Nominal concrete cover to the reinforcement on the outside face of the girder shall be 30mm
minimum except for the bottom face of the top flange where the nominal cover shall be 25mm
minimum. A larger cover shall be provided where required for durability. The nominal cover of
the top face of the top flange shall be 20mm minimum. The internal nominal cover of the girder
shall be 25mm minimum;
7. Not more than 50% of the strands shall be debonded at any section. Strands horizontally or
vertically adjacent to a debonded strand, shall not be debonded;
8. The minimum distance from the end of the girder to the bearing centreline measured along the
girder centreline shall be 400mm;
Contact: Warren Stalder
File nos: 94M3917
1 of 3

File nos: 94M3917
2 of 3
9. The maximum nominal aggregate size in the concrete mix design shall be 14mm;
Cross Girders
10. Cross Girders shall be provided at the ends of Super-T girders. Cross girders shall be designed for
jacking up the bridge superstructure for the purpose of bearing replacement in accordance with
RTA Bridge Technical Direction BTD2007/12;
11. Cross girders shall not extend beyond the outside face of edge Super-T girders;
12. Where formed holes are used in Super-T girders to install the cross girder reinforcement, grouting
procedure around the reinforcement shall be detailed on the drawings. For bridge decks with
double cross falls, the use of welding splices or approved mechanical couplers of the threaded
type shall be used. Approved proprietary mechanical grade D500N reinforcing bar splices can be
found at:
http://www.rta.nsw.gov.au/doingbusinesswithus/downloads/listofapprovedbridgecomponentssystems.pd
f
Maximum Span Length for Simply Supported Girders
13. The maximum span, measured centre to centre between bearings, of Super-T girders designed for
SM1600 traffic loading shall be as follows:
o 18 metres for the 750 mm deep girders,
o 33 metres for the 1500 mm deep girders, and
o 37 metres for the1800 mm deep girders;
Bridge Skew
14. Super-T girders shall, unless otherwise approved by the Principal Bridge Engineer, not be used in
bridges with a skew larger than 35 degrees. Where a skew greater than 25 degrees is proposed,
accurate analysis shall be undertaken to account for the skew effects on transverse and
longitudinal bending of the deck and link slabs, and the differential shrinkage effects between the
deck slab and the girders particularly in the vicinity of the acute corners of the bridge deck. Special
attention shall be taken to control cracking of the bridge decks to within specification limits;
Conduits
15. Where required and agreed to by the RTA Asset Manager, allow for the placement of conduits
through super T-girders. Indicate on drawings the locations and size of the required block outs at
the end blocks, internal diaphragms and at abutment curtain walls; and
16. Allow for the installation and replacement of the conduits from a pit behind the abutments
located outside marked traffic lanes. Ensure that the bridge movement during jacking is not
restricted.

File nos: 94M3917
3 of 3
References: CBE 97/3, BTD2007/12, RTA Standard Bridge Drawings RTAB033,
RTAB033A to F and RTAB057
DISTRIBUTION:

Section: New Bridge Design, Bridge Engineering
File no: 94M3917
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Corporate Circular
CC: BTD2010_05
Corporate Circular
CC: BTD2011/05
MINIMUM RESTRAINT CAPACITY FOR SUPERSTRUCTURES
Background
In 2009 the superstructure of an RTA pedestrian bridge at Maitland was dislodged from its supports and
collapsed onto the highway due to the impact from an over height vehicle.
This bridge superstructure had adequate lateral restraint but insufficient vertical restraint at its supports
to resist the impact force from the over height vehicle.
As a result of this bridge collapse the RTA requires that its new bridges be designed to provide a
minimum vertical restraint force to superstructures. Further, the minimum vertical clearance for all
pedestrian, cycleway and shared path bridges is to be standardised at 5.5 m.
Information
Clause 9 of AS 5100.2 -2004 requires the provision of a lateral restraint system for superstructures
capable of resisting an ultimate horizontal force normal to the bridge centre-line of 500 kN. AS 5100.2
has no provision for vertical restraint of the superstructure.
During the impact of a bridge superstructure by an over height vehicle, in addition to the lateral load a
concurrent vertical lifting force is often also applied.
The UK Highway Agency Design Manual for Roads and Bridges Part BD 60/04 (May 2004) recognises
this and requires that for bridge superstructures below a nominated vertical clearance, supports be
designed for a collision load on the superstructure of 500 kN force acting at any inclination between
horizontal and (upward) vertical.
This technical direction shall apply to the design of new RTA bridges and bridges that will become the
property of the RTA over roads and railway lines with a vertical clearance of less than 7.0m, and bridges
over navigable waterways.
To minimise the risk of the superstructure of a bridge being dislodged from the substructure, the
superstructure supports shall be designed for the loads from a minimum ultimate force of 500 kN acting
at any inclination between horizontal and (upward) vertical applied at any potential impact points on the
superstructure, concurrent with minimum permanent downward vertical load acting on the support
multiplied by 0.75. The impact force will be taken to act at the level of the soffit of the superstructure.
The load path for the transfer of the impact force to the substructure shall be determined and the
bearings, restraints, substructure elements and foundations designed for the resulting forces. If uplift
could occur at any support, a restraint system shall be provided to resist the uplift force between the
superstructure and the substructure at the relevant support.

