Transmission Gully

Bridge 20 is the largest and most technically demanding structure on the 27‑kilometre Transmission Gully motorway, a four‑lane route connecting Mackays Crossing to Linden with four new interchanges and two link roads. Standing 60 metres above the stream below, the bridge spans 226 metres across three spans (72.4 m – 86 m – 67.9 m) and carries four lanes of traffic. Its deck is formed by 44 steel girders, each 1.8 metres wide and 3 metres deep, supported by two abutments and two piers. Due to its scale and geometry, Bridge 20 required a highly specialised incremental launch methodology and extensive temporary works to safely position the superstructure.