Built in 1895, Tharwa Bridge is the oldest standing bridge in the ACT and is the oldest surviving Allan Truss bridge in Australia. In 1983, the Australian Heritage Commission entered it on the Register of the National Estate and in 1998, it was entered on the ACT Heritage Register.
In 2005 it was closed when a routine inspection identified extensive wood rotting of a number of critical, structural elements of the bridge
The decision to restore the existing bridge to its original form, as opposed to building a new concrete bridge, followed an extensive community consultation process carried out in 2008. Endorsed by the ACT Heritage Council a conservation management plan was developed to guide the conservation and restoration of the bridge to ensure it remained consistent with the original design.
Arenco was responsible for the erection of a steel beam underslung assembly to the 4 truss span sections, each over 27 metres long, to support the deck whilst new trusses were fabricated.
Additional works included temporary supports to the pier crossheads, removal of the existing Allan Truss members, removal of existing Bailey panels, inspect and replace deteriorated cross girders and stringers and provide new traffic barriers and kerb for the bridge deck.
The bridge site is over the Murrumbidgee River and required a portion of the river to be temporarily filled to provide a suitable working platform. An approval was sought and obtained by the relevant local environmental authority and the works completed without incident and the bridge then re-opened for light traffic.
