Bridge Aesthetics

Bridge Aesthetics
Design guidelines to improve the appearance of bridges in NSW

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Contents
Foreword
2
01
Introduction
3
02
Design approach
9
03
The whole
15
04
The parts
25
05
The details
41
06
Particular conditions
49
Bibliography
56
Acknowledgments
Prepared by a collaboration of:
The Government Architects Office | RTA Operations Directorate, Bridge Section | RTA Road Network Infrastructure Directorate, Urban Design Section
Project team:
Wije Ariyaratne | Mark Bennett | Joe Canceri | Raeburn Chapman | Gareth Collins | Ian Hobson | Col Jones | Peter Mould | Ray Wedgwood
The information in this document is current as at July 2003.

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The whole
Foreword
It is nearly four years since the RTA published Beyond the
Bridges have been part of human settlement for thousands
Pavement: RTA Urban and Regional Practice Notes. In that time
of years. Historic bridges stand as evidence of the power and
the RTA has significantly changed the way it deals with the
influence of past societies. They vary greatly in style and
design of its roads and transitways.
reflect the culture and engineering innovation of their society.
In keeping with the Beyond the Pavement philosophy, this
They show the daring, engineering skill and craftsmanship of
document addresses the design and appearance of our
their builders and even in the simplest bridges we can find
bridges in a systematic and practical manner. It draws from
inventiveness and subtlety in working with the local context.
the wealth of design excellence in our bridge inventory as
Great bridges are audacious or beautiful enough to evoke
well as from past design problems.
wonder. Their primary function of linkage soon adopts a
It stresses that good bridge aesthetics need not be
symbolic function.
costly nor a maintenance burden, but are integral to good
A bridge in the landscape helps us interpret that landscape
engineering design.
by providing a scale and a reference to human intervention.
I commend these guidelines to the RTA and everyone
This was well defined by the famous Swiss architect Mario
involved in road and bridge design and look forward to
Botta when he said, “the bridge defines the valley”.
the outcomes.
Modern bridges exploit the latest technologies and
construction techniques. They allow us to challenge the
landscape in new ways and so impose our hand on the
landscape. It is important to do so well. Our impact on the
environment should be minimised, our understanding of the
Paul Forward
context should guide our solutions and our concern for
design should consider the look as well as the span. In short,
Chief Executive, RTA
our bridges should be beautiful.
November 2003
Major infrastructure will serve the community for many
decades. It should not just last, but also provide a lasting
legacy of excellence for future generations. Minor bridges at
the least should have good manners, a low maintenance
objective and a degree of finesse.This guide is intended to be
a small step towards that goal.
Chris Johnson
Government Architect
November 2003
[2]
Bridge Aesthetics
Foreword

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Introduction
1.1
Purpose of the guidelines
4
1.2
Aesthetics
5
1.3
The designers
5
1.4
Perception of bridges
6
1.5
Terminology
7

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Introduction
1.1 Purpose of the guidelines
‘Bridges are among the most ancient and honourable
members of society with a background rich in tradition
and culture. For countless generations they have borne the
burdens of the world and many of them have been great
works of art. As in most large families there are numerous
poor relatives. The modern bridge too often appears as a
workman performing its task for a minimum wage,
mechanically efficient but uneducated and ignorant of its
own ancestry. A worthy subject for serious consideration.’
Charles S Whitney 1929
The purpose of these guidelines is to help design teams
produce bridges of aesthetic value.
In addition, these guidelines will also help the RTA and
its advisors set down unequivocal aesthetic outcomes so
that consultants and contractors are made aware of
RTA requirements and can focus on innovation in achieving
those requirements.
The document is not intended for special iconic landmark
bridges such as the Anzac Bridge which have their own
design champions, but rather the more common road
bridges which are an abundant and highly visible element of
NSW highways.
A number of photographs of NSW bridges have
been included. It is not the intention to critically evaluate
these bridges but to use the images as lessons for future
bridge design.
There are always exceptions to design rules and it is not the
intention to provide a formula for good design.
‘A formula is a good servant but a bad master at any time.’
Charles Holden
Rather it is the intention to set down considerations and
principles, which will help, eliminate the worst aspects of
bridge design and encourage the best.
[4]
Bridge Aesthetics
Introduction | 01

