Banora Point upgrade: Twin Viaducts over valley

The Twin Viaducts form part of the Banora Point Upgrade. The viaducts were located within geometrically complex road alignment and restricted project boundary. The substructure arrangement of the Twin Viaducts comprises 35 degrees skewed abutments, staggered hammer head piers and combined portal frame piers, ranging up to 25 m in height. The girders were supported by laminated elastomeric and hybrid frictionless elastomeric bearings. Furthermore, the Twin Viaducts have been analysed with an earthquake response factor (Rf) of 2.0 in accordance with AS5100.2-2004. As a result, the ductility reinforcement was omitted in the substructure. In order to minimise reinforcement tack welding due to provision of cathodic protection, the reinforcement in pier column and headstock was isolated from cathodic protection connection. All pier columns were built using repetitive jump-form construction methodology. The pier headstocks were cast using elevated steel beam falsework which was supported by the pier columns. The proposed bridge articulation and substructure forms were structurally efficient and has demonstrated substantial cost saving.