AGBT01-18 Guide To Bridge Technology Part 1 Introduction and Bridge Performance

Guide to Bridge Technology Part 1:
Introduction and Bridge Performance
Sydney 2018
Guide to Bridge Technology Part 1: Introduction and Bridge Performance
Publisher
Second edition prepared by: Hanson Ngo
Austroads Ltd.
Level 9, 287 Elizabeth Street
Second edition project manager: Henry Luczak Sydney NSW 2000 Australia
Phone: +61 2 8265 3300
Abstract
austroads@austroads.com.au
Austroads Guide to Bridge Technology provides bridge owners and agencies www.austroads.com.au
with advice on bridge ownership, design procurement, vehicle and pedestrian
accessibility, and bridge maintenance and management practices. The Guide About Austroads
has eight parts.
Austroads is the peak organisation of Australasian
Part 1 provides general information about bridge design and construction. road transport and traffic agencies.
Topics covered in this Part include factors affecting bridge performance, their
relationship to bridge design standards, and the evolution of bridges and Austroads’ purpose is to support our member
bridge loadings. Technical and non-technical design influences are also organisations to deliver an improved Australasian
discussed along with the evolution of bridge construction methods and road transport network. To succeed in this task, we
equipment. Specifications and quality assurance in bridge construction is also undertake leading-edge road and transport
addressed. research which underpins our input to policy
development and published guidance on the
design, construction and management of the road
Keywords
network and its associated infrastructure.
Evolution of bridges, design parameters, steel girder bridges, suspension
Austroads provides a collective approach that
bridges, timber bridges, steel truss bridges, truss-arch bridges, cable stay
delivers value for money, encourages shared
bridges, history of bridges, durability, reliability, design, materials,
knowledge and drives consistency for road users.
components, construction, maintenance, operation, quality assurance, skew
bridges, structural drawing Austroads is governed by a Board consisting of
senior executive representatives from each of its
eleven member organisations:
Second edition published February 2018
• Roads and Maritime Services New South Wales
First edition published May 2009
• Roads Corporation Victoria
• Queensland Department of Transport and Main
ISBN 978-1-925671-22-3 Roads
Austroads Project No. BT1830 Pages 57 • Main Roads Western Australia
Austroads Publication No. AGBT01-18 • Department of Planning, Transport and
Infrastructure South Australia
• Department of State Growth Tasmania
© Austroads Ltd 2018
• Department of Infrastructure, Planning and
This work is copyright. Apart from any use as permitted under the Logistics Northern Territory
Copyright Act 1968, no part may be reproduced by any process without
• Transport Canberra and City Services
the prior written permission of Austroads.
Directorate, Australian Capital Territory
• Australian Government Department of
Acknowledgements Infrastructure and Regional Development
First edition prepared by Geoff Taplin and John Fenwick and project managed
• Australian Local Government Association
by Geoff Boully. • New Zealand Transport Agency.
This Guide is produced by Austroads as a general guide. Its application is discretionary. Road authorities may vary their practice
according to local circumstances and policies. Austroads believes this publication to be correct at the time of printing and does not
accept responsibility for any consequences arising from the use of information herein. Readers should rely on their own skill and
judgement to apply information to particular issues.
The latest edition provides updated details and information on various sections, and the removal of overlapping information. Major
changes include:
• update Section 2.1 and Section 2.2 to reflect the current versions of AS 5100 and NZ Transport Agency Bridge Manual
• the addition Section 3.10: The development of bridge design standards
• update of Section 3.12: Safety in design and occupational health and safety
• revision of Section 5 to ensure that background information on quality assurance in bridge projects aligns with the current
AS/NZS ISO 9000 and AS/NZS ISO 9001
• additional discussion related to various quality assurance issues in bridge projects.
Contents
1. Introduction............................................................................................................................................. 1
1.1 Scope ....................................................................................................................................................... 1
1.2 Guide Structure ........................................................................................................................................ 1
2. Relationship to Bridge Design Standards ........................................................................................... 3

2.1 Scope of AS 5100..................................................................................................................................... 3
2.2 Scope of NZ Transport Agency Bridge Manual ........................................................................................ 4
2.3 Confirmation of Design Parameters by the Road Agency........................................................................ 4
3. Influences on the Evolution of Australian and New Zealand Bridges .............................................. 5

3.1 Timber Bridges in Australia ...................................................................................................................... 5
3.2 The Age of Iron and Steel ........................................................................................................................ 6
3.3 Steel Truss and Truss-arch Bridges ......................................................................................................... 9
3.4 Steel Girder Bridges ............................................................................................................................... 10
3.5 Suspension Bridges................................................................................................................................ 11
3.6 Cable Stay Bridges ................................................................................................................................. 12
3.7 The Rise of Concrete Bridges ................................................................................................................ 13
3.8 Bridge Aesthetics and Urban Design ..................................................................................................... 16
3.9 Other Singular Events of Influence......................................................................................................... 16
3.10 The Development of the Bridge Design Standard .................................................................................. 16
3.10.1 NAASRA Bridge Design Code.................................................................................................. 16
3.10.2 1992 Austroads Bridge Design Code ....................................................................................... 16
3.10.3 HB 77-1996 Australian Bridge Design Code ............................................................................ 17
3.10.4 Standards Australia AS 5100 Bridge Design ............................................................................ 17
3.11 The Development of Bridge Design Loading ......................................................................................... 17
3.11.1 A History of Bridge Design Loads............................................................................................. 17
3.11.2 Current Design Traffic Loading and Design Life ...................................................................... 18
3.12 Safety in Design and Occupational Health and Safety .......................................................................... 19
3.13 Future Influences on the Evolution of Australian and New Zealand Bridges .........................................19
4. Factors Affecting Bridge Performance .............................................................................................. 21

4.1 Durability, Robustness and Reliability of Bridges ................................................................................... 21
4.2 Design .................................................................................................................................................... 21
4.3 Materials ................................................................................................................................................. 24
4.4 Components ........................................................................................................................................... 28
4.5 Construction ........................................................................................................................................... 34
4.6 Maintenance and Operation ................................................................................................................... 41
5. Quality Assurance in Bridge Projects ................................................................................................ 43

5.1 Introduction ............................................................................................................................................. 43
5.2 Applicable Standards/Legislative Requirements .................................................................................... 43
5.3 QMS Models ........................................................................................................................................... 44
5.3.1 Quality Management (QM) Principles ...................................................................................... 45
5.3.2 Requirements for Agencies ...................................................................................................... 46
5.3.3 Requirements for Service Providers ......................................................................................... 47
5.4 QA Issues in Bridge Projects .................................................................................................................. 48
5.4.1 QA Interactions in a Bridge Contract ........................................................................................ 48
5.4.2 Timescale and Durability .......................................................................................................... 49
5.4.3 QA in Different Procurement Models ........................................................................................ 50
5.4.4 Pre-qualification and Pre-registration ....................................................................................... 52
5.4.5 Control of Nonconforming Products ......................................................................................... 53
5.4.6 Hold Points and Witness Points ............................................................................................... 54
5.4.7 Inspection and Testing ............................................................................................................. 54
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References ...................................................................................................................................................... 55
AS/NZS ISO 9001 Clauses for Consideration ....................................................................... 57
Tables
Table 1.1: Parts of the Guide to Bridge Technology .................................................................................. 1
Table 3.1: Design eras in Australia .......................................................................................................... 18
Table 3.2: Design eras in New Zealand ................................................................................................... 18
Figures
Figure 3.1: Iron Bridge, Coalbrookdale ....................................................................................................... 6
Figure 3.2: St Louis Bridge under construction ........................................................................................... 8
Figure 3.3: Opening of the welded construction University Footbridge across the Torrens,
1937 ........................................................................................................................................ 11
Figure 3.4: Anzac Bridge, Australia’s longest span cable stayed bridge ..................................................12
Figure 3.5: Annandale sewer aqueduct, the oldest extant use of Monier Concrete in
Australia .................................................................................................................................. 14
Figure 4.1: Cracking at a halving joint ....................................................................................................... 22
Figure 4.2: End block cracking in a pretensioned precast beam .............................................................. 23
Figure 4.3: Flexural cracking in reinforced concrete ‘U-slab’ bridge beams .............................................24
Figure 4.4: Corrosion in reinforced concrete beams ................................................................................. 25
Figure 4.5: Early stages of corrosion of steel plate girders ....................................................................... 25
Figure 4.6: Marine organism attack of a timber pile .................................................................................. 26
Figure 4.7: Fibre reinforced polymer used for bridge strengthening .........................................................27
Figure 4.8: Pretensioned precast bridge beam after exposure to fire .......................................................28
Figure 4.9: Poorly compacted concrete at an expansion joint – example 1 .............................................29
Figure 4.10: Poorly compacted concrete at an expansion joint – example 2 .............................................29
Figure 4.11: Failure of a finger plate expansion joint due to disintegration of the concrete .......................30
Figure 4.12: Reinforcement detailing at expansion joint anchor bolts ........................................................30
Figure 4.13: Steel rocker bearing ................................................................................................................ 31
Figure 4.14: Laminated elastomeric bearing ............................................................................................... 32
Figure 4.15: Fatigue failure of sign gantry anchor bolts .............................................................................. 33
Figure 4.16: Fatigue failure of a light pole mast .......................................................................................... 33
Figure 4.17: Grouting a sign gantry base plate ........................................................................................... 34
Figure 4.18: Collapse of beams during construction due to lack of temporary bracing ..............................35
Figure 4.19: Spalling of skew precast beams ............................................................................................. 35
Figure 4.20: Collapse of reinforcing spacer in a bored pile ......................................................................... 36
Figure 4.21: Exposed reinforcing in a bored pile......................................................................................... 37
Figure 4.22: Inclusions in a bored pile ........................................................................................................ 37
Figure 4.23: Inadequate concrete compaction at the top of the in situ concrete ........................................38
Figure 4.24: Crack repair as a result of early age cracking ........................................................................ 39
Figure 4.25: Deck slab core showing extent of crack and repair ................................................................ 39
Figure 4.26: Welding of reinforcing steel at bends can cause loss of strength and ductility ......................40
Figure 4.27: Tensioning of bolts against a painted surface ........................................................................ 41
Figure 4.28: Scour of a bridge abutment..................................................................................................... 42
Figure 5.1: Quality interactions in a typical construction-only bridge contract ..........................................44
Figure 5.2: PDCA cycle ............................................................................................................................. 46
Figure 5.3: Failure rates versus service life of a product .......................................................................... 49
Austroads 2018 | page ii

1. Introduction
1.1 Scope
The purpose of the Austroads Guide to Bridge Technology (AGBT) is to provide guidance to bridge owners
and authorities on technology related issues relevant to bridge ownership, design procurement, vehicle and
pedestrian accessibility and bridge maintenance and management practices, including the use and
application of Australian and New Zealand bridge design standards. Bridge owners are a diverse group
including state road agencies, toll road concessionaires, local governments, private landowners and
businesses such as shopping centre owners.
The AGBT has also been written with the young engineer in mind, particularly those recently graduated and
looking at specialising in the design and construction of bridges. It provides a step-by-step approach to
bridge construction, discussing the learning’s from the past, the planning process, building materials
commonly used, the various types of bridge designs, the issues to consider at the design stage and the
management and ongoing maintenance issues of completed structures.
The AGBT compiles existing available material from Austroads members and elsewhere into a Guide which
provides an Australasian approach to bridge technology that covers the majority of road agency
requirements. The Guide also identifies and references specific locally applied areas of practice or
standards.
A particular output of the Guide is to identify issues where further study and research may provide benefits.
1.2 Guide Structure
The AGBT is published in eight parts and addresses a range of bridge technology issues, each of which is
summarised in Table 1.1.
Table 1.1: Parts of the Guide to Bridge Technology
Part Title Content

Part 1 Introduction and • Scope of the Guide to Bridge Technology and its relationship to the bridge design
Bridge Performance standards.
• Factors affecting bridge performance and technical and non-technical design
influences.
• Evolution of bridges, bridge construction methods and equipment and bridge
loadings.
• Specifications and quality assurance in bridge construction.
Part 2 Materials • The full range of bridge building materials including concrete, steel, timber and non-
metallic components.
• Material characteristics including individual stress mechanisms.
Part 3 Typical Bridge • Superstructure and substructure components – namely timber, steel, wrought iron,
Superstructures, reinforced and pre-stressed concrete.
Substructures and • Typical bridge types such as suspension, cable stayed and arched types.
Components
• Bridge foundations.
Part 4 Design • Bridge design process procurement models, specification requirements, design and
Procurement and delivery management processes, design checking and review concepts, the use of
Concept Design standardised components, aesthetics/architectural requirements, standard
presentation of drawings and reports, designing for constructability and
maintenance.
• Service life of the structure and components, mining and subsidence, flood plains,
bridge loadings, and geotechnical and environmental considerations.
Austroads 2018 | page 1

Part Title Content

Part 5 Structural Drafting • Detailed drawing aspects required to clearly convey to the consultant/construction
contractor the specifics of the project.
• Standards including details required for cost estimating and material quantities.
• Reinforcement identification details.
Part 6 Bridge Construction • Guidance to the bridge owner's representative on site.
• Focuses on bridge technology, high-risk construction processes e.g. piling,
pre-stressing, and the relevant technical surveillance requirements during the
construction phase.
• Bridge geometry, the management of existing road traffic and temporary works.
Part 7 Maintenance and • Maintenance issues for timber, reinforced and pre-stressed concrete, steel,
Management of wrought and cast iron bridges.
Existing Bridges • Maintenance of bridge components including bridge bearings and deck joints.
• Monitoring, inspection and management of bridge conditions.
Part 8 Hydraulic Design of • Waterway design of bridge structures
Waterway • Design flood standards and estimation methods, general considerations in
Structures waterway design and design considerations of waterway structures.
• Design of new bridges for scour, as well as monitoring and evaluation of scour at
existing bridge sites.