File no: 94M3917
2 of 2
All pedestrian, cycleway and shared path bridges shall have a minimum vertical clearance over the traffic
carriageway of 5.5 m
DISTRIBUTION:

Contact: Ian Hobson
Section: New Design, Bridge Engineering
File no: 94M3917
1 of 1
Corporate Circular
CC: BTD2010_05
Corporate Circular
CC: BTD2011/04
CHANGES TO STANDARD BRIDGE DRAWINGS
RE-ISSUE OF STANDARD BRIDGE DRAWINGS
Background
A by-product of the formation of Transport NSW by the NSW Government, is the requirement that all
transport related agencies in NSW be readily identifiable a common Transport NSW logo.
Information
RTA Standard Bridge Drawings have been revised to replace the old RTA logo with the new Transport
NSW logo as it pertains to the RTA, where applicable.
Further, RTA Standard Bridge Drawings have been revised to include the RTA’s full legal name – that
being the “Roads and Traffic Authority of New South Wales”.
The latest issue number of each RTA Standard Bridge Drawing, as shown on the latest, Issue 51 dated
09 March 2011or subsequent issue of the Standard Bridge Drawings Cover Sheet, shall be used for all
bridge or bridge related projects that are developed by the RTA or for any project that will become the
property of the RTA in the future, effective from the date of this Circular.
DISTRIBUTION:

Contact: Greg Forster
Section: Bridge Engineering
File no: 94M3917
1
Corporate Circular
CC: BTD2011/03
SKID-RESISTANT TREATMENTS FOR BRIDGE DECK JOINTS
Background
Clause 17.3.1 of AS 5100.4 Bridge design – Bearings and deck joints, requires that “metal surfaces wider
than 200 mm, which are exposed to vehicular traffic, shall be provided with an anti-skid treatment.”
Information
Treatment of the trafficked surfaces of bridge deck joints may be required to minimise the risk of drivers
losing control of vehicles traversing the joints in adverse weather conditions of heavy rain.
The RTA has specified, for many years, the application of criss-cross weld beads on its steel fingerplate
joints followed by hot-dipped galvanising after fabrication, with no specific problems reported. This
treatment addresses the aquaplaning situation, by providing a macro-texture to the steel surface that, in
conjunction with the tyre treads, allows the stormwater to be expelled from between the tyre and
treated deck joint surface.
Vehicle tyres in contact with metal surfaces, typically steel or aluminium, in normal dry or wet weather
conditions will usually have sufficient frictional resistance between the rubber tyres and the metal surfaces
to prevent skidding or slipping, except if contaminants such as oil are present on the surface.
Skidding or slipping will occur when frictional resistance is overcome, such as when the vehicle is braked
whilst travelling at excessive speeds or when travelling a tight radius bend at excessive speed, or if oil is
present on the surface. Where oil is present on the surface, it presents a road hazard and must be
removed as soon as possible. This risk cannot be accounted for in the design of the bridge deck joint,
and must be dealt with by road maintenance crews.
The coefficient of friction between the vehicle tyres and the metal surfaces of bridge deck joints has a
wide range of possible values, and is affected by factors such as:
(i) whether the metal surface is wet or dry;
(ii) condition of the surface being rough or smooth, and
(iii) the type of rubber and the age and extent of wear of the tyres.
To reduce the risk of vehicles skidding or slipping on the bridge deck joint, the coefficient of friction can
be increased by applying a coating to the surface that provides an additional micro-texture, the
effectiveness of which depends on the type of coating and its durability.
Application of the additional micro-texture to the metal surface of the bridge deck joint may be required
to give additional frictional resistance, but shall be applied only when deemed necessary following a risk
assessment, as detailed below. RTA approved proprietary slip-resistant coatings are available for this
purpose. However, such coatings wear under traffic, and may need to be regularly inspected and, if
necessary, reapplied periodically.
Details of RTA approved proprietary slip-resistant coatings can be found in the Lists of RTA Approved
Bridge Components and Systems, refer to BTD2008/11.
of 2

