Bridges

Sydney Gateway Stage 3 contains a 550m long Viaduct connecting the upgraded Qantas Drive with Sydney Airport domestic arrival and departure terminals. This paper will give an overview of some of the interesting and less conventional aspects of its design.

The Viaduct marks the entrance to Sydney's domestic airport with the piers and bridge superstructure very prominent to motorists travelling to and from the airport. It snakes along Qantas Drive before making a sharp turn over to Sir Reginald Ansett Drive where it bifurcates to become two separate superstructures for each terminal.

Restrictive geometric constraints for the alignment and substructure meant limited space is available for the pier columns and monopile/column piers in the road median was the only viable option. Precast headstocks were adopted to enable the headstocks to be constructed over and adjacent to the traffic lanes. Column capitals support the precast headstock in the temporary condition whilst being an urban design feature by integrating the headstock into the column to give the appearance of one pier element.

A combination of Super-Ts and composite steel girders is used for the superstructure. Super-Ts are applied where possible to simplify and minimise cost/maintenance. Two steel spans were required; a 56m simply supported span over an intersection and a 55m curved span which goes over the airport rail tunnel on a very tight 59m radius. At the curved span, the backspan Super-Ts, pier and steel girder are stitched together to form a monolithic integral continuous pier. A concrete infill inside the steel girder adjacent to the pier facilitates a reinforced concrete connection to the steel. The superstructure is clad with perforated backlit aluminium panels, incorporating Indigenous artwork, which are inclined to accentuate the curved alignment of the Viaduct.