2. Relationship to Bridge Design Standards
Bridges in Australia and New Zealand are currently designed in accordance with AS 5100 (Bridge Design),
and the NZ Transport Agency Bridge Manual (NZ Transport Agency 2016a) respectively. The AGBT is not
intended to replace or override the requirements of those bridge design standards. Rather, it is intended to
provide an awareness of issues to be considered in bridge design and bridge management in order that
those involved in using the Standards will be better equipped to apply and interpret them to achieve the best
design outcomes.
It is intended that the Guide will complement AS 5100 and the NZ Manual, and that the publications will have
consistent technological bases. This applies not only to the design of bridges, but also to the assumptions
made in the bridge design process; for example, to the effectiveness of site investigations and geotechnical
investigations and to the choice of design parameters as a result of those investigations, and also to:
• the quality control exercised in fabrication
• site supervision
• the control of unavoidable imperfections
• qualifications, experience and skill of all personnel involved
• documentation of design assumptions to ensure control over the conditions of use of the structure over its
life
• the application of statistical methods and documentation of construction process and material properties.
• The AGBT is written on the basis that management control and supervision by experienced professional
engineers shall be undertaken at all stages of design and construction to prevent the occurrence of gross
errors.
2.1 Scope of AS 5100
The scope of AS 5100 includes the design of bridges to support loads from: road traffic, rail traffic, tramways
and pedestrians, separately or in combinations. It also applies to other structures that are required on road
and railway routes, including road signs and lighting structures, noise barriers and protection screens,
retaining structures, deflection walls and crash walls, culverts and structural components related to tunnels,
and, where applicable, structures built over, or adjacent to, roads or railways.
The load capacity assessment and design for the strengthening and rehabilitation of existing bridges is also
addressed in the scope of AS 5100.
AS 5100 applies to bridges with spans of up to 100 metres. For bridges with longer spans, rail bridges for
train speeds greater than 160 km/h, or unusual or more complex structures, as well as wave action on
bridges, the provisions of AS 5100 shall be supplemented by other appropriate Standards and specialist
technical literature for loading and strength requirements. Where bridges are to be constructed from
materials other than those covered specifically by AS 5100, reference shall be made to other appropriate
Standards and current technical literature for material-specific performance durability requirements.

2.2 Scope of NZ Transport Agency Bridge Manual
The NZ Transport Agency Bridge Manual (NZ Transport Agency 2016a) sets out the criteria for the design
and evaluation of bridges, culverts, stock underpasses and subways and the design of earthworks and
retaining structures. The Manual is a companion document to the overarching Highway Structures Design
Guide (NZ Transport Agency 2016b), which specifies general and specific design criteria for all highway
structures. The Manual covers those bridges carrying road and/or pedestrian traffic, in which the main
supporting members are of reinforced or prestressed concrete, structural steel, timber or aluminium, utilising
beam or arch action, and spanning up to 100 metres. It includes the design of major culverts, stock
underpasses and pedestrian subways, slopes, embankment and cuttings, retaining wall systems such as
gravity walls, cantilever walls, mechanically-stabilised earth walls and anchored walls. It does not include
cable supported structures or bridges subject to railway loadings, nor does it specifically cover all forms of
other highway structures such as sign gantries, sign supports, lighting supports, noise walls and fences.
These other highway structures are covered in NZ Transport Agency (2016b).
Where appropriate, New Zealand, Australian and other recognised international standards are referenced for
the specification of design actions, materials design, design of elements of the structure, and the design of
particular types of structure. Progressively, as amendments take place over time, harmonisation with
Australian practice is being sought where appropriate.
2.3 Confirmation of Design Parameters by the Road Agency
In the application of AS 5100 to the procurement of bridges, a number of Clauses nominate that the
requirements of those Clauses shall be confirmed as accepted by the relevant agency or owner of a bridge
or associated structure before the design process commences. The AGBT Part 4: Design Procurement and
Concept Design is also intended to provide assistance to authorities/owners in determining these
requirements.
The processes for design, construction, maintenance and use of bridges shall be monitored and reviewed by
bridge owners/authorities to ensure compliance with all relevant legislation and regulations.

3. Influences on the Evolution of Australian and New

Zealand Bridges
The evolution of bridge design and construction in Australia and New Zealand, as in the world at large, has
been driven by the continual need to build more economically. It has been enabled by developments in
materials, improvements in construction techniques, the development of new structural forms, and progress
in structural analysis and the theory of strength of materials.
Prior to the 18th century, timber and masonry were the only materials available for the construction of major
bridges. Timber bridges suffered from the deterioration of the material, although some early covered timber
bridges still exist in their original form, the most notable being the Kapellbrücke (Chapel Bridge) in Lucerne,
Switzerland, dating from 1333. Masonry arch bridges reached a pinnacle of achievement during the Roman
Empire, and many fine examples are still in existence throughout Europe. However, by the time of the first
European settlement in Australia the industrial revolution had begun in England, and this provided a new
material for bridge builders, and heralded an exciting new era in bridge construction.
Following European settlement, the first bridges in Australia and New Zealand were timber structures. As
the settlements became established there was a need for more permanent river crossings, and the first
masonry bridges were constructed. The oldest extant bridge in Australia is the masonry arch bridge across
the Coal River at Richmond in Tasmania, constructed in 1825 (O’Connor 1985). During the 1830s, David
Lennox constructed a number of masonry arch bridges in New South Wales, many of which still survive
(Pearson, Best & Fraser 1987). Masonry bridges were labour-intensive, however, and timber remained the
most popular bridging material throughout the 19th Century. During the second half of the 19th Century, iron
and steel bridges became increasingly popular for major structures in New South Wales and Victoria.
Initially these bridges were imported from Britain, often as complete structures ready for erection. The first
concrete bridges were constructed by the end of the 19th Century. This marked the end of masonry as a
bridging material, and heralding an era of reinforced and prestressed concrete bridges that has prevailed up
to present times.
In the sections that follow, the evolution of steel and concrete bridges is discussed. Between them these
materials account for the vast majority of new bridge designs in Australasia. As such, an understanding of
the history of the development of these materials is valuable to the designers of new bridges, if for no other
reason than to learn from the mistakes, as well as the achievements, of the past. Timber bridges are
discussed briefly, in recognition of their importance in the bridge inventories in parts of Australasia. Refer to
Section 10 of AGBT Part 2: Materials for a further discussion on masonry bridges.
3.1 Timber Bridges in Australia
Timber bridge engineering in the 19th Century was taken to a new level of achievement in the USA, driven by
the need for cheap bridges to expand the rail network. It was during this period that many well-known timber
truss forms were developed in the USA, including the Howe, Pratt, Fink and Bow trusses. These trusses
typically comprised timber compression members and iron tension members.
In Australia, the American truss forms were adopted for bridge crossings where the span was too great for
timber logs. However, the unique properties of Australia’s hardwood timbers and the ingenuity of its
engineers lead to some important adaptations of the timber truss bridge form.
Percy Allan, an engineer with the New South Wales Public Works Department, was responsible for the
design of some 550 bridges, and the Allan timber truss which he developed has been recognised as one of
the notable achievements in Australian bridge engineering. The Allan timber truss allowed for ease of
construction, ease of maintenance by the ready replacement of timbers, and detailing to avoid moisture traps
that promoted rot.

Concerns over the cost of ongoing maintenance, as well as difficulties coping with increasing design loads,
has meant that the design and construction of new timber bridges has all but ceased. However, timber
bridges remain an important part of the bridge inventory in parts of Australasia. The Queensland
Department of Transport and Main Roads (TMR), for example, has over 300 timber bridges in service.
Inspection, maintenance and rating procedures have been developed to deal with these timber bridges.
Readers are referred to Roads and Traffic Authority (RTA) (2000) for further reading on the historical
development of timber girder bridges in NSW. Readers are also referred to Section 2 of the AGBT Part 3:
Typical Superstructures, Substructures and Components for further details on structural forms and typical
components of timber bridges.
3.2 The Age of Iron and Steel
In 1779, soon after the beginning of the Industrial Revolution, a cast iron bridge was constructed across the
River Severn at Coalbrookdale in England (Figure 3.1). This bridge is generally recognised as marking the
transition from timber and masonry to steel as the principal bridge building material. The 30 metre span
bridge, designed by Arthur Darby, was a cast iron arch, thereby utilising the best properties of the cast iron
material, which was weak in tension. Many more cast iron arch bridges were built subsequent to
Coalbrookdale, the largest span being John Rennie’s 73 metre span bridge over the Thames, built in 1819.
Figure 3.1: Iron Bridge, Coalbrookdale
While the cast iron arch bridge introduced a new material, the structural form was based on a tradition of
timber truss-arch construction. It took another 100 years before structural forms were fully developed to suit
the improvement in properties from cast iron to wrought iron to steel.
Thomas Telford recognised the superior properties of wrought iron, and used the material for the rigid links of
the suspension cables on the Menai Suspension Bridge, completed in 1826. In the same year Telford
completed the Conway suspension bridge, again with wrought iron links. These bridges firmly established
the suspension bridge form in modern bridge engineering. They also demonstrated the problems with deck
flexibility, with the Menai Bridge suffering repeated storm damage. In 1836 the Brighton Chain Suspension
Pier in England was destroyed due to severe wind damage, demonstrating again the flexibility of suspension
bridges, an issue that would not be fully understood until after the collapse of the Tacoma Narrows
suspension bridge in 1942.

A major step forward in the construction of steel bridges was the development of riveting machines by
William Fairbairn during the first half of the 19th Century. By the middle of the 19th Century, wrought iron,
which had superior tensile properties, was replacing cast iron as the material of choice. Steel truss bridges
constructed using wrought iron plates and rolled sections (predominantly angles) became common for larger
spans. By the second half of the 19th Century wrought iron beams comprising plate webs and flanges
connected with riveted angle sections were commonly used for shorter spans, and as secondary members in
larger-span bridges.
Bridges were required for the ever-expanding rail network, and flexible suspension bridges were not the
answer. William Fairburn and Robert Stephenson extended the use of wrought iron in spectacular fashion to
design the Brittania (1850) and Conway (1849) tubular bridges. The span of the Brittania Bridge was
140 metres – prior to these bridges the longest span for a wrought iron bridge had been 10 metres. These
bridges introduced steel plate girders into bridge construction, and set an example for plate and box girder
bridge construction that would not be further developed until the 20th Century.
The second half of the 19th Century saw great progress in iron and steel bridges. Spectacular wrought iron
truss and truss-arch bridges were constructed across Europe. The Grandfey Viaduct near Fribourg in
Switzerland (1862) was the first true modern trussed girder with a correct arrangement of compression
members. This bridge, with seven 49 metre spans, was constructed by launching the girder from one end.
In 1860 Karl Culmann, a Professor at the ETH (Swiss Federal Institute of Technology) in Zurich, published
the graphical method of structural analysis, which enabled proper analysis of trusses to be undertaken for
the first time. Gustave Eiffel, builder of the Eiffel Tower in Paris, designed and built some magnificent steel
bridges, both as trusses and truss-arches. Probably his most famous bridge is the Viaduc de Garabit, built in
France in 1884 with a span of 165 metres. Eiffel was also the first to fully detail his steelwork design to
include every element and rivet.
The Tay Bridge in Scotland was a wrought iron truss bridge with 75 metre spans on cast iron columns. In
1879, one year after opening, the bridge collapsed in a storm. This was the greatest ever failure of an iron
bridge. The collapse of the Tay Bridge caused a reassessment of wind pressure used for the design of
bridges; it also marked the end of the great era of wrought iron bridges.
Steel was developed and gradually replaced wrought iron during the second half of the 19th Century. Its use
in England was first approved in 1877. However, steel had been used before this date in the construction of
the St Louis Bridge, of 158 metre span, over the Mississippi River, which was completed in 1874 (Figure
3.2). The St Louis Bridge, which was a truss-arch bridge, was the first bridge constructed by JB Eads, and it
was a world record span for a truss-arch bridge.
Approval for the use of steel in the UK was received just in time for the construction of another landmark
Scottish Bridge, the Forth Rail Bridge, which was completed in 1890. It was a cantilever truss bridge with a
span of 520 metres. A wind pressure of 2.7 kPa was used in the design of the bridge, no doubt as a reaction
to the collapse of the Tay Bridge. In 1868 the German bridge engineer Heinrich Gerber had patented the
introduction of hinges into continuous beam bridges to overcome the problems caused by support
settlements. Such structures became known as Gerber beams. The cantilever bridge is a particular
example of the Gerber beam, having advantages of structural determinacy, structural efficiency and
construction expediency.
Suspension bridge design and construction developed during the second half of the 19th Century, although it
would take a further 50 years for this form of construction to establish itself as the dominant form for
long-span bridge construction. Roebling’s famous Brooklyn Bridge was completed in 1883. The bridge
spans the East river between Brooklyn and Manhattan and stretches for a length of 5989 ft, about 1.8 km.
The span between the large towers measures 1595.5 ft (486 meters). This made the Brooklyn Bridge the
world's largest suspension bridge until the completion of the Forth Bridge seven years later.