Longitudinal metal bridge deck joints parallel to the direction of traffic are sometimes required e.g., when
an existing structure is widened. With time, such longitudinal deck joints can become proud of the
wearing course of the bridge deck as the adjacent asphalt wears away under traffic. The subsequent
issues that occur cannot usually be addressed by the addition of any treatments to the metal surfaces of
such joints. They can only be addressed by milling and replacing the worn asphalt with new fully
compacted dense grade asphalt level with the joint following compaction during placement and from
traffic. However, to minimise risks to traffic that arise from the presence of such joints in the trafficked
part of the roadway, their top surfaces should be given a skid-resistant treatment as detailed below.
All deck joints on new bridges, and replacements for existing joints, exposed to vehicular road traffic with
metal surfaces more than 200 mm wide or long measured in the direction of traffic shall have a skid-
resistant treatment on those surfaces as follows:
(i) For all traffic situations, a grid at 45 degrees to the direction of traffic of intermittent orthogonal
weld beads 3 mm high x 55 mm long spaced at 110 mm in both directions.
(ii) For high-risk traffic situations, see below, weld beads as in Item (i) above together with an RTA
approved proprietary slip-resistant coating.
For the purpose of this Bridge Technical Direction, to assess whether a bridge deck joint requires an
RTA approved proprietary slip-resistant coating, a risk assessment shall be carried out, with following
situations deemed to be high-risk:
(a) Bridges on horizontal alignments with curves less than:
a. 150 m radius with traffic speeds greater than 60 km/hr; or
b. 230 m radius with traffic speeds greater than 80 km/hr; or
c. 450 m radius with traffic speeds greater than 100 km/hr.
(b) Bridges on curves with negative (adverse) crossfall.
(c) Bridges on curves with crossfall less than that specified in the RTA Road Design Guide for the
posted travel speed.
(d) Bridges on vertical alignments with gradients greater than 9%.
(e) Bridges on urban arterial roads at locations with annual average daily traffic (AADT) exceeding
80,000 vehicles.
Reference: BTD2008/11
DISTRIBUTION:
Contact: Greg Forster
Section: Bridge Engineering
File no: 94M3917
2 of 2

File no: 94M3917
1 of 3
Corporate Circular
CC: BTD2010_05
Corporate Circular
CC: BTD2011/02
USE OF CFA PILES ON BRIDGES
Background
Continuous Flight Auger (CFA) piles are constructed by screwing a hollow stem continuous flight auger
into the ground and then pumping concrete into the ground as the auger is withdrawn. A reinforcement
cage is then inserted into the wet concrete.
The RTA has permitted the use of CFA piles on a limited basis as set out in BPC 2004/05.
RTA QA Specification B63 covers the construction of CFA piles.
In recent years there have been considerable improvements in the capability of CFA piling rigs, piling
instrumentation and concrete mixes suitable for CFA piles.
Information
Following a trial of CFA piling carried out on the Tarcutta Hume Alliance a review of the conditions and
limitations of use of CFA has been carried out and are set out below.
It is intended that RTA QA Specification B63 will be revised in the future to incorporate the construction
requirements specified below.
CFA piles can be constructed with a maximum diameter of 1200mm.
This Bridge Technical Direction replaces BPC 2004/05, which is withdrawn.
The scope of this Bridge Technical Direction shall apply to the pile foundations of bridges. It does not
apply to soil supporting structures including retaining walls.
CFA piles can be founded in cohesive and non-cohesive soils and rock.
CFA piles are suitable for uniform soil profiles, cohesive soil formations, and cohesive soil formations
overlaying granular soil formations and granular soil formations where the soil density index of the soil
layers generally increases with depth.
CFA piles are not suitable for use in complex soil profiles with cohesive soil formations inter-bedded
with granular soil layers and with hard layers overlying soft layers. This is because the relative small
penetration of the auger per revolution can result in excessive “draw-in” of surrounding granular material
causing contamination of the concrete.

