Duplex stainless steel forms an integral part in creating one of Sydney’s most exciting new structures. Located in Macquarie Park, the cyclist bridge provides visual flair, safe accessibility, and excitement to the area.
The design is the first of its kind in Australia, utilising a double helix arrangement with a varying diameter along its curving 178m length. A steel truss arrangement is used, required for the long sections spanning the multiple roads below its footprint. The diameter of the spiral increases at the bridge supports and tapers along its span. At its narrowest, it is 5.5m in diameter, and 7.8m at its widest.
Approximately 170t of 2205 grade duplex stainless steel was used, along with around 220t of structural mild steel. Due to the large quantity of material required, multiple distributors supplied material mostly on an indent basis, with some delivered ex-stock. Midway Metals, Stirlings Performance Steels and Vulcan Stainless all supplied material, with the majority of plate (up to 80mm in thickness) produced by ASSDA Member Outokumpu, managed through their Melbourne office.
A minimum 100-year service life with minimal maintenance (becoming increasingly common in the design of bridges) was a key criterion, particularly important for the hard to access structural components. From the beginning, 2205 duplex grade presented as an ideal material, thanks to its hybridised microstructural properties granting it superior mechanical properties to many forms of mild and stainless steel.