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The upgrade of the Pacific Highway between Hexham in NSW and the Queensland border is one of the largest road infrastructure projects in NSW, making major improvements to road conditions, increasing safety and reducing journey times between Sydney and Brisbane.
The Macleay River and Floodplain Bridge, is a 3.2km road bridge that extends over a floodplain and crosses the Macleay River. The bridge forms part of the overall Kempsey Bypass project; a 14.5km four-lane divided highway which bypasses the towns of Kempsey and Frederickton.
The bridge, delivered under a Design and Construct Contract, was designed using advanced structural and geotechnical modelling techniques producing an innovative and more efficient bridge structure that reduced the diameter of the 324 steel piles and removed the need for pile caps. This simplified the construction process and provided significant savings to construction costs. This innovative solution also minimised excavation works on the floodplain, which reduced the risk of producing acid sulphate soil which is a high risk in this region of NSW, reducing the impact on the environment and construction costs.
Arup collaborated with the principal client Roads and Maritime Services and Abigroup Contractors (now Lend Lease Engineering) in delivering the design solution and design innovations that enabled the bridge to be completed three months ahead of schedule, despite a number of significant flood events occurring during construction.
This simplified the construction process and provided significant savings to construction costs. This innovative solution also minimised excavation works on the floodplain, which reduced the risk of producing acid sulphate soil which is a high risk in this region of NSW, reducing the impact on the environment and construction costs.
Arup collaborated with the principal client Roads and Maritime Services and Abigroup Contractors (now Lend Lease Engineering) in delivering the design solution and design innovations that enabled the bridge to be completed three months ahead of schedule, despite a number of significant flood events occurring during construction.
After almost 12 years of working closely with the community, Kempsey Shire Council, government agencies and contractors, it has been great to deliver such an important part of the highway upgrade, and it was completed all within budget, in a shorter delivery time and at a higher standard than initially envisaged. It is a much better outcome for the community and road users with the longer bridge.
Design of the bridge commenced in December 2010 with construction started in July 2011. Work was completed in December 2012 with the Kempsey Bypass opening to traffic in late March 2013 for the Easter holiday traffic. The Macleay River and Floodplain Bridge is Australia’s longest road bridge.
The amount of drainage on the bridge was also minimised which both improved the aesthetics of the structure and reduced future maintenance requirements. Whole of life costs were reduced through the provision of free draining scuppers which are a low maintenance solution.
A water quality strategy which treated stormwater runoff from the bridge using swales within the floodplain was also developed in collaboration with environmental agencies and surrounding landowners. Physical scale modelling was completed to support bridge scour assessment which resulted in considerable savings to the pile design and construction programme.
