Bridges

A new pedestrian cable stay bridge (twin cell box steel girder) with complex curved geometry and asymmetric cable supports was required to be constructed over Footscray Road (a major arterial road in Victoria). As such construction solutions designed to minimise traffic disruption were required. The superstructure was delivered to site in 6 pieces to accommodate available lifting equipment. The complicated geometry of the bridge combined with the temperature impacts on steel, posed challenges in connecting the steel pieces to tolerance. The ground conditions of the site comprise Coode Island silt known for its high settlement properties. Temporary towers supporting the superstructure had to be designed to accommodate this settlement and provide the necessary restraint to ensure stability of the bridge works throughout construction.

This paper details the construction sequence designed to ensure stability of the structure during all stages of erection and ensure no overstressing of permanent works. It details the associated temporary works design, detailed to incorporate features to allow girder repositioning such that girder pieces could be connected to tolerance in light of the high settlement ground conditions and temperature effects. It summarises the unforeseen construction challenges which arose during installation and the solutions developed; as well as the monitoring and adjustment works to achieve the required civil alignment and stress in the permanent works at the end of the build.