Figure 3.2: St Louis Bridge under construction
Source: Woodward, CM (1881), reproduced courtesy of the Institution of Civil Engineers, UK.
Along with the improvement in steel for bridge building, the second half of the 19th Century also saw big
improvements in construction technology. Caissons and the use of compressed air were introduced for
excavating bridge foundations. Construction of a steel arch bridge by cantilevering from the abutments was
carried out for the first time in 1874 with the construction of the St Louis Bridge.
Prior to World War 1, most steel for bridges was imported into Australia from the UK, USA, Belgium, France
and Germany. Local steelmaking had begun with the Fitzroy Ironworks at Mittagong, NSW, in 1848. Other
blast furnaces existed at Mt Jagged, South Australia, (1874) Lal Lal near Ballarat (1875), Ilfracombe on the
Tamar in Tasmania (1875), a new plant at Lithgow (1875), Mittagong (1876) and Redbill Point, also on the
Tamar (1878). However, the combined output of these furnaces was insignificant when compared to the
steel quantity required for a medium-size steel bridge. With the opening of the BHP Steelworks in
Newcastle, Australia became an exporter of steel products from 1916, although structural steel was still
imported for special work such as the construction of the Sydney Harbour Bridge. Many early metal bridges
in Australia were built using imported prefabricated ironwork. In this context, it is believed that the famous
English engineer IK Brunel supervised the fabrication in Britain of a number of Australian bridges. The
Menangle Bridge in New South Wales, which is still in service carrying the main south rail line, is a wrought
iron bridge designed and constructed in England and erected in 1863. Originally with 50 metre spans, the
spans were halved by the construction of intermediate piers. The first bridge over the Murray River was built
at Murray Bridge, South Australia, in 1879. The wrought iron truss bridge with cast iron piers was designed
and manufactured in England.
Teaching of bridge engineering in Australia moved forward with the appointment of the first Professors of
Engineering at Melbourne University (WC Kernot in 1883) and the University of Sydney (WH Warren in
1884). In 1898 Kernot published the first edition of his book ‘On some common errors in iron bridge design’
which discussed the design and detailing of iron girder and truss bridges.
Readers are referred to Section 4 of AGBT Part 3: Typical Superstructures, Substructures and Components
for further details.

3.3 Steel Truss and Truss-arch Bridges
The development of steel with its improved properties allowed the size of structures to increase. The first
decades of the 20th century were the pinnacle for steel truss-arch and cantilever bridge construction.
At the turn of the century the Forth Bridge held the record for the world’s longest span; however, the design
and construction of steel truss-arch bridges was challenging the cantilever form for supremacy. The Niagara
Arch Bridge, with a span of 256 metres was completed in 1897. In America, the famous bridge engineer
Gustav Lindenthal designed the Hell Gate Bridge, with a span of 298 metres. This bridge was opened in
1916.
The form of the Hell Gate Bridge is very similar to Australia’s most famous structure. The Sydney Harbour
Bridge was the second longest span arch bridge on its completion in 1932, and it is currently the world’s fifth
longest span arch bridge. The Sydney Harbour Bridge was very much the work of Dr J. Bradfield, the Chief
Engineer of the New South Wales Government. The design, however, owed much to the work of English
consulting engineer Ralph Freeman. The design and construction of the Sydney Harbour Bridge provided a
great impetus to bridge design and construction in Australia, requiring the development of design and
construction skills that were not previously available in the country. The boost that it gave to Australia’s
bridge expertise is evidenced by the fact that the Story Bridge in Brisbane, completed eight years later, was
designed and constructed without the British input that characterised the Sydney Harbour Bridge.
The Sydney Harbour Bridge was beaten for the title of the world’s longest span arch bridge by the Bayonne
Bridge, which was completed one year earlier. It has a span of 504 metres, just 0.6 m longer than the span
of the Sydney Harbour Bridge. This remained the longest steel arch bridge in the world until the New River
Bridge was constructed in the USA in 1977 with a span of 518 metres. Recently two Chinese steel arch
bridges, the Lupu and the Chaotianmen, have been constructed with spans of 550 metres and 552 metres
respectively.
After the Forth Bridge, the next major cantilever bridge to be built was the Queensboro Bridge in New York,
which was completed in 1908 with a span of 360 metres. During this same period construction commenced
on the ill-fated Quebec Bridge in Canada, with a span of 549 metres. This was the last of the cantilever steel
bridges to hold the longest bridge span record. During the erection of the suspended span (by cantilevering
from the cantilever arm) web buckling developed in some lower chord plates of the cantilever arm near the
support, resulting in the collapse of the bridge. The bridge was rebuilt to a new design; however, in 1916
while the suspended span was being erected (this time by lifting from a pontoon on the river) the cantilever
span collapsed. This time it was determined that the design was sound and that the problem was related to
erection issues. The cantilever span was rebuilt, and the bridge was finally opened in 1919.
Brisbane’s Story Bridge, completed in 1940, is Australia’s largest cantilever bridge with a span of
282 metres. After retiring from the NSW Public Works Department, Bradfield arrived in Brisbane in 1933 and
was appointed as the consulting engineer for the Story Bridge. The bridge was built by a Queensland
consortium of MR Hornibrook and Evans Deakin.
In 1937 Bradfield visited Auckland and subsequently developed a proposal for a 914 metre span suspension
bridge across Waitemata Harbour. Bradfield’s proposal was not progressed, and it was not until 1959 that a
steel truss bridge, with a maximum span of 244 metres, was built across the harbour. In 1969 the four lane
bridge was increased to eight lanes with the addition of the ‘Nippon clip-ons’ – two-lane steel box girders that
were designed and manufactured in Japan and added to each side.
The Hawkesbury River Road Bridge, constructed by the NSW Department of Main Roads and completed in
1945, has two steel truss spans of 134 metres. However, the most significant aspect of this bridge is the
foundation construction, which was an outstanding example of Australian bridge construction under very
difficult conditions. Under the approach spans, one of the caissons extends to a final depth of 73 metres
below the water level. This was the second deepest bridge foundation constructed in the world up to that
time (Office of Environment and Heritage 2017).

Steel truss bridges are no longer commonly constructed because of the high costs of fabrication, but also
because statically determinant bridges do not have redundancy to redistribute the loads in case of overload
or local failure, and thereby avoid collapse of the entire structure. This was vividly illustrated with the
collapse of the I-35W Mississippi River bridge in 2007 (Section 4.2). The bridge, constructed in 1967, was
an eight-lane steel truss arch bridge. Thirteen people were killed in the collapse, and 145 were injured. A
design flaw related to gusset plates has been cited as the cause of the collapse.
Readers are referred to to Section 4.3 of AGBT Part 3: Typical Superstructures, Substructures and
Components for further details of steel truss bridges.
3.4 Steel Girder Bridges
After the pioneering wrought iron bridges by William Fairburn and Robert Stephenson in the
mid-19th Century, steel plate and box girder bridges were not prominent in major bridge construction,
possibly because of the relatively large quantities of material that were required compared to truss forms.
However, the development of the road system required bridges of medium span, and often of minimum
depth in order to limit the earthworks required. The Elbe Bridge constructed in Germany in 1936 is credited
with sparking a new interest in steel plate girder bridges. Also in Germany, major rebuilding programs after
World War II required bridges that were quick to fabricate, and this lead to the development of the steel box
girder bridge. However, as history tells us, the design and construction of these complex structural forms
preceded a complete understanding of their behaviour, resulting in a series of major collapses of steel box
girder bridges in the early 1970s. The collapses were over the Danube at Vienna, at Milford Haven in Wales,
over the Rhine, and the West Gate Bridge in Australia, where a 1200 ton section of deck collapsed with the
loss of 35 lives. These collapses lead to a halt in construction of box girder bridges until design rules could
be further developed. In 1973 the ‘Committee of Inquiry into the Basis of Design and Method of Erection of
Steel Box Girder Bridges’ published what became known as the Merrison Rules (Department of the
Environment 1973). These have since been written into codes of practice for steel bridge design, and have
a major influence on steel bridge design to this day.
Welded steel bridges began to appear around 1930, with the first in Britain built in 1931. Welding offered
greater economy and utilisation of the strength of the joined components, because unlike riveting which it
replaced, it was possible to have no loss of capacity at the joints. Australia was quick to adopt the
technology, and in 1931 the Country Roads Board in Victoria constructed McKillop’s Bridge over the Snowy
River as an electrically-welded continuous deck steel bridge claimed to be one of the longest welded bridges
in the world at the time. The University Footbridge across the Torrens River in Adelaide (Figure 3.3) was
constructed in 1937 as South Australia’s first welded steel bridge (Altman et al. 1999). Brittle fracture of
welded steel bridges was an issue of concern. Fourteen welded steel bridges failed in Belgium between
1938 and 1950.
In 1961 a new road crossing of the Yarra River in Melbourne, known as Kings Bridge, was opened to traffic.
The typical bridge section comprised four welded plate girders with a concrete deck slab. Fifteen months
after opening, on a cold July morning, the four girders of one span fractured under the weight of a single
semi-trailer, and the span dropped 300 mm onto a concrete wall below. The subsequent Royal Commission
found that brittle fracture of the steel girders was due to the brittle nature of the steel itself. This incident led
to changes in steel specification, welding techniques, and probably to a (short term) preference for bolting
over welding.
Readers are referred to Section 4.2 of AGBT Part 3: Typical Superstructures, Substructures and
Components for further details of steel girder bridges.

Figure 3.3: Opening of the welded construction University Footbridge across the Torrens, 1937
Source: Courtesy of University of Adelaide Archives.
3.5 Suspension Bridges
The 20th century saw a succession of magnificent suspension bridges constructed, each creating a new span
record. During the first half of the 20th century the USA was the home of suspension bridge development.
Following Roebling’s Brooklyn Bridge, with a span of 486 metres, the next great suspension bridge was the
George Washington (1067 metres) in 1931). This record span was subsequently bettered by the Golden
Gate bridge in San Francisco (1280 metres, 1937), the Verrazano-Narrows bridge in New York
(1298 metres, 1964), the Humber bridge in Kingston Upon Hull, England (1410 metres, 1981) and the
Akashi-Kaikyo bridge in Japan (1991 m, 1998). As Australia does not have any significant suspension
bridges, these will not be discussed further in this Guide, other than to mention two suspension bridge
failures that had major influences on bridge design.
The collapse in 1942 of the Tacoma Narrows Bridge under steady winds of moderate strength led to
extensive research and consequent understanding of the dynamic behaviour of suspension bridges, and the
need for detailed aerodynamic design of wind sensitive bridges. Subsequent suspension bridges, beginning
with the first Severn Bridge in the United Kingdom, have been designed with particular attention to the
aerodynamic performance of the deck cross section.
On 15 December 1967, the Silver Bridge across the Ohio River collapsed while it was heavily loaded with
traffic, resulting in 46 deaths. The bridge was an eyebar chain suspension bridge built in 1928. However,
unlike the eyebar suspension bridges of Telford and Brunel that employed multiple bars of wrought iron, the
Silver Bridge had only two bars, which were of high strength steel. The cause of the collapse was identified
as the failure of a single eye-bar due to a small defect only 2.5 mm deep. The collapse of the Silver Bridge
reminded bridge designers of the need to have redundancy in their structures.
for further details of suspension bridges.

3.6 Cable Stay Bridges
The modern cable stay bridge form is generally recognised as having developed in Germany in the decades
after World War II. The first large cable stay bridge was built at Strömsund in Sweden, to the design of
German engineer Franz Dischinger. It has a 182 metre span, having two cables, in two planes. The
development of cable stay bridges owes much to the German engineers Leonhardt, Walter and Schlaich.
The use of a torsionally stiff box girder deck, whether in concrete or steel, enabled the bridges to be built with
one central plane of cables, allowing more efficient and more aesthetically pleasing bridges to be
constructed. The economic span of cable stay bridges has steadily increased to the extent that the current
longest span cable stay bridge, the Russky Bridge in Russia, has a span of 1104 metres.
The first modern cable stay bridge in Australia was the Batman Bridge, constructed across the Tamar River
in Tasmania in 1968. The longest span cable stay bridge is the Anzac Bridge (Figure 3.4) over Sydney
Harbour, which was designed by the Roads and Traffic Authority, New South Wales. It opened in 1995 with
a main span of 345 metres. Somewhat like the design of the Sydney Harbour Bridge before it, the design of
this bridge by the RTA provided an opportunity for the skill development of Australian bridge engineers.
Those skills have since been exercised by Australian engineers in the design of cable stay bridges overseas.
The West Gate Bridge in Victoria has a main cable stay span of 336 metres.
Figure 3.4: Anzac Bridge, Australia’s longest span cable stayed bridge
Source: RTA NSW (n.d.).
for further details of cable-stayed bridges.

