Bridges

The paper will describe key technical elements of the Joy Baluch AM Bridge Duplication, constructed to bridge the upper Spencer Gulf in Port Augusta, SA. The 550m long bridge duplicates the 1970 structure, to provide badly needed additional traffic capacity for Port Augusta residents and to improve the Stuart (National) Highway.

The paper will focus on aspects of this major bridge project, which is part of a broader scope of works being delivered by the Port Wakefield to Port Augusta Project Alliance in SA. The elements to be described in detail within this paper are the new bridge piers and headstocks, upgrade and widening of the existing Joy Baluch bridge, and the shared path bridge over the ARTC rail line.

The new bridge piers consist of twin 1,200mm piles supporting concrete headstocks. Given the highly aggressive environment of the Upper Spencer Gulf and the challenges of inspection and maintenance, a bespoke approach was taken to the durability assessment. This resulted in a more considered assessment of the corrosion allowance than would be normal under the 'deemed to comply' approach embedded in AS5100.

The headstocks for the bridge were constructed using 'bathtub' precast shells, with in-situ cores. Given the safety implications of working over water, an integrated design development process with the construction team was necessary, with 1,200mm wide temporary walkways being incorporated.

The major upgrade and widening of the adjacent existing bridge, including a lightweight ìclip-onî Shared Use Path (SUP) improved pedestrian/cyclist connectivity. New traffic barriers were installed to bring the structure to current standards.

A clear spanning, concrete through-girder shared path bridge over the nearby ARTC rail line. This option proved superior to a more conventional Super-T approach in terms of geometry and barrier safety, with the girder web doubling as a traffic barrier for the adjacent road bridge.