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The length of socket into rock that can be achieved is dependent on the torque of the piling rig, the
strength of the rock and the nature of the overlaying soils. Reasonable socket length can be achieved in
very low to medium strength rock (UCS<10MPa) overlain by cohesive soils. However, only a short
rock socket will be possible where medium to high strength rock is overlain by granular soils due to the
risk of excessive draw-in. A trial pile installation will be required to demonstrate construction suitability
in marginal ground conditions.
In addition to ensuring suitable geological/ geotechnical conditions the following limitations of use and
construction details for CFA piles shall apply:
1. The length of the pile from the top of pile at installation to the toe of the pile shall not exceed
the limit of a single continuous auger with no breaking or unscrewing of the auger permitted
and with reinforcement to be provided over the full length of the pile.
2. CFA piles shall only be installed vertical and shall not be used as end bearing piles, where the
toe of the pile is located on the top of bedrock with a slope steeper than 1 vertical to 4
horizontal.
3. The designer shall specify a minimum of one geotechnical borehole at a pile location in each
pile group supporting each Pier Column or Abutment. Additional bore holes shall be specified
at each pile group if the distance from the borehole to the pile exceeds 4 m. The bore holes
shall be drilled prior to the construction of CFA piles with adequate laboratory and/or in-situ
testing for geotechnical parameter determination. Additional geotechnical boreholes shall be
specified where the ground conditions are complex. All of these boreholes shall be cement
grouted upon completion.
4. To ensure the workability of the concrete to allow the reinforcement cage to be inserted, CFA
piles shall only be used at sites where an uninterrupted supply of concrete can be ensured for
each pile and where travel time of the concrete agitator to site is less than 45 minutes after
adding cement to the aggregates and discharge of the concrete into the pile is completed
within 90 minutes of adding cement to the aggregates. The reinforcement cage shall be
inserted immediately after concreting.
5. The minimum nominal cover to the reinforcement shall be 100 mm but the cover spacers
provided on the reinforcement cage shall be 25 mm less than the nominal cover to facilitate
insertion of the cage. For durability purposes the cover shall be taken to be the nominal cover
minus 25mm.
6. A suitably experienced Geotechnical Engineer representing the design consultant is required to
be present during the construction of the first CFA pile group for each representative
geological condition.
7. A copy of the monitoring records of the parameters specified in Specification B63 shall be
made available to the Geotechnical Engineer within 24 hours of the completion of the pile,
where mobile phone reception is available at the site and within 48 hours otherwise. Apart
from the automatic depth reported in the records, the drilling frame shall be marked clearly at
half metre intervals for independent visual verification.
8. The amount of required concrete over-supply during concreting shall be determined prior to
any contract pile installation and appropriate to the ground conditions. The target value shall
be calculated so that the tip or toe of the auger always remains encased within the concrete.
9. All piles shall be integrity tested and representative piles that are founded in low or less
strength rock shall be load tested at the frequency nominated in BTD 2010/05.
10. The concrete volume reported by the piling instrumentation shall be checked against the
volume of concrete delivered to the pump to confirm the calibration factor for the concrete
supply.

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11. To ensure the base of the pile socket is clean, a multi-pass technique with a minimum of two
passes shall be adopted. After commencement of the discharge of concrete the auger shall be
withdrawn 500 mm. The auger shall then be drilled back down to the toe of the pile to pick
up any contaminated concrete before re-commencing to concrete the pile while withdrawing
the auger. The construction/monitoring records need to show evidence of verification of the
multi pass technique.
References: BPC 2004/05, BTD 2010/05
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File nos: 94M3917 and 99M1468
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Corporate Circular
CC: BTD2011/01
USE OF PROPRIETARY PRECAST REINFORCED CONCRETE MODULAR
BRIDGE DECK SYSTEMS
Background
BTD 2010/01 restricted precast reinforced concrete modular deck systems to use on low speed, low
traffic roads. Circumstances have sufficiently changed that some of the restrictions on traffic volumes can
now be eased.
Information
This Bridge Technical Direction specifies the conditions of use of proprietary modular concrete bridge
deck systems by RTA and supersedes BTD2010/01, which is now withdrawn.
Proprietary modular concrete bridge deck systems shall not be used for RTA bridges and those that will
become the property of the RTA, where:
• For single span bridges the posted speed limit exceeds 100 km/hour; or
• For multiple span bridges the posted speed limit exceeds 80 km/hr; or
• The current or 30 year projected Annual Average Daily Traffic (AADT) exceeds 1500; or
• The current or 30 year projected Average Annual Daily Truck Traffic (AADTT) exceeds 500.
Where proprietary modular concrete bridge deck systems are used, the following conditions shall apply:
a) The bridge and its components shall be designed in accordance with AS 5100 and constructed
in accordance with relevant RTA QA specifications;
b) All deck units shall be pre-cambered to compensate for dead load, shrinkage and creep
deflections so that long-term sagging does not occur;
c) Detailed analyses shall be carried out on the effects of load shedding and traffic barrier loading
to ensure that the design stresses for the edge beam reinforcement will not exceed the limits
specified in AS 5100.5;
d) The anchorage of the main positive moment reinforcement past the inside face of the bearings
shall be in accordance with Clause 8.1.8 of AS 5100.5. Where cogged or hooked bars are used,
the drawings shall specify that the reinforcing bars are to be accurately bent to the required
dimensions, to ensure correct cover at the ends of the units;
e) Adjacent deck units shall be transversely prestressed or connected by in-situ reinforced concrete
stitch pours to ensure full transverse flexural continuity;
f) Full depth diaphragms shall be provided at the ends of all deck units. Intermediate diaphragms shall
be provided as required;
g) Diaphragms shall be designed to be fully prestressed under serviceability loading;