3.7 The Rise of Concrete Bridges
Today concrete is the dominant structural material for bridge construction in Australia. Reinforced concrete,
patented by Joseph Monier in 1867, was first used in bridge construction at the end of the 19th Century,
initially with the construction of arch bridges, where the concrete material was a substitute for stone masonry.
However, within a short period the properties of reinforced concrete came to be better utilised, and bridges
began to be constructed with reinforced concrete beams. The theoretical basis for calculating the strength of
reinforced concrete beams was developed in Germany during this period, and further progressed by the
French engineer Francois Hennebique whose designs included the 55 metre span Ourthe Bridge in Belgium
in 1904.
In 1902 the German engineer Emil Morsch published his theory on truss models for reinforced concrete, a
theory that is still in use today. During the 1930s the Swiss engineer Robert Maillart designed and built some
of the most beautiful bridges ever constructed, using deck stiffened concrete arches. These bridges have
inspired and influenced generations of engineers since. During the same period Eugene Freyssinet
developed the concept of prestressing the reinforcing steel, and in 1930 he built the Plougastel Bridge in
France, the first major prestressed concrete bridge to be constructed. In the second half of the 20th Century
prestressed concrete established its position as the most popular material for bridge construction.
Various methods of prestressed concrete bridge construction were developed to deal with the challenges of
long spans and difficult terrain. In Australia, the Gladesville Arch Bridge across Sydney Harbour combined
the age-old technique of arch construction with the modern material of prestressed concrete. The bridge,
with a span of 305 metres, was constructed by assembling precast segmental arch sections on falsework
and prestressing the segments to form the arch.
Freyssinet always insisted on full prestressing, i.e. no tensile stress under service loads. In 1945 PW Abeles
published a paper on the concept of partial prestressing, which gradually became accepted over the
following decades and resulted in economy in bridge construction.
Concrete box girder bridges, either cast in situ or precast segmental, were developed in the 1950s and
1960s as appropriate motorway bridges. The concrete box girder could be cast in place using travelling
formwork, or it could be precast in segments. The bridges could be erected as balanced cantilevers from a
pier, or they could be incrementally launched across the top of the piers. Jean Muller, a French engineer,
was representing Freyssinet’s firm in New York in 1952 when he designed the first match-cast
glue-segmental box girder for the Shelton Road Bridge. This form of construction became very popular in
the USA and elsewhere around the world. In 1978 Muller formed the company Figg & Muller Engineers, who
were responsible for the design and construction of some of the great concrete box girder bridges including
Florida Keys and the Sunshine Skyway. Muller then went on to form the consultancy Jean Muller
International. Through these various stages of his career Jean Muller was instrumental in developing new
ways to construct bridges, including match cast segmental, the first launching gantries, external prestressing
for box girders, and precast segmental construction for cable stay bridges. These are techniques used by
bridge designers and constructors in Australia today.
Brisbane’s Sir Leo Hielscher Bridges (also known as the Gateway Bridges) was constructed in 1986 and
duplicated in 2010. It has a 260 metre main span, which was the longest spanning cantilever concrete box
girder bridge in the world at that time. It is currently the seventh longest prestressed concrete girder bridge.
The first few reinforced concrete bridges built in Australia were reinforced with whatever steel materials were
available at that time, including steel rails and reused mine cables. The most notable of these early bridges
is the 1896 Lamington Bridge at Maryborough in Queensland, which has eleven 16 metre spans. The
Monier system of reinforced concrete was introduced to Australia by Carter Gummow & Co. in Sydney, who
obtained the Australian rights to the patent from the German firm of Wayss & Freytag (who had bought
Monier’s patent in 1886 and developed the technology). Carter Gummow & Co constructed the Annandale
sewer aqueducts in Sydney (Figure 3.5) using Monier arches in 1896 (Fraser 1985). This technology
transfer of reinforced concrete to Australia was due to William Baltzer, an engineer who trained in Germany
and worked with the NSW Public Works Department. In the early 1890s Baltzer joined Carter Gummow &
Co. as chief engineer. With his German background Baltzer was able to access the German technical
journals which described the new technology.

The momentum for the development of reinforced concrete in Australia soon switched to Melbourne,
however, when the partnership of John (later Sir John) Monash1 and Joshua T Noble Anderson negotiated
with Carter Gummow & Co. for the Monier rights in Victoria, South Australia and Tasmania. In Melbourne
the Anderson Street Bridge across the Yarra was constructed by Carter Gummow & Co. in 1899, with
Monash and Anderson acting as their local agents. The bridge had a span of 30 metres, which was a large
span for a reinforced concrete bridge at that time. Monash & Anderson went on to construct a further
17 Monier arch bridges in Victoria between 1900 and 1905. At that point the partnership was dissolved, with
Anderson moving to New Zealand.
Around the same time, Monash became aware of the development in Europe of reinforced concrete girder
bridges, and he constructed Australia’s first such bridge in Ballarat, Victoria, in 1904. The bridge was not a
success, suffering unacceptable shear cracking. Monash conducted original research at the University of
Melbourne into shear in reinforced concrete. This was at a time when the theories of reinforced concrete
were being developed in Europe. From that initial setback, Monash went on to construct about 70 reinforced
concrete girder bridges in Victoria and South Australia prior to leaving Australia to serve in World War I.
Many of those bridges are still in service (Holgate n.d.). Soon after the Country Roads Board was formed in
Victoria in 1913 it prepared standard designs for reinforced concrete bridges. These were largely based on
the Monash bridges, and so the pioneering work of Monash influenced the design of bridges, certainly in
Victoria but also throughout Australia, for much of the early part of the 20th Century.
Figure 3.5: Annandale sewer aqueduct, the oldest extant use of Monier Concrete in Australia
Source: Holgate (n.d.).
1 A brief biography of Sir John Monash (‘Leading the Way: Sir John Monash’) can be found at:
http://www.adm.monash.edu.au/records-archives/exhibitions/sirjohn/engineer/.

After the Second World War prestressed concrete started to appear gradually in Australia, with the earliest
prestressed concrete bridges being constructed in the mid- to late-1950s. At the same time the precasting of
concrete beams began – first with reinforced concrete beams and then with prestressed concrete beams.
Prestressed planks, U-slabs and I-beams became the standard components for short and medium span
bridge construction in Australia from the 1960s, a practice that continues to today. The precast prestressed
Super Tee beam was first introduced by VicRoads in the early 1990s, initially intended for spans up to
19 metres. The construction efficiency that the new beam offered in comparison to the I-beam saw it gain
rapid acceptance, and today the Super Tee beam is the most common form of bridge construction for spans
up to 40 metres. It is also gaining increasing popularity throughout parts of South East Asia.
In 1985 the Ynys-y-gwas Bridge in South Wales collapsed due to corrosion of the post-tensioning cables.
This, and similar problems detected with a number of other post-tensioned bridges in the UK, caused the UK
Department of Transport to place a moratorium on the use of internal post tensioning. The moratorium was
lifted in September 1996 after the publication of grouting guidance notes in Concrete Society Technical
Report 4.7 on durable post-tensioned concrete bridges (Concrete Society 2002). While the climatic
conditions and associated road and bridge maintenance practices in Australia do not lead to corrosion at the
same rate, the reassessment of grouting practices both in the UK and in the USA has had an influence on
the design and construction of post-tensioned bridges in Australia.
Readers are referedr to Sections 5 and 6 of AGBT Part 3: Typical Superstructures, Substructures and
Components for further details of concrete and prestressed concrete bridges.
Developments in concrete materials have led to concretes with higher strength and improved durability.
When concrete was first used for bridge construction, materials were batched by volume on site, and the key
role of water in the mix was not well understood. The advent of specialised concrete batching plants with
sophisticated weigh batching equipment, coupled with the advances in concrete technology, have led to
great improvements in the properties and the quality control of concrete. At the end of the 19th Century, slag
and fly ash were used as supplementary cementitious materials in concrete (Anderson 1899). In the latter
part of the 20th Century supplementary cementitious materials were ‘rediscovered’ and applied to concrete
with the benefit of a much greater understanding of concrete technology. This has enabled the production of
concretes with improved placing and handling characteristics, and with much reduced permeability, and
therefore increased protection to the reinforcing steel.
Concrete bridges, probably more than steel bridges, have benefited from improvements in construction
equipment. Pumps for transporting and placing concrete have reduced the costs of concrete construction.
Increases in the lifting capacity of both mobile and fixed cranes have meant that larger components can be
precast and incorporated into the works. Jacking equipment has increased in capacity while reducing in
size, thereby enabling techniques including prestressing and incremental launching to be developed and
improved.
Recent developments in the concrete materials and concrete construction have seen the applications of a
number of special types of concretes, including self-compacting concrete, ultra-high performance concrete,
reactive powder concrete and geopolymer concrete. Steel and polymer fibres have been used as a
supplementary material in reinforced and prestressed concrete components to inhibit cracking, improve the
resistance to impact or dynamic loading, and improve material integration. As a reinforcing material, fibre
reinforced polymer (FRP) reinforcement has been used to provide a practical and economic alternative to
conventional steel reinforcement in concrete structures where corrosion resistance and electromagnetic
resistance are required, such as in bridges within a marine environment. FRP has also been used in various
bridge applications such as complete FRP structures, FRP replacement components and FRP strengthening
of existing structures.
Readers are referred to AGBT Part 2: Materials for further details of these recent developments.

3.8 Bridge Aesthetics and Urban Design
The potential for bridges to be objects of great beauty has been recognised probably since the earliest times.
There are countless examples of ancient arch bridges well recognised for their contribution to the landscape.
Perhaps these beautiful bridges occurred by chance or perhaps as a result of the work of a particularly gifted
bridge designer. With the increasing specialisation that has occurred as technology has developed, bridge
aesthetics, and the integration of the bridge with the surrounding urban or rural landscape is now
acknowledged as a specialist activity in its own right. Increasingly bridge designs are being awarded not on
the basis of technical excellence or functional performance (which are both taken as ‘givens’), but on the
basis of the bridge aesthetic.
An awareness of bridge aesthetics and the contribution of the bridge to the surrounds must be part of any
bridge design process. In Australia the Roads and Maritime Services (Roads and Maritime) has published
Bridge Aesthetics: Design Guidelines to Improve the Appearance of Bridges in NSW (Roads and
Maritime 2012).
Readers are referred to Appendix C of AGBT Part 4: Design Procurement and Concept Design for a list of
references for bridge aesthetics.
3.9 Other Singular Events of Influence
Australia has had its share of bridge failures. The West Gate bridge disaster has been mentioned, as has
the Kings Bridge collapse. International bridge failures have also, of course, influenced Australian bridge
design and construction, and in this context the collapse of a number of international bridges has been
discussed. However, there is no doubt that bridge failures close to home have the greatest impact and
influence on Australian practice. Two incidents will be mentioned here.
On 5 January 1975 the freighter Lake Illawarra collided with two pylons of the Tasman Bridge across the
Derwent River in Hobart. Two pylons and three sections of bridge collapsed, the freighter sank, and four
cars drove into the river. Twelve lives were lost and the city of Hobart was split in two. Two years later, on
18 January 1977, a passenger train passing underneath the Granville Railway Bridge in Sydney derailed and
collided with the pylons. A section of the bridge collapsed onto the passenger train, resulting in 83 deaths
and 210 injuries. These incidents have altered the way in which bridge concepts are developed, with much
greater consideration being given to the location of piers, and the risk of impact.
3.10 The Development of the Bridge Design Standard
3.10.1 NAASRA Bridge Design Code
The NAASRA Bridge Design Code was first issued in 1953 by the National Association of Australian State
Road Authorities (NAASRA). This design code was based on a working stress format with many of the
provisions closely following the American Association of State Highway Officials (AASHO) Bridge design
specifications (see, for example, AASHO 1953).
This code underwent a number of revisions (1958, 1965 and 1970) until it was eventually replaced by the
1976 NAASRA Bridge Design Code.
3.10.2 1992 Austroads Bridge Design Code
Limit states format was presented for the first time in the 1992 Code. This code comprised seven sections,
including:
• Section 1: general
• Section 2: design loads
• Section 3: foundations

• Section 4: bearings and deck joints

• Section 5: concrete
• Section 6: steel
• Section 7: temporary works.
Some of the material in this Code was based on specifications issued by the American Association of State
Highway and Transportation Officials (AASHTO). A commentary was prepared (also for the first time) to
provide background to the code requirements.
3.10.3 HB 77-1996 Australian Bridge Design Code
Sections 1 to 5 of the 1992 Austroads Bridge Design Code were incorporated in this Standards Australia
Handbook. Composite construction was added to Section 6, while Section 7 was developed from previous
documents including the 1976 NAASRA Bridge Design Code, but significantly revised to enable it to be
issued in a Limit States format. A separate railway supplement to Sections 1 to 5 was added.
The Australian Bridge Design Code was the result of a cooperative production and marketing agreement
between Austroads, the Australasian Railway Association and Standards Australia. Similarly, the adoption of
the code as a Standards Australia handbook was to formalise a coordinated approach to the development
and management of the Australian road system.
3.10.4 Standards Australia AS 5100 Bridge Design
The 2004 version of the AS 5100 series represented a revision of the 1996 HB 77 series, Australian Bridge
Design Code, which contained a separate railway supplement to Sections 1 to 5, together with Section 6
Steel and composite construction, and Section 7 Rating. AS 5100-2004 took the requirements of the railway
supplement and incorporated them into Parts 1 to 5, to form integrated documents covering requirements for
both road and rail bridges. In addition, technical material was updated.
The AS 5100-2004 series was updated in 2017 as the AS(AS/NZS) 5100 series, in which Part 6 Steel and
composite construction is a joint part between New Zealand and Australia. Part 8 Rehabilitation and
strengthening of existing bridges and Part 9 Timber were added. Part 8 includes provisions for the design of
FRP strengthening.
In New Zealand, the Bridge Manual was first published in 1956. The current version was published in 2016.
Refer to NZ Transport Agency (2016a) for further information on NZ bridge design standards.
3.11 The Development of Bridge Design Loading
3.11.1 A History of Bridge Design Loads
A summary of the influence on bridge design in Australia would not be complete without a discussion of the
most direct and obvious factor – the design load. Since bridge design loads were first specified at the
beginning of the 20th Century, they have progressively increased to meet the demands of heavier trucks.
A few bridges still in use were built before 1900, when the design load may have been a 16 ton road roller or
a representation of a loaded horse or bullock drawn wagon, or in some fortunate cases, a railway load
configuration. The earliest specified design loads were based on steam traction engines. Prior to 1926 the
Country Roads Board (CRB) specified that bridges be designed for a 15 ton steam traction engine. After
1926 bridges were to be designed for the worst of a uniform or a concentrated loading. The concentrated
loading, still based on a traction engine, was increased to 20 tons for ‘Class AA roads’, 15 tons for Class A
roads and 10 tons for Class B roads. In 1936 the CRB loading was increased again by requiring that bridges
be designed for the uniform and the concentrated loading.

