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The road has a long history of instability between Clifton and
Coalcliff, resulting in road closures, sometimes for months at a
time. Initially constructed in the 1860's, this road was known as
the Lower Coast Road until 1947, when it was renamed
Lawrence Hargrave Drive after the famous Aviator Lawrence Hargrave and the first Australian to fly at the nearby Stanwell
Park.
Many attempts have been made over the years to maintain the
road in an open condition, none with long-term success. During
2003 major cracks approaching 1 metre wide developed and
significant repairs became necessary. A maintenance resolution
was not possible, and with the road posing a risk to public
safety, a long-term answer was required.
In August 2003 then Minister for Roads announced the closure
of Lawrence Hargrave Drive for two and a half years to enable
a more permanent solution to be constructed. In a first for the
Roads and Traffic Authority (RTA) of NSW, the Lawrence
Hargrave Drive (LHD) Link Alliance formed between the RTA,
Barclay Mowlem Construction Limited, Maunsell Australia and
Coffey Geosciences. The Alliance enabled the rapid and
effective completion of the challenging $49 million construction
project, with conventional methods likely to have taken
considerably longer and added to community dislocation and cost.
No Bridge too far
The goal of this ambitious project was to provide a fully available
road with a design life of 100 years. Two bridges were built concurrently with the Lawrence Hargrave Drive structure
comprised of a 5 span 450m long Balanced Cantilever Bridge
(BCB) adjoining a 7 span 203m long Incremental Launched
Bridge (ILB), sharing a common pier. Standing in the Pacific
Ocean in places and up to 70m east of the original alignment, the Balanced Cantilever and Incremental Launch Bridges incorporate
2 traffic lanes of 3.5 to 3.8m, 2 x 1m wide shoulders and a 2.5m
shared pathway on the eastern side.
A Sizeable Challenge
Boral Country Concrete & Quarries were instrumental in the construction, design and supply of concrete to the Lawrence
Hargrave Drive Bridge project. Their greatest challenge was to
produce a high performance, consistent and durable concrete
that enabled the rapid construction of the bridge structure in a
harsh exposed coastal environment with limited space (a narrow cliff-edge road) on site.
Future maintenance of the road structure was a consideration of
the project and needed to be minimised by careful detailing and
quality construction. Chloride induced corrosion is the most
serious cause of deterioration in reinforced concrete structures.
Two key features - quality concrete and cathodic protection -
were therefore integrated into the design and construction of the
bridge structures to maximise durability.
Boral Quality Concrete
Good quality concrete was essential for this project, requiring an optimum balance of durability and timely construction. To achieve
this Boral Country Concrete & Quarries erected an on-site
concrete batch plant to supply the project with a refined mix
consisting of Boral Cement Shrinkage Limited
cement (approximately 5,000 tonnes) and fly ash (1,000 tonnes).
Boral Cement Shrinkage Limited cement was
crucial in achieving the required shrinkage tolerances and
strengths for the bridge structures. Consequently, Boral
delivered a workable, durable, high quality and consistent
concrete that met the specified performance and produced a
superior finish, far exceeding expectations. Take the coast road
next time you are driving through Clifton, NSW and see for
yourself.
More information on the Lawrence Hargraves Drive Bridge
project:
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