File nos: 94M3917 and 99M1468
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h) As an alternative to in-situ grouting of transverse tendons in accordance with RTA QA
Specification B113, factory pre-grouted tendons in polyethylene sheathing may be used. In this
case, the tendons shall be taken to be un-bonded;
i) The number of transverse deck expansion joints shall be minimised and shall have a minimum
spacing of not less than 25m;
j) Where applicable, gaps in shear keys and between adjacent precast units shall be fully sealed to
prevent leakage during grouting. In particular, leakage of grout on the bearing shelf shall be
prevented to avoid compromising the performance of any bearing; and
k) Proprietary modular concrete bridge deck systems are required to incorporate a waterproof
membrane in order to comply with BPC2003/02.
References: BPC2003/02, BTD2010/01
DISTRIBUTION:

Corporate Circular
CC: BTD2010/04
ISSUE OF NEW STANDARD BRIDGE DRAWING
ISSUE OF NEW STANDARD BRIDGE DRAWING No RTAB100 – DESIGN
AND CONSTRUCTION AND ALLIANCE TEAM PROJECT DRAWING SHEET
Background
The development of bridge and related projects by Design and Construction and Alliance teams has
seen the need to develop a standard A1 size drawing template that provides space for participants’
names and can be used for both bridge and road construction drawings.
RTA Standard Bridge Drawing No RTAB100 has been prepared for use by Design and Construction and
Alliance teams so that there can be consistency of drawing presentation for projects developed for the
RTA, irrespective of design discipline.
Information
RTA Standard Bridge Drawing No RTAB100 provides for the inclusion of both the design consultant’s
and construction company’s details, a revision schedule and necessary computer reference file details.
RTA Standard Bridge Drawing No RTAB100 shall be used for Design and Construction contracts or by
Alliance teams for any bridge or bridge related project that is developed for the RTA or for any project
that will become the property of the RTA in the future, effective from the date of this Circular.
DISTRIBUTION:
Section: Bridge Engineering (New Design)
File no: 94M3917
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Corporate Circular
CC: BTD2010/03
PRETENSIONED BRIDGE MEMBERS – CONCRETE TRANSFER STRENGTH
REQUIREMENTS
Background
Chief Bridge Engineer Circular, CBE No 94/6 (CBE1994/06), introduced a limit on the transfer strength
of pre-tensioned bridge members to 35 MPa. The main purpose of this limit was to restrict the 28 day
strength to 50 MPa for ductility reasons and to reduce costs.
It is now considered that the higher strength mixes are better understood by designers and constructors
and more often utilised for bridge products in order to reduce overall cost.
The concrete transfer strength used in the design of pre-tensioned bridge members for RTA owned
bridges should not be greater than 40 MPa without the written approval of the Principal Bridge Engineer.
CBE1994/06 is withdrawn.
References: CBE1994/06
DISTRIBUTION:
Section: Policy & Specifications, RTA Bridge Engineering
File no: 94M3917
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Contact: Amie Nicholas
Section: Rehabilitation Design, RTA Bridge Engineering
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TIMBER BRIDGE DESIGN - ADOPTION OF AS 1720.1-2010
Background
Since the introduction of the limit state design method in the Austroads Bridge Design Code in 1992,
there has not been an associated limit state timber bridge design code. The last applicable code was the
working stress design version in the 1976 NAASRA Bridge Design Specification.
For timber design, this code invoked AS 1720:1975 SAA Timber Structures Code. Since 1975 there
have been three further editions produced of AS 1720, in 1988, 1997, and most recently in June 2010.
The amendments made since 1975 have significant implications for the design strengths of timber
members. The 2010 edition in particular offers significant benefits in design.
The limit state timber design code AS1720.1-2010 shall be used until further notice for the design of
new timber bridges and for timber bridge assessment and rehabilitation designs for RTA bridges and
those that will become the property of the RTA.
AS 1720.1-2010 shall be used in conjunction with the attached appendices:
• Appendix A – Design Loading for Timber Bridges
• Appendix B – Timber Bridge Design Parameters
• Appendix C – Modelling Guidelines for Timber
DISTRIBUTION:
Corporate Circular
CC: BTD2010/02