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Introduction
1.2 Aesthetics
‘Beauty has been thought of as extraneous to
considerations of function, practicality, economy and
advancing technology. To many the word ‘aesthetics’ has
meant superfluous or artificial, like cosmetics.’
Paul Harbeson, Bridge Aesthetics
It is the intention of this work to encourage aesthetics to be
considered as an integral part of the design process. Every
The twin bridges over Mooney Mooney Creek demonstrate how good
part of the bridge has a role to play both structurally and
engineering design and good aesthetics are synonymous.
aesthetically in the whole.
As such the document is based around the premise that
there are a myriad ways to design and express structural
form and additional or ‘add on’ treatments are generally
unnecessary. Good bridge engineering and good aesthetics
are synonymous and only limited by the imagination and skills
of the bridge designer.
Finally it should be said that whilst personal tastes differ,
beauty is not simply a matter of taste alone. When qualities
such as proportion, order and symmetry are applied well,
people often agree that the object has aesthetic value
(whether they like it or not is another matter).When applied
badly there is often public outcry.
1.3 The designers
The designers are responsible for the look of bridges, they
must consider appearance as a major design imperative
along with strength, safety and cost.
For aesthetics to be successful, it must first be considered.
It should be an integral part of design and must be
considered both in the general form and all the details that
support it. The parts must be considered as to how they
contribute to the whole.
Standard details when used need to be reviewed for
their appropriateness to each project. They should be
regularly updated.
The designers of bridges are faced with many choices.
These guidelines aim to inform those choices and act as a
memory jog during the design process. Aesthetic ability is a
skill that can be developed, however, it must be seen as an
essential requirement for that development to occur.
01 | Introduction
Bridge Aesthetics
[5]

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Introduction
1.4 Perception of bridges
Bridges are seen from many angles and the viewers see them
from a variety of conditions. Bridges may be isolated objects
in the landscape, part of a suite of engineered infrastructure
or on a city street.They are seen from close up, faraway, from
rivers and other roads. Viewers can be standing still or
moving to or across a bridge at varying speeds and in a
variety of vehicles.
These guidelines assume viewing from all angles. The first
step of the design process is to establish the critical views
for the bridge. Further, there is the issue of illusion
The structure of the bridge over the Brunswick River at Brunswick Heads is
whereby the assembly of the parts can use visual devices to
not visible from the Pacific Highway, yet it forms a small but significant part
enhance the bridge by emphasising its apparent slenderness
of the landscape when seen from a local scenic viewpoint.
or visual continuity.
Generally bridges seem aesthetically more pleasing if they
are simple in form, the deck is thinner (as a proportion of
its span), the lines of the structure are continuous and
the shapes of the structural members reflect the forces
acting on them.
[6]
Bridge Aesthetics
Introduction | 01

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Introduction
1.5 Terminology
A problem that can hamper meaningful debate between designers is consistency of terminology. The following annotated
photographs set down the terminology used throughout these guidelines and should be understood by all involved in the bridge
design process. (Definitions sourced from RTA Structural Drafting Manual and the RTA Road Design Guide).
Superstructure – that part of the structure which
Transition pier – pier separating
Soffit – undersurface of the
supports traffic and includes deck, slab and girders.
different superstructure types.
bridge superstructure.
Substructure – that part of the structure, ie piers and
Pile cap – A reinforced concrete mass cast around
abutments, which supports the superstructure and
the head of a group of piles to ensure they act
which transfers the structural load to the foundations.
together and distribute the load among them.
Pile – a slender member driven into or formed in
the ground to resist loads.
Pier – a part of the substructure which
supports the superstructure at the end of
Safety / throw screen – protective fence
the span and which transfers loads on the
to deter the launching of objects from
Deck – bridge floor directly
superstructure to the foundations.
the bridge onto the highway below.
carrying traffic loads.
Span – the distance between points
Abutment – the part of the structure which
Traffic barrier
of support (eg piers, abutment).
supports the superstructure at its extremities
Parapet – low protective concrete
and retains earthworks.
wall at edge of bridge deck.
Spill through abutment – an abutment which
Railing – on top of parapet to
allows fill to form a slope into the end span
restrict lateral movement of traffic.
rather than retaining it with a face wall.
01 | Introduction
Bridge Aesthetics
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Introduction
Plank bridges – bridges which utilise a simple concrete plank
Haunching – increase in the depth of a continuous beam at the
and cross support construction system.
point of support to withstand the increased moment of
bending on the beam.
Planks – structural units.
Parapet – (outer face).
Bearing – a component which supports part of the bridge and which transmits
forces from that part to another part of the structure whilst permitting angular
and/or linear movement between parts.
Safety Screen.
Pedestrian barrier – a railing
Pier Cap / Headstock – a component
Beam / Girder – load bearing
placed on edges of bridge
which transfers loads from the
member which supports the deck.
structure for pedestrian safety.
superstructure to the piers.
[8]
Bridge Aesthetics
Introduction | 01

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