From 1947 bridge design loading was made uniform across Australia, being based upon AASHTO. The
design vehicle was the H20 S16-44 truck (approximately 33 tonnes). This was metricated in 1973 as the
MS18 vehicle.
The next major change came with the introduction of the T44 loading from 1976 (a 44 tonne truck). Then,
from 1999 the SM1600 loading was introduced, marking a step change in the load for which highway bridges
were to be designed.
On average, throughout the 20th Century, legal loads for trucks in Australia increased by approximately 10%
per decade. Since the introduction of limit states design principles in the 1992 Australian Bridge Design
Code, the inherent additional strength available in pre-1992 designs, as a result of the conservative load
factor used for self-weight and dead load, is no longer available. As the design process becomes more
accurate and better defined, there is a need to ensure design loads more accurately reflect future
economically desirable and legally allowed truck loads.
Table 3.1 and Table 3.2 summarise the bridge design loads which have applied to bridges on the road
networks of Australia and New Zealand during different design eras.
Table 3.1: Design eras in Australia
Design era Design load Represents

Pre 1948 Various vehicle configurations plus uniformly Approximately equivalent to 15 to 20 tonne rigid
distributed load (UDL) truck
1948–1976 MS18 (metric equivalent of H20-S16-44) Approximately equivalent to 33 tonne semi-trailer
1976–1992 T44 Approximately equivalent to 47 tonne semi-trailer
1992–2004 T44, but to limit states principles Approximately equivalent to 47 tonne semi-trailer
2004– SM1600 Approximately equivalent to 2 x 75 tonne
semi-trailers, nose to tail
Table 3.2: Design eras in New Zealand
Design era Design load Represents

1933–1943 Traction engine loading, comprising a 46 ton
vehicle with its axles spread over a 77 foot
length, with a UDL of 0.402 ton/ft in front and
behind
1943–1961 H20-S16-44, plus an overload(1) Approximately equivalent to a 33 tonne semi-trailer
1961–1972 H20-S16 T16, plus an overload(1)
1972– HN-HO-72, plus an overload(2)
1 The overload consisted of increasing the truck element by 100% with no concurrent loading in any other lane.
Allowable stresses under dead and live loads were increased to 1.5 x normal allowable stresses.
2 The HO load consists of a HN truck with double the axle loads. In New Zealand the current HN-HO-72 design
loading provides a margin of approximately 15% over the effects of legal truck loads to accommodate future
economically desirable increases in the legal mass limits.
3.11.2 Current Design Traffic Loading and Design Life
The design life required by AS 5100 and by NZ Transport Agency’s Bridge Manual (NZ Transport
Agency 2016a) is 100 years. This design life is a minimum for new structures. Iconic bridges may need to
be designed for a longer period; for example, the duplicate Gateway Bridge in Queensland was specified for
a 300 year design life. The aim of the significant increase in the SM1600 design loading in AS 5100 is to
ensure that bridges designed to this Standard will be competent to carry the anticipated future legally
allowed truck loads throughout the 21st Century.

3.12 Safety in Design and Occupational Health and Safety
Safety in design is mandated by statutory requirements and is incorporated into the design (AS 5100.1).
During the design process, potential hazards and potential risks to persons during construction, future
operation, maintenance and eventual decommissioning of a structure are identified, eliminated or minimised
as part of a risk process. As low as reasonably practicable (ALARP) or so far as is reasonably practicable
(SFAIRP) are examples of risk processes.
As specified by AS 5100.1, the following are documented during the design process:
• hazards identified associated with a design (e.g. hazardous structural features, hazardous construction
materials and hazardous procedures or practices) that might be realised in the construction, operation,
maintenance and decommissioning phases of the project life cycle
• the hazard in terms of the potential risks of injury or harm
• the mitigation controls the designer has developed or utilized to reduce any risk
• aspects of the design where the hazard has been identified but cannot be resolved during the design
phase and needs to be managed during the construction, operation, maintenance and/or
decommissioning phases.
Australian Transport Council (ATC) has required a ‘Safe System’ approach in design of road infrastructure
(Australian Transport Council 2011). This approach is based on the Safe System principles which is ‘a road
safety approach which holds that people will continue to make mistakes and that roads, vehicles and speeds
should be designed to reduce the risk of crashes and to protect people in the event of a crash’.
Provisions for the design of bridges and structures over and under railway lines are particularly more
stringent in the new revision of AS 5100 published in 2017.
Over recent years an increasing emphasis on the safety of workers during both the construction and the
operation and maintenance of bridges has impacted upon the design and construction of bridges.
Consideration of the safety of workers required to work at heights has led to an increasing use of precast
components in bridge construction, and was one the of the driving forces in the rapid adoption of the wide
flange ‘Super Tee’ pretensioned precast beams. The wide flanges of these beams enable a working
platform to be created soon after the beams have been erected, providing a significant safety improvement
over the pretensioned I beams that they have replaced. Consideration of the safety of workers at heights
has also influenced the use of top-down construction of bridges.
Legislation is now in place throughout most of Australasia requiring that designers must ensure, as far as
reasonably practicable that the structure is designed to be safe and without risks to the health of persons
using it as a workplace. For bridges, this means that the designer must consider, and make provision in the
design, for those responsible for maintaining and inspecting the bridge over the design life.
3.13 Future Influences on the Evolution of Australian and New Zealand Bridges
Bridge design and construction will continue to evolve to meet the changing needs of society, and
developments in technology. Global issues of climate change and sustainability will require bridges to use
less non-renewable resources and less energy over their life cycle. Higher standards of safety for workers
and users will continue to be required. Functional performance will be taken as a given, and increasingly the
urban design and aesthetic aspects of bridge design will assume prominence.
Increasingly sophisticated software will mean that bridge designs will be increasingly optimised, leaving little
reserve capacity above that specified to be provided. Real-time continuous monitoring of bridges is
developing as a viable bridge management tool, enabling the health of a bridge to be assessed at any time.
In the future, installation of monitoring may become normal practice in new bridge construction.
Durability planning will become increasingly important, driven by an increasing focus on whole-of-life costs,
particularly for large and/or critical bridges.

Construction plant and equipment will continue to increase in capacity, leading to greater use of larger
components, and a continuation of the trend to off-site construction.
Improvements in materials will continue, such as very high strength and self-compacting concretes, and high
performance steels. Fibre reinforced polymers will mature as a material for the construction of complete
structures, as well as for components such as reinforcing bars and prestressing strands, and of course for
bridge strengthening.

4. Factors Affecting Bridge Performance
4.1 Durability, Robustness and Reliability of Bridges
The requirement for durability, reliability and robustness of bridges over a full 100 year life must be at the
forefront of considerations by bridge owners/agencies for all aspects of bridge procurement and use, from
planning and design, through the construction phase, to maintenance and operations. Limits to bridge
strength can occur because of:
• deterioration of materials related to internal reactions in the concrete and/or severe environmental
conditions
• poor construction practice
• repeated load effects (fatigue)
• severe overload causing cracking, distortion or yield
• flooding, scour and debris loads
• ground movements.
Any compromises or concessions for short-term benefits to others made by the owner’s representatives,
particularly during design and construction, can have far-reaching consequences for the durability, reliability
and robustness of the bridge and for the transfer of risks and costs to the long-term owner and the
community the bridge serves. It is for this reason that there is a level of conservatism, as compared with
general structures, inherent in the design and construction of bridges, a conservatism that should not be
lightly compromised.
The following sections discuss factors that impact on bridge performance, and that should be considered in
the design and management of bridges. Bridge design can influence most of the factors affecting bridge
performance; however, for the purpose of the subsequent sections, these factors are discussed under the
headings of design, materials, components, and construction.
4.2 Design
The greatest opportunity to affect the outcome of a bridge project comes during the stage of concept design.
Every design should include a process of consideration of the structural form, construction methods,
materials, components, and maintenance and operation of a bridge, in order that the best long-term solution,
which may not be the lowest initial cost solution, is selected.
During the detailed design of a bridge, design errors can and do occur. Each design must be scrutinised by
an experienced bridge designer, and the design must be independently checked. The formal process for
review and checking of bridge designs varies with the responsible agencies, with some requiring
independent proof engineering to be undertaken, and others relying upon a less formal (but not necessarily
less rigorous) internal review process. Refer to AGBT Part 4: Design Procurement and Concept Design for
further discussion on the bridge design process.
In 2007 the I-35W Mississippi River Bridge, an eight-lane steel truss arch bridge, collapsed with the loss of
13 lives. Inadequate design of steel gusset plates has been cited as the primary cause of the collapse, an
example of design error during the detailed design phase. However, the collapse of the I-35W bridge also
illustrates how the concept design of a bridge can affect its robustness and reliability. The bridge was a steel
truss bridge and as such was a ‘fracture critical bridge’, meaning that the failure of one primary member
could probably cause collapse of the bridge. Such bridge forms should be avoided, in favour of structural
forms that have multiple load paths, and therefore have greater redundancy.

The collapse of the de la Concorde overpass in Montreal Canada in 2006 was also partly attributed to
design. In this case collapse was caused by the failure of a reinforced concrete halving joint, and was
attributed to poor design detailing, poor construction, and low quality concrete. Cracking at halving joints is
common (Figure 4.1); however, as a result of Australasia’s relatively benign climate and the fact that de-icing
salts are not used, bridge failures as a result of reinforcing corrosion at this location has not been a concern
in Australia. Some road agencies restrict the use of halving joints. Where they are used they must be
designed not only for strength, but also to limit crack widths.
Figure 4.1: Cracking at a halving joint
Source: G Taplin (c2009).
Fortunately, most design problems do not result in the collapse of a bridge, but manifest themselves as, for
example, excessive cracking in concrete structures or deflection in steel structures. The following two
examples illustrate relatively common examples of this.
Prestressed concrete must be designed to distribute the concentrated forces from the prestressing
anchorages into the concrete. Cracking caused by the dispersion of prestress can lead to durability
concerns (Figure 4.2), and must be controlled by the use of an adequate amount of reinforcement.

Figure 4.2: End block cracking in a pretensioned precast beam
If reinforced concrete bridge components are loaded too heavily in flexure, then excessive and unsightly
cracking will result. This can be an indication that the component does not have the reserve of capacity that
would normally be provided in a bridge design. The heavy loading may be a result of a design error, in that
adequate capacity was not provided, or more commonly it is a result of bridges being subjected to loads
heavier than the bridge was designed for, as a result of increases in vehicle weights over time. Figure 4.3
shows a reinforced bridge in the latter category. The flexural cracking in this reinforced ‘U-slab’ bridge is
clearly evident. In this case the problem is compounded by a breakdown of shear connection between the
adjacent precast units, a problem that frequently occurs if the units rely on shear keys for load transfer, and
do not have a topping slab.

Figure 4.3: Flexural cracking in reinforced concrete ‘U-slab’ bridge beams
4.3 Materials
The greatest impact that materials have on bridge performance is when the materials suffer deterioration.
Steel corrosion affects both steel and concrete structures, and concrete bridge structures are also affected
by alkali aggregate reaction and delayed ettringite formation. Concrete in ground or water contact may also
be affected by sulphate attack. These matters are discussed in more detail in Section 4 of AGBT Part 2:
Materials.
Figure 4.4 shows two stages in the development of the corrosion of reinforcing bars. The concrete has
spalled from one beam due to expansion of the corrosion products, while on other beams the concrete has
cracked as the corrosion develops.
Prevention of reinforcement corrosion is addressed by providing adequate cover of good quality concrete,
supplemented where necessary by coatings applied to the concrete surface. Good design and detailing, and
good quality construction (including good compaction and curing) are required to prevent corrosion in
aggressive environments. In extreme cases cathodic protection systems may be required.
Corrosion of structural steelwork is controlled by barrier coatings, zinc coatings applied as galvanising or in a
paint system, or a combination of both. Good detailing is important to minimise opportunities for moisture to
be trapped against the steelwork. In aggressive environments a maintenance program is required for the life
of the structure. Figure 4.5 shows the early stages of corrosion on steel plate girders. Refer to Section 8 of
AGBT Part 2: Materials for information on steel distress mechanisms and defects.

Figure 4.4: Corrosion in reinforced concrete beams
Figure 4.5: Early stages of corrosion of steel plate girders

Timber is a food source for a number of organisms, and provided moisture is present, the deterioration of
timber due to attack by fungus, termites or marine organisms (for timber in water) is guaranteed.
Preservative treatments of timber have been developed, and these can greatly extend the service life. In
addition, shrinkage and splitting of timber due to moisture change can reduce the strength and stiffness of
timber members. Figure 4.6 shows a timber pile that has been affected by marine organism attack.
Refer to Section 9.7 of AGBT Part 2: Materials for further details of timber deterioration mechanisms and
preservative treatments.
Figure 4.6: Marine organism attack of a timber pile
Source: MRWA (n.d.).
The use of fibre reinforced polymer (FRP) in bridge design and construction is relatively new, and the
long-term performance of the material is still being researched. Long-term durability concerns are focussed
on the bond properties of the matrix under long-term exposure to moisture, and to temperature cycles,
particularly if the temperature that the matrix is subjected to approaches the glass transition temperature for
the material.
Figure 4.7 shows slight cracking and separation along the bond line of some fibre reinforced polymer bridge
strengthening. Refer to Section 11.1 of AGBT Part 2: Materials for more details on FRP materials used in
bridge construction.

Figure 4.7: Fibre reinforced polymer used for bridge strengthening
Bridge structures do not usually have fire protection, and so the strength of bridges can be affected if
exposed to a major fire. Figure 4.8 shows the effect of a truck fire on a pretensioned bridge beam. Higher
strength concretes may be more susceptible to spalling in fires, and steel structures can suffer from loss of
strength and stiffness at elevated temperatures. A discussion is included in Section 4.1.11 of AGBT Part 2:
Materials for fire damages to bridges.