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APPENDIX A: DESIGN LOADINGS FOR TIMBER BRIDGES
Design loadings for timber bridges shall comply with AS 5100.2, excluding only Sections 5, 6 and 9.
The minimum additional design loadings and load factors for timber bridges shall be as follows:
Dead Loads
The minimum dead load per unit volume of any timber component shall be taken as 11 kN/m3.
The design dead loads and superimposed dead loads for serviceability and ultimate limit states shall be
obtained by applying the appropriate load factor in Table 1 to the nominal loads on the structure.
Where the dead load is calculated from the dimensions shown on the drawings, the “design case” load
factor applies. Where an assessment of an existing member is being undertaken, and dead load is
calculated from actual dimensions measured on site, the “direct measurement” load factor applies.
Care shall be taken to ensure that all metal components (such as cast metal shoes and splice plates) are
included in dead load calculations. A load factor of 1.1 shall be applied to metal components.
Live Loads
Design live loads shall comply with the following clauses of AS 5100.7 Appendix A, with the load factors
in Table 1 below:
• A2.2.2 T44 Truck Loading;
• A2.2.5 Number of Lanes for Design and Lateral Position of Loads;
• A2.2.6 Modification Factors for Multiple Lane Bridges; and
• A2.2.7 Design for Localised Load Effects – W7 Wheel Loading.
The Dynamic Load Allowance (DLA) for timber bridges shall not be less than 0.2 irrespective of the
expected vehicle speed. The DLA applies to both the ultimate and serviceability limit states.
The design action is equal to: (1 + DLA) x load factor x action under consideration.
Braking effects of traffic shall be considered as a longitudinal force acting at deck surface level. Braking
forces shall be applied in either direction. Irrespective of the width of the structure, the nominal
longitudinal force shall not be less than 200 kN, with the load factors in Table 1.1
To ensure that the superstructure has sufficient lateral restraint to resist lateral forces not otherwise
allowed for in the design, a positive lateral restraint system between the superstructure and the
substructure shall be provided at abutments and piers. The restraint system shall be capable of resisting
a minimum ultimate design horizontal force perpendicular to the bridge centreline of 200 kN at each
abutment and pier, which need not be loaded concurrently. A load factor of 1.0 shall be used.
1
This nominal braking force of 200kN is the minimum requirement of AS5100, and is approximately equivalent to
a T44 truck braking with a deceleration of 0.45g. This also corresponds to a 42.5 tonne vehicle (current legal load)
stopping with a deceleration of 0.48g. Testing in Australia has shown that for general driving conditions in a
60km/h speed zone, trucks decelerate at approximately 0.3g (stopping distance of 47m), but in urgent situations
trucks have been shown to achieve decelerations up to 0.75g (stopping distance of 19m). The Australian design
rules require braking systems to be capable of decelerating heavy vehicles at a minimum rate of approximately
0.45g. The ultimate limit state braking forces that have been adopted correspond to a range of mass and
deceleration rates that are considered reasonable for the expected traffic conditions on RTA timber bridges.

