The Eleanor Schonell Bridge, Brisbane

concrete concepts
03
concrete – the responsible choice
thermal mass
impact-resistance
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The Eleanor Schonell Bridge over the Brisbane River
low-maintenance
non-toxic
termite-proof
cost-effective
The Eleanor Schonell
Bridge, Brisbane
The Eleanor Schonell Bridge provides an excellent
example of concrete used to provide sustainable
infrastructure. The new key public transport crossing
of the Brisbane River demonstrates a balanced
response across the three pillars of sustainable
development: social, environmental and economic1.
For more information on sustainable development,
see CCAA’s publication Concrete the Responsible
Choice2.
A sustainable infrastructure project
The Eleanor Schonell Bridge represents an important
milestone in sustainable infrastructure, being the
first bridge in Australia designed specifically for the
enhancement of a public transport system (buses)
and the encouragement of other green modes of
transport (walking and cycling).
This new river crossing significantly benefits the
environment and the broader community, by
encouraging environmentally responsible modes
of transport and reducing congestion on the CBD
feeder roads.
The bridge is a dedicated bus corridor, with two-lanes
each way. There are separate pedestrian and cycle
lanes that link the University of Queensland (UQ)
at St Lucia with the cross-river south-side suburbs.
Located approximately one kilometre from Annerley
Road at Dutton Park, this vital river crossing provides
a new public transport link for Brisbane’s second
largest traffic generator after the Brisbane CBD.
A key transport objective was to ease congestion
on Coronation Drive, a major arterial road that feeds
both the CBD and the University. The recent removal
of the T3 lane from Coronation Drive is a clear
indication that this objective has been achieved. It
has been so successful that additional bus services
were initiated to cope with the increased demand just
months after opening.
Aesthetics
The outline design aimed to create an experience
rather than a journey, by complementing and
not dominating the bridge’s surroundings. This is
achieved through the use of slender towers and a
slender composite bridge deck. It was important
to achieve continuity of the colour of the finished
concrete.
Two measures were taken to ensure continuity and
consistency of colour. Firstly, the concrete supplier
ensured that all cement, sand and aggregates were
taken from a single source over the six month period
during which the towers were constructed. Secondly,
the concrete slump was tightly controlled through the
use of water-reducing admixtures (plasticisers) and
no water was allowed to be added to the concrete to
adjust the slump on site.
Economy
The Eleanor Schonell Bridge is recognised as
providing excellent value-for-money for the Brisbane
community. Through a range of value engineering
initiatives, the project team achieved a total of
$17 million cost savings relative to the initial
tender price.
Durability
Judicious material selection will contribute to the
longevity of the bridge. Through the use of highly
durable materials, and the implementation of a
detailed asset management programme, it is
anticipated that the bridge’s life be extended from
100 to beyond 150 years.
Dedicated pedestrian and cycle paths on the bridge
To meet the long-term durability requirements for
the structures in the river tidal zone, the chloride
resistance of the precast concrete permanent
formwork ‘boats’ and skirt panels for the pile cap
was given particular consideration. The fly ash
incorporated into the mix for this purpose also acts
as a cement replacement, reducing the carbon
footprint of the concrete.
Stainless steel reinforcement was specified in
the tidal zones to further enhance the corrosion
resistance.
Innovative use of concrete
Critical to the performance of the bridge deck is its
ability to act, as designed, as a composite structure.
For the best results, this meant limiting the shrinkage
in the precast concrete panels of the bridge deck
and in the insitu concrete strips between them. The
designers therefore specified that the precast panels
be manufactured from low-shrinkage concrete, and
cured for a minimum of 60 days before incorporation
into the bridge deck. The concrete supplier, Boral,
conducted rigorous testing in the laboratory and on
site, to ensure a high level of quality control.
Sustainable design
The name ‘Green Bridge’ was originally adopted
for the project, implying a strict adherence to
environmental and sustainable principles in the
design and construction. During the preliminary
design, environmental and materials engineers
investigated potential environmental initiatives, such
as the reuse of stormwater, minimum environmental
impact during construction and energy regeneration.
This approach to the design resulted in some of the
key features adopted in the project:
n
Installation of a solar roof structure for green
energy generation
n
Minimised energy consumption for lighting
n
Collection, treatment, and reuse of stormwater in
the university irrigation system
n
Use of high-durability concrete, with significant
cement replacement by fly ash
n
Use of high-strength concrete to minimise the
required volume.
n
Improved labour efficiency.
Solar energy generation The Eleanor Schonell
Bridge was designed and constructed to be energy
neutral. The energy requirement of the bridge is
met by a high profile solar roof, containing over
a hundred 175-W panels. The solar roof feeds
electricity back into the supply-authority grid, thereby
offsetting the mains electricity used by the bridge at
night. This roof is located at a prominent position in
Dutton Park to maximise visibility and help promote
renewable energy. A unique feature of the solar roof
is the real-time public display of the solar generation
performance, which shows just how much energy the
roof generates, and how much energy is consumed
by the bridge and its systems.
Reduced energy consumption To minimise
consumption, energy-efficient, low-wattage lights
were used. Feature lighting was also minimised to
reduce both power requirements and the visual impact
of the bridge on the surrounding area. Cut‑off timers
and remote operation features were also incorporated
to reduce the amount of unnecessary lighting while
still maintaining a safe environment for users.
Water recycling An innovative and proactive
approach to rainwater harvesting was taken.
Runoff from the bus-way and bridge is captured
and channelled through a triple interceptor and
bio‑retention basin at UQ before discharging into
the UQ lake system, where it is ultimately used for
irrigation of the UQ grounds.
top: The solar roof structure and slump testing on site
centre: Installation of the precast concrete deck panels
above: Construction of the towers
Precasting some of the key components improved
the efficiency by reducing onsite labour activities and
associated costs. This also ensured a high quality of
finish.
Construction of the pile caps
High-durability concrete incorporating fly ash
The materials used in the construction of the bridge
were chosen with long-term sustainability in mind.
The overall volume of materials was reduced to
the absolute minimum by several rounds of value
engineering. The concrete mix incorporated silica
fume to gain the necessary strength, as well as to
provide a high level of chloride resistance in the
aggressive marine environment. In addition, fly ash
was used as a component of the overall cementitious
content. Excellent strength results were achieved
throughout the tower construction.
High-strength concrete To deliver the desired
sleek and elegant look desired by the project
team, the tower elements were kept to a minimum
cross‑section by using high-strength concrete.
www.ccaa.com.au/sustainability
Improved labour efficiency The bridge deck is
made up of 492 precast concrete panels, from
which 164 unique types were identified. Each panel
was approximately 5 m x 3.5 m, weighed around
10 tonnes and was designed for a specific location
on the deck.
The development of precast ‘boats’ enabled
uninterrupted construction of the pile caps in the tidal
zone of the river. Each ‘boat’ consisted of six precast
units that were produced on shore before being
placed in the river. To minimise the risk of thermal
cracking, concrete with low heat of hydration was
used for the large mass pours for the pile caps.
Summary
The Eleanor Schonell Bridge over the Brisbane
River is a good example of social, environmental
and economic sustainability. Completed two
months ahead of schedule, within budget and
with exceptional quality, it is an excellent outcome
resulting from a collaborative team with a clear
sustainability vision – an excellent example of
sustainable concrete infrastructure.
References
1 2007 Public Domain Awards Cement Concrete
& Aggregates Australia, The Eleanor Schonell
Bridge (Bridges and Sustainable Design
Categories).
2 Concrete – the Responsible Choice Cement
Concrete & Aggregates Australia, 2010.
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