Figure 4.8: Pretensioned precast bridge beam after exposure to fire
4.4 Components
For many road agencies, bridge expansion joints can be the most common defect requiring repair and
maintenance. It is very uncommon for bridge expansion joints to fail because the joint design did not allow
for the actual movement, but it is quite common for expansion joints to fail because some part of the system
breaks.
As discussed in Section 15 of AGBT Part 3: Typical Superstructures, Substructures and Components, for
movement ranges up to 80 mm, the strip seal joint is the most common type of joint installed. This
comprises a rubber seal held in cast aluminium retainer plates that are bolted into the concrete. For larger
movement ranges up to about 300 mm, finger plate expansion joints are usually used. Again, the finger
plates are anchored in place by bolting into the concrete. In order to sustain the frequent load cycles as
wheels travel across the joint, the anchor bolts must be pretensioned, and this requires good anchorage into
well compacted concrete. Unfortunately, the plates and anchor bolts, with the associated reinforcing steel,
can make placing of concrete in this critical area quite difficult, and so it is important to take extra care when
placing and compacting concrete in this area.
If the concrete is not well compacted, the bolts will lose pretension, leading to loosening of the retainer plate.
Ultimately failure can occur by bolt fracture or by failure of the concrete under the plate.
Figure 4.9 and Figure 4.10 show examples of poorly compacted concrete around the expansion joint anchor
bolts. Retainer plates should always be lifted after the concrete has been cast to check on the quality of the
concrete.

Figure 4.9: Poorly compacted concrete at an expansion joint – example 1
Figure 4.10: Poorly compacted concrete at an expansion joint – example 2

Figure 4.11 shows a finger plate expansion joint that has failed as a result of disintegration of the concrete
under the finger plate. Reinforcement around the anchor bolts should be carefully detailed to distribute the
tension force from the anchor bolts (Figure 4.12).
Figure 4.11: Failure of a finger plate expansion joint due to disintegration of the concrete
Figure 4.12: Reinforcement detailing at expansion joint anchor bolts

Where large movements, say in excess of 300 mm, must be accommodated at the expansion joint, a
modular expansion joint is usually installed. Failures of these large joints have occurred in several Australian
states, and the available specification for modular expansion joints which, if followed, should result in more
robust joints in the future, such as Roads and Maritime Services (2005).
Bridge bearings are required to allow for the movement of the bridge as a result of thermal movements,
creep and shrinkage, and applied loads. Older bridges may have steel bearings, which often lose their ability
for free movement as a result of corrosion. Also, the steel components can fail from fatigue or overload.
Figure 4.13 shows a steel rocker bearing that has sheared due to lateral movement.
Figure 4.13: Steel rocker bearing
Elastomeric bearings are the most common bridge bearing for medium span applications, and these have
proven to be a reliable, low maintenance bearing. Figure 4.14 shows a laminated elastomeric bearing where
the outer rubber casing has torn. This can allow corrosion of the steel laminates to occur over time.
Elastomeric bearings can creep out of position over time if the vertical load generates insufficient friction, and
if they do not have retainer plates fitted.
For larger spans and heavier loads, pot bearings are used. Again, these have proven to be a reliable
bearing; however, care is required in handling and fitting the bearing to make sure that the upper and lower
parts of the bearing do not separate, and are installed parallel. It is important that pot bearings are
manufactured within the required tolerances to avoid problems with extrusion of the confined elastomer. For
this reason, pot bearings should be inspected and tested prior to installation.

Figure 4.14: Laminated elastomeric bearing
Refer to Section 14 and Section 15, respectively of the AGBT Part 3: Typical Bridge Superstructures,
Substructures and Components for the detailed information on bridge bearings and expansion joints. Refer
also to Section 5.7 and Section 5.8, respectively of AGBT Part 7: Maintenance and Management of Existing
Bridges for common defects on bridge bearings and deck joints.
Several fatigue failures of light poles and sign gantries have occurred in Australia in recent years. Where
these items of road furniture can collapse onto the road, their design should include a fatigue assessment.
Figure 4.15 shows remnant holding down bolts from a cantilever sign gantry that collapsed as a result of
fatigue of the anchor bolts. Figure 4.16 shows a photograph of a light pole where the mast collapsed as a
result of a fatigue crack that developed at the mast to base plate weld. In both cases the base plate was not
supported by grout. If base plates are designed to be grouted, then the grouting must be properly specified
and constructed. In general, dry pack grouting is not suitable for larger base plates, and high flow non-shrink
grout, properly installed, is the most reliable method (Figure 4.17).

Figure 4.15: Fatigue failure of sign gantry anchor bolts
Figure 4.16: Fatigue failure of a light pole mast

Figure 4.17: Grouting a sign gantry base plate
Further discussions on various bridge components can be found in AGBT Part 3: Typical Superstructures,
Substructures and Components.
4.5 Construction
Construction quality is obviously a key factor affecting bridge performance. In this section several examples
are given of construction quality issues.
The safety of a bridge during construction has been the responsibility of the construction contractor, but
increasingly it is being recognised that construction safety is affected by the designer, and they have a
responsibility in this regard. Figure 4.18 is a photograph of prestressed concrete I beams that collapsed due
to a lack of bracing during erection.

Figure 4.18: Collapse of beams during construction due to lack of temporary bracing
Figure 4.19 illustrates the problem that can occur when beams are cast with an extreme skew. The rotation
that occurs at transfer of prestress causes a local stress concentration at the acute end, and spalling of the
concrete frequently occurs.
Figure 4.19: Spalling of skew precast beams

Bored piles are difficult to inspect unless exposed due to, for example, top down construction. The difficulty
of fitting a rigid reinforcing cage into an irregular bored shaft can result in collapse of the spacers which are
used to maintain cover to the concrete (Figure 4.20). This can lead to loss of cover (Figure 4.21). The
specified reinforcing cage diameter plus cover should be less than the specified bored shaft diameter in
order to allow for the irregularity of the shaft walls. When placing the concrete in bored piles it is essential to
ensure that the sides of the shaft are stabilised and water is displaced, otherwise foreign material can
become included in the pile (Figure 4.22).
Figure 4.20: Collapse of reinforcing spacer in a bored pile

Figure 4.21: Exposed reinforcing in a bored pile
Figure 4.22: Inclusions in a bored pile

Good compaction of concrete is essential to the durability of concrete structures. This has been mentioned
above in connection with expansion joint anchors. Another area where inadequate compaction frequently
occurs is in the barrier stitch joint favoured by several road agencies. The interface between the precast
barrier and the top of the in situ stitch can allow water to come into contact with the reinforcing unless special
care is taken to compact the concrete at this position (Figure 4.23).
Figure 4.23: Inadequate concrete compaction at the top of the in situ concrete
Cracking of concrete must be addressed during both the design and construction stages. If good concreting
practices are not rigorously observed, excessive cracking can occur soon after concrete has been cast.
Figure 4.24 is an example of the crack repair that was undertaken on a bridge deck because the fresh
concrete was not adequately protected against hot and windy conditions. Figure 4.25 shows a photograph
of a core through the concrete deck showing the depth of the early age cracking (and also showing that the
crack injection penetrated the crack over its full depth).

Figure 4.24: Crack repair as a result of early age cracking
Figure 4.25: Deck slab core showing extent of crack and repair

The 500 grade reinforcing steels that are in common use in Australia need reasonable care to ensure that
the available ductility of the steel is not exhausted. Care must be taken to prevent the risk of cracking which
can occur as a result of repeated bending of grade 500 reinforcing steel which is more brittle than lower
strength reinforcement. Welding reinforcing steel, especially in areas that have been strain hardened by
bending (Figure 4.26) can lead to loss of both strength and ductility, and is not permitted.
Figure 4.26: Welding of reinforcing steel at bends can cause loss of strength and ductility
Bolts on structural steelwork connections are usually fully tensioned. If the contact surfaces are not properly
prepared, the bolt tension will not be developed, and the joint may not have the capacity anticipated by the
design. Figure 4.27 shows tension bolts on a surface with a three coat paint system. The paint surface will
creep under the applied load, and it is not capable of developing any significant friction between contact
surfaces.

Figure 4.27: Tensioning of bolts against a painted surface
Refer to AGBT Part 6: Bridge Construction for a discussion on various bridge components that may affect
the bridge performance.
4.6 Maintenance and Operation
Maintenance of bridges is essential to ensure that bridge performance is maintained. Some of the issues to
be addressed include tightening expansion joint anchor bolts, inspecting and maintaining bridge bearings,
and repairing and replacing protective coatings. Off structure maintenance affects bridge performance also –
the roughness of bridge approaches can affect the dynamic loads that are applied to a bridge. All road
agencies have maintenance manuals and maintenance procedures that direct how these activities will be
managed.
Overloading of bridge structures can lead to premature failure of bridge components, and in extreme cases
can lead to the collapse of a bridge. Enforcement measures to deter overloading are an important
contributor to the long-term performance of bridges. Where heavy loads are frequent, even when they are
within legal loading limits, the deterioration of a bridge can be accelerated. Fatigue failures of bridges in
Australia are not common, but are increasing. There is some evidence that frequent heavy loads on
composite bridges has contributed to premature failure of the bridge deck.
Bridges that are subject to scour may need to be maintained after heavy flows in the stream or river, as
scour can lead to partial loss of support (Figure 4.28) or on occasions scour can cause collapse of a bridge.

Figure 4.28: Scour of a bridge abutment
Source: VicRoads (n.d.).
Refer to AGBT Part 7: Maintenance and Management of Existing Bridges for detailed discussions on these
topics.

5. Quality Assurance in Bridge Projects
5.1 Introduction
Quality is defined by the American Society for Quality (2017) as ‘a subjective term for which each person or
sector has its own definition’. In technical usage, quality can have two meanings:
1. the characteristics of a product or service that bear on its ability to satisfy stated or implied needs
2. a product or service free of deficiencies.
AS/NZS ISO 9000 defines quality as the ‘degree to which a set of inherent characteristics of an object fulfils
requirements’. In many Australian road agencies’ context, the adopted definition of quality is both
conformance to requirements and fit-for-purpose.
The concept of quality control was developed in the 1920s (American Society for Quality 2017), following the
Industrial Revolution and the rise of mass production, when it became important to better define and control
the quality of products. Originally, the goal of quality was to ensure that engineering requirements were met
in final products. Later, as manufacturing processes became more complex, quality developed into a
discipline for controlling process variation as a means of producing quality products.
Quality assurance and auditing became in effect in the 1950s. The quality regime expanded to include the
quality assurance and quality audit functions. The drivers of independent verification of quality were primarily
industries in which public health and safety were vital.
Total quality management (TQM) was first introduced in the 1980s. Industry realised that quality was not just
the domain of products and manufacturing processes, and total quality management (TQM) principles were
developed to include all processes, including management functions and service provision.
In today’s practice, quality is managed through a quality management system (QMS), which includes all
activities of the overall management function that determine the quality policy, objectives, and responsibilities
and their implementation. A management system provides the means of establishing a policy and objectives
and the means to achieve those objectives.
A QMS can include the following (AS/NZS ISO 9000):

• quality planning: setting quality objectives and specifying necessary operational processes and related
resources to achieve the quality objectives
• quality assurance (QA): providing confidence that quality requirements will be fulfilled
• quality control: fulfilling quality requirements
• quality improvement: increasing the ability to fulfil quality requirements.
According to AS/NZS ISO 9000, QA comprises administrative activities and procedures implemented in a
QMS so that the requirements and goals for a product, service or activity can be fulfilled.
In the following sections, the background information on the QA in bridge projects is discussed, together with
various aspects of QA in the current practice.
5.2 Applicable Standards/Legislative Requirements
Generally, Australian and New Zealand road agencies cite the following standards for the QA practices:
• AS/NZS ISO 9000-2016, Quality Management Systems: Fundamentals and Vocabulary
• AS/NZS ISO 9001-2016, Quality Management Systems: Requirements.

In addition, most road agencies have their own QA specifications for infrastructure projects, for example:
• NZ Transport Agency Model Quality Management System for NZ Transport Agency-appointed Warrant of
Fitness and Certificate of Fitness Inspecting Organisations (NZ Transport Agency 2014)
• TMR MRTS50 Specific Quality System Requirements (TMR 2016)
• Roads and Maritime QA Specification Q6 Quality Management System (Type 6) (Roads and
Maritime 2013.
Refer to the relevant road agency’s specification for the details of the applicable QA requirements.
5.3 QMS Models
AS/NZS ISO 9000 and AS/NZS ISO 9001 cover the interactions between multiple parties in a quality model,
including interested parties (stakeholders), customer and providers. An example of the interactions in a
traditional construct-only model used in bridge construction with six or more levels of interaction between
many parties is shown in Figure 5.1. The use of QA in modern procurement models is discussed in
Section 5.4.3.
In most current situations, both customers and the providers of products and services have their own QMS
based on the principles and requirements set out by AS/NZS ISO 9001.
Figure 5.1: Quality interactions in a typical construction-only bridge contract
Source: Dr J Fenwick (n.d.).

5.3.1 Quality Management (QM) Principles
AS/NZS ISO 9001 is based on the following QM principles:

• customer focus: the primary focus of QM is to meet customer requirements and to strive to exceed
customer expectations
• leadership: leaders at all levels establish unity of purpose and direction and create conditions in which
people are engaged in achieving the organisation’s quality objectives
• engagement of people: competent, empowered and engaged people at all levels throughout the
organisation are essential to enhance the organization’s capability to create and deliver value
• process approach: consistent and predictable results are achieved more effectively and efficiently when
activities are understood and managed as interrelated processes that function as a coherent system
• improvement: successful organizations have an ongoing focus on improvement
• evidence-based decision making: decisions based on the analysis and evaluation of data and information
are more likely to produce desired results
• relationship management: for sustained success, organisations manage their relationships with relevant
interested parties, such as providers.
The QMS manages the interacting processes and resources required to provide value and realise results for
relevant interested parties. The Plan-Do-Check-Act cycle (PDCA) (Figure 5.2) can be applied to all
processes and the QMS as a whole:
• Plan: establish the objectives of the system and its processes, and the resources needed to deliver
results in accordance with customers’ requirements and the organization’s policies, and identify and
address risks and opportunities.
• Do: implement what was planned.
• Check: monitor and (where applicable) measure processes and the resulting products and services
against policies, objectives, requirements and planned activities, and report the results.
• Act: take actions to improve performance, as necessary.