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Table 1: Load Factors for Timber Bridge Design
Ultimate Limit States
Type of Load Serviceability
Limit State Load Reduces Safety Load Increases Safety
Dead Load (design case) 1.0 1.4 0.8
Dead Load (direct measurement) 1.0 1.2 0.9
Superimposed Load 1.0 2.0 0
W7 Wheel Loading + DLA 1.0 2.0 N/A
T44 Truck Loading + DLA 1.0 2.0 N/A
Braking Force 1.0 1.8 N/A
APPENDIX B: TIMBER BRIDGE DESIGN PARAMETERS
Capacity Factor (φ)
Values of capacity factor (φ) for calculating the design capacity of structural members (Rd) and structural
joints (Nd) shall be taken from AS 1720.1-2010 Tables 2.1 and 2.2, Category 3 (primary structural
members or joints in structures intended to fulfil an essential service or post disaster function).
For example,
φ = 0.75 for sawn timber (F-grades F17 and higher)
φ = 0.60 for round timbers
φ = 0.60 for bolts larger than M16
φ = 0.75 for bolts M16 and smaller
Values of capacity factor (φ) for calculating the design capacity of secondary members (such as deck
planking, sheeting, timber railings, or other members whose failure could not result in collapse of a
significant portion of the structure) or joints in such members may be taken from AS 1720.1-2010 Tables
2.1 and 2.2 Category 1 (secondary members in structures other than houses).
Characteristic Values for Design
The characteristic strength properties in bending, tension, compression and shear and characteristic
stiffnesses for the design of structural timber elements shall be taken from AS 1720.1-2010 Table H2.1.
The relevant portion of AS 1720.1-2010 Table H2.1 is replicated in Table 2, with notes as follows.
• The characteristic values in Table 2 for bending apply for beams not greater than 300 mm in
depth. For beams greater than 300 mm depth the characteristic values shall be obtained by
multiplying the value in Table 2 by (300/d)0.167, where d is the depth of the section.
• The characteristic values in Table 2 for tension apply for tension members with largest cross-
sectional dimension not greater than 150 mm. For tension members with a cross-sectional
dimension greater than 150 mm, the characteristic values shall be obtained by multiplying the
value in Table 2 by (150/d)0.167, where d is the width or largest dimension of the cross-section.

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Table 2: Characteristic Values for Timber Design (MPa)
Stress
Grade
Bending
(f’b)
Tension
parallel to
grain (f’t)
Shear in
beam (f’s)
Compression
parallel to grain
(f’c)
Modulus of elasticity
parallel to grain (E)
Modulus of
rigidity (G)
F27 67 42 5.1 51 18 500 1 230
F22 55 34 4.2 42 16 000 1 070
F17 42 25 3.6 34 14 000 930
When determining the appropriate stress grade, reference shall be made to RTA QC Specification 2380,
Table 2380/1, Strength and Durability Requirements. In the absence of information to the contrary, the
minimum stress grade given in RTA 2380, Table 2380/1 shall be used for design purposes.
Duration of Load Factor k1
Values for the duration of load factor k1 for the strength of timber shall be as follows:
• k1 = 0.57 for permanent actions e.g., dead load, superimposed load, loads due to earth pressure
• k1 = 0.80 for serviceability live load
• k1 = 0.97 for ultimate live load
• k1 = 1.00 for other ultimate actions e.g., braking force, minimum lateral restraint, log impact
Values for k1 for the strength of joints with laterally loaded fasteners shall be as follows:
• k1 = 0.57 for permanent actions e.g., dead load, superimposed load, loads due to earth pressure
• k1 = 0.69 for serviceability live load
• k1 = 0.86 for ultimate live load
• k1 = 1.00 for other ultimate actions e.g., braking force, minimum lateral restraint, log impact
Note that in accordance with Clause 2.4.1.1, for any given combination of loads of differing duration, the
factor k1 to be used is that appropriate to the action that is of the shortest duration. For example, when
considering ultimate dead load plus ultimate live load, the appropriate member k1 factor is 0.97.
Generally, the forces due to dead load in most timber elements in a bridge are quite small compared to
those caused by live loads. However, some components in large span trusses may be subjected to
relatively high dead load forces. Dead load should, therefore, also be considered by itself or combined
with other permanent loads in such cases using k1 of 0.57 for permanent actions.
Strength Sharing Factor k9
The strength sharing factor k9 is only applicable to the design of members for bending. One basic
condition for its application is that for a parallel system (such as girders in a timber deck), in the event of
the failure of a single supporting member (such as a girder) then the overlying members (such as decking
planks) shall be capable of transferring loads to adjacent supporting members. In such cases, if decking
planks have insufficient strength to transfer the load with one girder missing, then k9 shall be taken as 1.0.
The method outlined in Appendix C, “Distribution of Wheel Loads on Timber Decks” shall be used to
determine the number of planks assumed to carry the load.

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Detailing of Joints – Factors k16 and k17 for Bolted Joints
Thick steel side plates can increase the capacity of a bolt in bearing on the timber by restricting bolt
rotation within the members. In order for this to be effective, the plate must be thick enough to give
effective bending restraint against forces in either direction. The plate must also be stiff enough in
bearing to provide the angular restraint to the bolt that is needed to induce double curvature in it.
When deciding upon a value of k16 the following shall be considered:
• k16 shall generally be taken as 1.0; and
• k16 may be taken as 1.2 for bolts that transfer load through two metal side plates, one on each
side of the timber, only where the bolts are a close fit to the holes in these plates, and where
metal plates are of adequate strength and stiffness to induce double curvature in the bolt.
In accordance with AS 1720.1-2010 Clause 1.4.4.4, when using unseasoned timber, consideration shall
be given to the effects of shrinkage. For most timbers, the magnitude of shrinkage is in the range of 0.1%
to 0.3% in the direction of the wood grain and 2% to 10% transverse to the grain. According to
Clause 4.4.3.2, the possibility of restraint to timber shrinkage due to the detailing of bolted joints in
unseasoned timber causes a loss of capacity equivalent to specifying half the number of bolts. In addition
to the loss of capacity, there is a risk to durability of the timber through inducing premature splitting and
allowing moisture ingress. Joints shall therefore be detailed to ensure no restraint to timber shrinkage.
Two examples are shown in Figure 1 below of poor detailing which restrains timber shrinkage.
Figure 1: Timber shrinkage restrained by steel plate and by longitudinal grain (i.e., k17 = 0.5)
Round Timbers – Shaving Factor k21
Where round timbers are used (such as in pier trestles or girders), these shall be designed and assessed
in accordance with Section 6 of AS1720.1-2010. Where these members are shaved on one or more
faces, assume that the shaving will reduce the modulus of elasticity by 5% in accordance with
Clause 6.4.2. The shaving factor k21 shall be taken from Table 6.3, except for the case of bending where
only the compression face of the round timber is shaved. For this case, k21 may be taken as 0.95. This
situation will commonly occur in the case of girder spans, where the tops of the girders are shaved to
provide a flat bearing surface for the decking.
STEEL PLATE
TIMBER MEMBER
UNSEASONED TIMBER MEMBER
UNSEASONED TIMBER MEMBER
SHRINKAGE DIRECTION
SPLITTING

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APPENDIX C: MODELLING GUIDELINES FOR TIMBER
General Considerations
The majority of traditional timber bridge designs utilise systems that do not provide a high degree of
composite action or continuity between components. In addition, the systems are usually quite
susceptible to the effects of repeated loads and so the structural response can change with time.
In general, regardless of any refined analytical methods that may be used (such as grillage or frame
analysis), a simplified conservative analysis shall also be performed for comparison. This simplified
method shall assume no continuity in members and simple supports. If the simplified method displays
inadequate strength, then the two methods shall be compared to determine how much improvement in
performance is needed. It is usually unlikely that a timber system will perform as an integral unit except
in the case of Stress Laminated Timber (SLT) deck systems. The timber system will perform somewhere
in between, depending on the bridge’s condition.
Distribution of Wheel Loads on Timber Decks
Whilst it is possible to analyse a timber girder and decking system as a grillage, this assumes that the deck
is a two-way continuous structure and may provide a non-conservative result. Guidelines are therefore
given below regarding how to distribute vehicular loadings to timber bridges.
For timber decks that do not have any sheeting, only those components directly in contact with the
design wheel (tyre) load will share the load. This will depend upon the following variables:
• Design load under consideration (i.e. T44 or W7);
• Orientation of the decking (transverse or diagonal); and
• Width of the decking.
Typically, the decking is transverse and is usually wider than 200 mm. In this case, the wheel contact
length of 200 mm will be carried by only one deck plank. The span of the decking without sheeting
should be taken as the clear distance between the supports and assumed to be simply supported.
Although physically the decking is continuous over the girders, it will rarely act as a continuous member
unless all the bolts across the deck for all the decking are very tight at all times. The latter is impractical,
rarely achieved and never maintained. The conservatism introduced by assuming a simply supported
span is offset slightly by assuming the span is the clear distance between supporting girders.
For timber decks that are overlaid with sheeting, some additional distribution of load can be assumed to
take place. The number of deck planks sharing the load will depend upon the following variables:
• Design load under consideration (i.e., T44 or W7);
• Orientation of the decking (transverse or diagonal);
• Width and depth of the decking; and
• Depth of the sheeting.
Typically, the sheeting is longitudinal on transverse decking. The load can be assumed to disperse
through the sheeting and decking at an angle of 56° (consistent with the principle of disregarding design
shear actions within a distance of 1.5 times the depth of a member). The distribution width (in the
direction of the traffic) would therefore be equal to (contact length = 200) + (3 x depth of sheeting) +
(depth of decking) rounded up to the nearest full number. For example, with 75mm sheeting and 100
mm decking, the assumed distribution width for the deck is 200 + (3 x 75) + 100 = 525 mm. The
number of deck planks supporting the load may then be calculated as (distribution width) / (plank width),
so for 200 mm wide decking, this gives 2.6 which would then be rounded up to 3 deck planks.

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