Figure 5.2: PDCA cycle
Note: Number in brackets refer to the clauses in AS/NZS 9001.
Source: AS/NZS 9001.
While AS/NZS ISO 9001 quality model is designed to cover any situation, it does not clearly describe the
economics of risk, testing, inspection and prevention, specific to any one industry.
5.3.2 Requirements for Agencies
The NSW Department of Finance, Services and Innovation (2013) provides a guideline for setting the
requirements that agencies must meet in implementing their QMS, aligning with the provisions specified by
AS/NZS ISO 9001. These requirements include both organisational activities and project and contract
activities, as follows.
Organisational activities
The agency shall select and specify appropriate QM requirements in the request for tender documents and
contract documents. QM activities including monitoring the conformity of service providers with quality
requirements must be implemented.
For each procurement activity, sufficient resources shall be allocated to manage quality, including personnel
with the appropriate knowledge, skills and experience, to cover the defined practices, processes and
procedures required for tender/contract documentation, management and activities generally.

Appropriate training shall be provided to personnel, including QM requirements, QMS, assessment, review
and monitoring the implementation of a service provider’s QMS.
The agency shall develop procedures and implementation plans for the QMS, QM plans (QMPs), and
inspection and testing plans (ITPs).
Records will be maintained of the assessment and review of the QMS, QMPs and ITPs, as well as the
implementation of these plans.
Project and contract activities
The level of risk must be determined for each contract, including the probability or likelihood and
consequences or impact of nonconformity with specified requirements (including quality, technical, work
health and safety, environmental, financial and operational).
Quality requirements for a QMS, QMPs and ITPs shall be specified in the request for tender and contract
documents.
The need for, and scope of, monitoring activities for a contract are assessed and contract conditions allowing
for such activities included in the contract documents. These may include audits/reviews arranged and
resourced by both the service provider (1st party) and the agency or other customer (2nd party). Customers
may use the results of service provider audits/reviews.
Potential service providers’ QM abilities are assessed in a tender evaluation process, using the identified
evaluation criteria. Possible evaluation criteria include: the status of their QMS; and/or the nature of the QM
implemented on current and/or recent comparable contracts. This may include assessment of a potential
service provider’s past QMPs, and/or past ITPs.
The service provider’s QMP and/or ITPs should be reviewed for conformity with the requirements at the
commencement of the contract.
The performance of the service provider in meeting quality requirements should be evaluated and included in
regular performance reports prepared for and addressed under the contract.
5.3.3 Requirements for Service Providers
Similarly, the service provider must meet the quality requirements for both organisational and project and
contract activities, as follows.
Organisational activities
The service provider develops a QMS, which depends on the products and services to be delivered and the
particular customer requirements.
Resources with sufficient knowledge, skills and experience in QM are allocated. The provider has corporate
procedures for developing, implementing and maintaining their QMS, QMPs, and ITPs, as applicable, and to
monitor their effective implementation with contracts.
Service providers that purchase or subcontract products and/or services would ensure each customer’s
quality requirements are reflected in the applicable purchase or subcontract documents.
The provider addresses the applicable agency QMS requirements and other conditions of tendering for the
type and value of products and services involved.

Project and contract activities
The requirements for a service provider's QMS, QMPs and ITPs are specified in the request for tender
documents and contract documents. As a minimum, the following contract conditions would include:
• preparation of a QMP and/or ITPs for the work covering the service provider and its service providers, or
allowing for each to provide a QMP and ITPs, and the submission of these or certification of their
conformity to the contract Principal before applicable work commences
• reviewing and updating the QMP and/or ITPs
• planning and conducting its reviews, audits, inspections, witnessing and surveillance of the
implementation of the QMS (where applicable), QMP and/or ITP
• controlling nonconforming services/products and undertaking appropriate corrective and preventive
actions
• payment made only for work that conforms with specified requirements
• establishing, and maintaining records of the above actions
• providing access to the work sites, information, documentation, records, explanations, personnel and
accommodation necessary for any 2nd party audits/reviews.
When a potential service provider is not required to have a QMS certified by the agency, its ability to
undertake QM for a contract would normally be assessed by the agency. The compliance of the service
provider’s QMS with the agency’s requirements and criteria would be assessed based on documented
procedures for the development of the QMS, past QMPs, and ITPs used on recent comparable contracts.
Refer to the Austroads Guide to Project Delivery: Part 3: Contract Management (Austroads 2014b) for further
reading on the requirements of a QMS in road construction context.
5.4 QA Issues in Bridge Projects
To successfully implement a QMS in a bridge project, considerations should be given to the following specific
areas.
5.4.1 QA Interactions in a Bridge Contract
The following are suggested for inclusion in a bridge contract:

• The ‘customer’ is the road agency. There are more customers in the supply chain (motorists, freight
industry, maintenance contractors etc.). However, for the purpose of this Part, the road agency acts as
agent to ensure the product delivered (a road link, bridge, etc.) is fit-for-purpose for subsequent
customers.
• The road agency normally appoints an administrator (or the superintendent or the Principal) to administer
the construction contract. This person can be an employee of the agency, a consultant or some other
party. It is assumed the administrator has the knowledge, skill and experience to accurately interpret and
clarify all the plans and specifications and ensure the contractor understands what is required and
delivers it.
• The main contractor is responsible in a legal and technical sense to deliver the works as specified for the
agreed payment and under its QMS.
• The contractor also appoints a QM representative under the contract to manage and administer it’s QMS
in accordance with the contract specifications.
• The contractor will engage one or more subcontractors in a chain that may have several levels. A
precast-concrete manufacturer may supply concrete bridge components or culverts, and in turn has
subcontractors who supply formwork and premixed concrete (both critical to the final quality). The
subcontractors may be prequalified by the road agency.

• At the start of the supply chain are the material suppliers who may supply a subcontractor, the main
contractor, or directly to the construction agency depending on circumstances. These suppliers (cement,
aggregate, steel, prestressing strand, etc.) may be manufacturers or importers from overseas suppliers.
The quality of these materials is fundamental to the quality of the finished product. Some road agencies
require that the material suppliers be registered in a prequalified scheme such as a Quarry Registration
System (TMR 2016).
All these parties to a typical bridge construction contract need to interact in a fairly complex way as illustrated
in Figure 5.1.
There will usually be many other stakeholders involved in a bridge project, including:
• services authorities (water, telecom, etc.)
• adjacent landholders
• environmental consultants, authorities, etc.
• local government agencies.
Although these add to the complexities of managing the construction processes, and may change the scope
of a project or cause significant restraints, they normally do not affect the quality of construction, and will not
be considered further in this part.
5.4.2 Timescale and Durability
Many of the concepts of product quality come from the consumer durables used in everyday life. Most of
these have relatively short lives:
• computers – 3–5 years, rapid obsolescence in technology
• cars – 5–15 years, with manufacturers’ warranties for 1–3 years (some 5 years). Obsolescence due to
style change, wear and tear, safety changes, fuel economy
• refrigerators – 10–20 years, obsolescence due to rust, loss of seal and mechanical failure.
The failure rates for these products have the shape shown in Figure 5.3.
Figure 5.3: Failure rates versus service life of a product
Source: Dr J Fenwick (n.d.).

In this Figure:
• The early failures (A) are caused by manufacturing faults and usually appear early in the product life. The
customer is protected by the 12 months warranty, or some longer warranty period.
• Period (B) is the useful operating life of the product where ‘failure’ (and subsequent maintenance costs) is
quite low.
• Period (C) is the period of steeply rising ‘failure’ and maintenance costs, finishing when the product is
‘dumped’ and a replacement purchased.
Modern bridges have a similar failure pattern, with important differences:

• Early failure (A) is usually during construction due to some error in the construction procedures (usually
due to failure under gravity forces).
• Period (B) is normally specified as the ‘100 year service life’, when failure rates and maintenance costs
are very low. However, if construction has been very poorly specified and controlled, period (B) can be
as short as 10 years (e.g. poor quality concrete and low cover in a marine environment).
• Period (C) is the loss of capacity due to corrosion and other environmental effects, culminating in a
decision to replace to cut maintenance costs.
The long life expectancy for bridges means that normal ‘manufacturers’ warranties’ only apply during period
(A) – construction, where the contractor has always borne the risk.
Maintenance periods specified in contracts are generally limited to 30 years which does not protect the asset
owner against poor construction practice leading to the development of serious defects during period (B).
5.4.3 QA in Different Procurement Models
In traditional contracts the designer acts on the asset owner’s behalf to ensure that the project is fit for the
owner's purpose. The asset owner (who is interested in obtaining adequate quality) will carefully check that
the design meets its requirements before going to tender.
In the current project delivery models, delivery of quality in construction depends on the selected model
which can be one of the following (see Section 2 of AGBT Part 4: Design Procurement and Concept Design
for details):
• construct only
• design and construct (D&C)
• design, build and own (DBO)
• build, own, operate and transfer (BOOT)
• early contractor involvement (ECI)
• public private partnership (PPP)
• alliance.
However, quality will be independent of the procurement model provided that the QM requirements
described in Section 5.3.2 are adopted. In these models, the contract work administration and design and
construction quality risks are typically allocated to different party as follows (Austroads 2014a):
Construct only
• Construction works commonly are overseen by a superintendent, principal’s representative (PR) or
principal’s authorised person (PAP).
• Resource commitment for project owners may be high depending on the degree of testing, auditing and
general surveillance required.

• The risk of any design-related matters rests with the project owner, which must seek recourse from
external design consultants re: design-related errors or omissions.
• The contractor must construct the works in accordance with the design and specifications.
D&C and variants

• Construction works are commonly overseen by a superintendent, PR or PAP.
• Independent verifiers may be required for particular aspects of the design or construction.
• Resource commitment for project owners may be high depending on the degree of testing, auditing and
general surveillance required.
• The contractor bears the risk of design, including warranting the design’s fitness for purpose.
• The contractor must construct the works in accordance with the approved design and the specifications.
ECI
• Stage 1 (preliminary planning and design) is governed by the ECI agreement and Stage 2 (detailed
planning & design and construction) is governed by a D&C agreement.
• In the civil (road and bridge) sector, the following are typically included as part of the administration
arrangements
– a leadership team, whose role is to monitor performance, help resolve disputes and provide general
direction and leadership
– a management team, which includes the PR/PAP and contractor’s project manager, manage
day-to-day project activities.
• In some circumstances, independent verifiers may be engaged for particular aspects of the design or
construction.
• A facilitator may be required to help build relationships across the team(s).
• The level of resourcing is significant for all parties during Stage 1 due to the integrated nature of the
project team and time commitments required to be made by senior personnel.
• Design risks are negotiated and allocated to the party best placed to control each aspect of the risk –
generally the contractor.
• The contractor must construct the works in accordance with the agreed design and specifications.
PPP
• Typically, the arrangement includes the project owner, project sponsor which may be a syndicate of
banks and/or other financiers, construction contractor and/or asset operator.
• Project owner’s resources required at the front end of the project are very high, but the degree of
resourcing required to oversee the contractual arrangements is not generally significant once the project
works are complete.
• The private sector partner(s) generally assumes the financing and cost risks of the design, and is required
to warrant the design’s fitness for-purpose.
• The private sector partner(s) must construct the works in accordance with the agreed design and
specifications.
Alliance
• The alliance arrangement is governed by an alliance leadership team (ALT) and alliance management
team (AMT). These teams (ALT and AMT) perform a similar role to the ECI’s.

• Independent verifiers may be engaged for particular aspects of the design or construction.
• Facilitators are commonly engaged to build relationships within and across the ALT and AMT for the life
of the project.
• A dispute resolution board may also be established to help resolve any disputes that cannot be managed
at AMT or ALT level.
• The time commitment required to effectively resource an alliance, including the level of commitment from
senior executives, is significant.
• Design risk is shared, but the non-owner participants (NOPs)’ exposure may be capped as part of the
‘pain share, gain share’ arrangement.
• Construction must meet the quality standards outlined in any agreed key result areas. The quality risk is
shared between the alliance participants.
5.4.4 Pre-qualification and Pre-registration
Australian and New Zealand road agencies use pre-qualification and associated systems to ensure
contractors have the financial, technical and quality-related capability to deliver contracted works and
services. The purpose of pre-qualification is also to minimise risk, reduce tendering costs to both tenderers
and tendering agencies.
These systems provide a listing of contractors with technical and operational capacity, financial resources,
QMS, work health and safety management systems, environmental management systems and performance
records which have been assessed by the agency and accepted as being suitable for the execution of work
up to a nominated value within a particular technical category.
Pre-qualification was introduced in the 1980s in response to legislation that required road agencies to do
everything ‘reasonably practical’ with respect to meeting environmental and safety obligations. The concept
of pre-qualification was re-visited in 1997 when a National Code of Practice for the Construction Industry was
adopted. Pre-qualification was one strategy to drive the development of an industry committed to best
practice, international competitiveness and ethical behaviour. Each road agency had its own individual
pre-qualification requirements and processes. This represented a duplication of effort and increased the
administrative burden across Australia by road agencies and contractors alike.
Recently, Austroads has developed the National Pre-Qualification System (NPS) to create a harmonised
framework for roadworks and bridgeworks construction contracts (Austroads 2010). It requires that
companies wishing to submit tenders to Australian road agencies be prequalified under the NPS.
The key features of the NPS include:

• consistent eligibility requirements and pre-qualification categories across participating agencies
• a company that is prequalified in one jurisdiction may have that pre-qualification recognised by other
participating agencies
• minimisation of unique localised systems and requirements
• consistent contractor performance reporting and sharing of this information across road authorities
• the promotion of best practice in the road and bridge construction industry.
Pre-qualification consists of a continuous process of:

• an initial assessment of a contractor’s capabilities at the time of lodgement of an application (including its
operational management systems)
• further financial and/or technical checks during the tender assessment process, before a contract is
awarded

• assessment of a contractor’s performance in a contract, during and at the completion of contracts, and at
other times when a review may be warranted
• annual review of financial accounts as appropriate
• review of the technical capabilities after any significant changes within the company
• renewal via the submission of a new application.
Guidelines and templates for the pre-qualification process can be found in Austroads (2016).
In cases where the type of work in the request for tender (RFT) is not adequately catered for by the national
or jurisdictional prequalification systems, or is unusually large and/or technically complex, then
pre-registration of tenderers could be undertaken (Austroads 2014b). Pre-registration, which is essentially a
type of project-specific pre-qualification, ensures that only contractors of proven capability and experience in
the particular type of work detailed in the RFT documents will be invited to submit tenders. The RFT would
then be supplied to only those tenderers who were pre-registered by the agency.
5.4.5 Control of Nonconforming Products
AS/NZS ISO 9001 requires that products that do not conform to the specified requirements are identified and
controlled to prevent their unintended use or delivery. Appropriate action shall be taken based on the nature
of the nonconformity and its effect on the conformity of products and services. This shall also apply to
nonconforming products and services detected after delivery of products, during or after the provision of
services.
It is important to prevent the production of nonconforming product as early as practical, that is, the first
product produced. If it has significant defects, it must be rejected, so the producer fixes the production
process to achieve conformance of later production.
Failure to reject an early non-conformance can be interpreted as acceptance, even though the contract
documents specifically state otherwise. Contractors may continue to produce a large number of
nonconforming products, and it will be increasingly difficult to resolve the problem if action is delayed.
Early or immediate rejection of nonconforming product will assist the contractor to successfully deliver a
project.
One or more of the following actions can be taken to deal with nonconforming outputs:
• correction
• segregation, containment, return or suspension of provision of products and services
• informing the customer
• obtaining authorization for acceptance under concession.
In addition, documented records of the non-conformance must be retained with detailed descriptions of the
nonconformity, the actions taken, any controlled departure from standards and the authority deciding the
action in respect of the non-conformity.
In practice, many quality defects may be hidden, and cannot be economically detected at the end of the
process. This can lead to premature failure and rapidly rising maintenance costs. If the time lapse is several
years, the owner has little chance of recovering the cost of repair or replacement from the contractor. In
order to reduce the risks of hidden defects, AS/NZS ISO 9001 specifies a number of requirements for the
customer to monitor, inspect and control product quality and acceptance (Appendix A).
Refer to Andrews-Phaedonos (2017) for some examples of nonconforming work where less than
100% compliance was unacceptable.

5.4.6 Hold Points and Witness Points
Construction specifications can include hold points and witness points. A hold point means an identified
point in a process beyond which the contractor must not proceed without written authorisation from the
administrator. Hold points apply in the following circumstances:
• as specified in the contract or as otherwise nominated by the administrator
• on issue of a non-conformance report
• on issue of a corrective action request by the administrator.
To release the hold point, the administrator or independent verifier conducts checks to ensure the process is
conforming.
A typical example can occur prior to placement of concrete. The right size and number of reinforcement bars
should be checked, together with cover and cleanliness of the form (all tie wire removed by air jet and
magnets for example) and the form is watertight.
A witness point requires the contractor to inform the superintendent/verifier that an operation will occur, and
the superintendent/verifier attends if they consider it necessary. Attendance is based on risk assessment.
While it is prudent to attend the first few cycles of each new construction process, long periods of conforming
construction can give the superintendent/verifier sufficient confidence to reduce the frequency of inspection.
5.4.7 Inspection and Testing
Compliance inspections and testing to ensure compliance with the contract requirements are generally
conducted by the contractor.
Compliance sampling and testing must be carried out by the National Association of Testing Authorities,
Australia (NATA)-accredited laboratories certified for the relevant tests.
Results from compliance tests are to be provided to the contractor and the administrator at the same time. If
the results indicate non-conformance, no further testing shall be permitted until a non-conformance report
has been submitted and corrective action has been approved by the administrator.
Major manufactured materials in road and bridge construction (bitumen, cement, steel, etc.) can be quality
assured in two ways:
• testing at source, with identification and traceability down to the individual batches, products and
components used in construction
• testing on site, with site traceability into products and components.
In general, it is much more economical to test at source and have adequate traceability. The cost of
adequate quality control by sampling and testing on site is so high that it is rarely done, except for concrete.
Most large manufacturers have a critical interest in their reputation and the quality of their products and
documentation, but some international suppliers might not supply reliable certification.
Where possible, industry-specific product certification schemes can be used to provide independent testing
and quality control. As an example, in Australia, a non-profit organisation Australian Certification Authority
for Reinforcing Steels Ltd (ACRS) has been set up to administer a third party product certification scheme for
steel reinforcement and prestressing strand. The organisation is supported by key construction industry
bodies, including Austroads. The reinforcing standards AS/NZS 4671 and the prestressing standard
AS/NZS 4672 allow for voluntary third party product certification as one of the methods to prove compliance.
Refer to the ACRS website (ACRS 2015).

References
ACRS 2015, Welcome to steelcertification.com, webpage, Australian Certification Authority for Reinforcing
Steels, Sydney, NSW, viewed 19 July 2017, <www.acrs.net.au>.
American Association of State Highway Officials (AASHO) 1953, Bridge design specification, AASHO:
Washington.
American Society for Quality 2017, Quality glossary - Q, webpage, ASQ, viewed 19 July 2017,
<https://asq.org/quality-resources/quality-glossary/q>.
Altmann, K, Butcher, M, Rodda, L, Stacey, B, Stewien, R & Venus, R 1999, Ponds, ponts & pop-eye: notes
for an afternoon afloat on Adelaide's River Torrens, Institution of Engineers Australia, South Australian
Division, Adelaide, SA.
Anderson, JA 1899, ‘Notes on the adulteration of Portland cement (paper & discussion)’, Proceedings of the
Victorian Institute of Engineers 1892-1899, vol. II, pp. 1-14.
Andrews-Phaedonos, F 2017, ‘Ensuring quality and durability in concrete construction for major
infrastructure’, Austroads bridge conference, 10th, 2017, Melbourne, Victoria, Australia, ARRB Group,
Vermont South, Vic, 13 pp.
Australian Transport Council 2011, National road safety strategy 2011-2020, ATC, Canberra, ACT.
Austroads 2010, National pre-qualification system for civil (road and bridge) construction contracts,
AP-R371-10, Austroads, Sydney, NSW.
Austroads 2014a, Building and construction procurement guide: principles and options, AP-G92-14,
Austroads, Sydney, NSW.
Austroads 2014b, Guide to project delivery: part 3: contract management, 2nd edn, AGPD03-14, Austroads,
Sydney, NSW.
Austroads 2016, Guidelines: national pre-qualification system for civil (road and bridge) construction
contracts, AP-C96-16, Austroads, Sydney, NSW.
Concrete Society 2002, Durable post-tensioned concrete bridges, 2nd edn, technical report no. 47, Concrete
Society, Berkshire, UK.
Department of Finance, Services and Innovation 2013, Quality management systems guidelines for
construction, ProcurePoint, Sydney, NSW.
Department of the Environment 1973, Inquiry into the basis of design and method of erection of steel box
girder bridges, part II: design rules, Department of the Environment, HMSO, London, UK.
Fraser, DJ 1985, ‘Early reinforced concrete in New South Wales (1895-1915)’, Multi-Disciplinary Engineering
Transactions, vol. GE9, no. 2, pp. 82-91.
Holgate, A n.d., John Monash: engineering enterprise prior to WW1, webpage, viewed 19 July 2017,
<http://www.aholgate.com/jm_intro.html>.
NZ Transport Agency 2014, Model quality management system for NZ Transport Agency-appointed warrant
of fitness and certificate of fitness inspecting organisations, NZTA, Wellington, NZ.
NZ Transport Agency 2016a, Bridge manual, 3rd edn, SP/M/022, NZTA, Wellington, NZ.
NZ Transport Agency 2016b, Highway structures design guide, NZTA, Wellington, NZ.
O’Connor, C 1985, Spanning two centuries: historic bridges of Australia, University of Queensland Press, St.
Lucia, Qld.
Office of Environment and Heritage 2017, Peats Ferry road bridge over Hawkesbury river, Office of
Environment and Heritage, Sydney, NSW, viewed 16 May 2017,
<http://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?ID=4309666>.
Pearson, BJ, Best, RE & Fraser, DJ 1987, ‘Engineering heritage and the bridges of New South Wales’, Multi-
Disciplinary Engineering Transactions, vol. GE11, no. 2, pp. 92-100.

Queensland Department of Transport and Main Roads 2016, Specific quality system requirements, technical
specification MRTS50, TMR, Brisbane, Qld.
Roads and Traffic Authority 2000, Timber beam bridges: study of relative heritage significance of RTA
controlled timber beam road bridges in NSW, Roads and Maritime Services, Sydney, NSW.
Roads and Maritime Services 2005, Modular bridge expansion joints, QA specification B316, edn. 2, rev. 1,
RMS, Sydney, NSW.
Roads and Maritime Services 2012, Bridge aesthetics: design guidelines to improve the appearance of
bridges in NSW, RMS, Sydney, NSW.
Roads and Maritime Services 2013, QA Specification Q6 Quality Management System (Type 6), IC-QA-Q6,
Edn 1, Rev 10, RMS, Sydney, NSW.
Woodward, CM 1881, A history of the St. Louis Bridge, GI Jones and Company, St Louis, MO, USA.
Australian/New Zealand Standards

AS(AS/NZS) 5100-2017 (set), Bridge design.
AS 5100.1-2017, Bridge design: scope and general principles.
AS/NZS ISO 9000-2016, Quality management systems: fundamentals and vocabulary.
AS/NZS ISO 9001-2016, Quality management systems: requirements.
AS/NZS 4671-2001, Steel reinforcing materials.
AS/NZS 4672-2007, Steel prestressing materials.

AS/NZS ISO 9001 Clauses for Consideration
There are a number of clauses in AS/NZS ISO 9001-2016 which indicate a customer should monitor
supplier's processes. These are the responsibilities of a road agency in its role as customer.
Table A 1: Relevant AS/NZS ISO 9001 clauses worthy of customer monitoring
Clause
Introduction general Adoption of a QM system should be a strategic decision of an
organisation that can help to improve its overall performance and provide
a sound basis for sustainable development initiatives. The process
approach employed in this International Standard incorporates the Plan-
Do-Check-Act cycle and risk-based thinking.
4.4 Quality management system and its The organisation shall establish, implement, maintain and continually
processes improve a QMS, including the processes needed and their interactions.
5.1.2 Customer focus Top management shall demonstrate leadership and commitment with
respect to customer focus.
7.1 Provision of resources The organisation shall determine and provide the resources needed for
the establishment, implementation, maintenance and continual
improvement of the QMS.
8.1 Operational planning and control The organization shall plan, implement and control the processes needed
to meet the requirements for the provision of products and services.
8.2 Requirements for products and The organization shall ensure:
services customer communication
determining the requirements for products and services
review of the requirements for products and services.
8.4 Control of externally provided The organisation shall ensure that externally provided processes,
processes, products and services products and services conform to requirements.
8.7 Control of nonconforming outputs The organisation shall ensure that outputs that do not conform to their
requirements are identified and controlled to prevent their unintended use
or delivery.

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Guide to Bridge Technology Part 1:

Introduction and Bridge Performance

2. Relationship to Bridge Design Standards ........................................................................................... 3

3. Influences on the Evolution of Australian and New Zealand Bridges .............................................. 5

4. Factors Affecting Bridge Performance .............................................................................................. 21

5. Quality Assurance in Bridge Projects ................................................................................................ 43

Austroads 2018 | page i

Austroads 2018 | page ii

1.2 Guide Structure

Table 1.1: Parts of the Guide to Bridge Technology

Part Title Content

Austroads 2018 | page 1

Part Title Content

Austroads 2018 | page 2

2. Relationship to Bridge Design Standards

2.1 Scope of AS 5100

Austroads 2018 | page 3

2.2 Scope of NZ Transport Agency Bridge Manual

2.3 Confirmation of Design Parameters by the Road Agency

Austroads 2018 | page 4

3. Influences on the Evolution of Australian and New

3.1 Timber Bridges in Australia

Austroads 2018 | page 5

3.2 The Age of Iron and Steel

Figure 3.1: Iron Bridge, Coalbrookdale

Austroads 2018 | page 6

Austroads 2018 | page 7

Figure 3.2: St Louis Bridge under construction

Austroads 2018 | page 8

3.3 Steel Truss and Truss-arch Bridges

Austroads 2018 | page 9

3.4 Steel Girder Bridges

Austroads 2018 | page 10

Source: Courtesy of University of Adelaide Archives.

3.5 Suspension Bridges

Austroads 2018 | page 11

3.6 Cable Stay Bridges

Source: RTA NSW (n.d.).

Austroads 2018 | page 12

3.7 The Rise of Concrete Bridges

Austroads 2018 | page 13

Source: Holgate (n.d.).

Austroads 2018 | page 14

Austroads 2018 | page 15

3.8 Bridge Aesthetics and Urban Design

3.9 Other Singular Events of Influence

3.10 The Development of the Bridge Design Standard

3.10.1 NAASRA Bridge Design Code

3.10.2 1992 Austroads Bridge Design Code

Austroads 2018 | page 16

• Section 4: bearings and deck joints

3.10.3 HB 77-1996 Australian Bridge Design Code

3.10.4 Standards Australia AS 5100 Bridge Design

3.11 The Development of Bridge Design Loading

3.11.1 A History of Bridge Design Loads

Austroads 2018 | page 17

Table 3.1: Design eras in Australia

Design era Design load Represents

Table 3.2: Design eras in New Zealand