Tharwa Bridge is the oldest bridge in the ACT and the oldest remaining example of a bridge built in the Allan Truss Style. The bridge was entered into the register of the National Estate in November 1983.
The bridge was opened on Wednesday the 27th of March 1895. Prior to the construction of the bridge, other methods of crossing the river had been employed. Punts crossed the river at Lanyon and Uriarra and a wire bridge for taking sheep up to the high country had also been constructed across the river. Frequently though, normal traffic attempted to cross the river only be bogged in sand. The community was very excitement for opening the Tharwa Bridge accordingly a public holiday was declared for the event. Percy Allan from the NSW Public Works Department is the engineer responsible for the design of the Tharwa Bridge. A significant feature of the Allan Howe truss design was that the compression timbers ran diagonally and the tension members (the iron tie rods) ran vertically. The Allan truss design required minimal preparation of timber during construction, many features of timber trusses conducive to rotting were minimised and joints were simplified. Additionally, the separated double component members allowed for easy inspection of condition and enabled replacement of components without major disruption to traffic. Construction of the bridge
In 1984, to celebrate the Centenary of the bridges opening, major restoration was conducted. Roads ACT currently manages the maintenance of the bridge in accordance with Heritage values.
SMEC was Commissioned by the ACT Department of Urban Services to oversee the replacement of Around 600 wooden planks in the deck of the Single-lane Bridge to improve driving Conditions and safety. The Tharwa Bridge is Listed by the ACT Government for Preservation as an historical monument and All work had to be carried out in accordance With regulations governing use of appropriate Materials and retention of the original Structure and character of the bridge.
A key aspect of the project was consultation With the 180 residents of Tharwa village Concerning the restoration plans and the Alternative traffic arrangements for the six Weeks scheduled for closure of the bridge. This was undertaken through exhibitions and Public meetings. The work was actually Completed in only five weeks. During restoration the opportunity was taken To assess the structural elements of the Bridge and prepare a program for Replacement of major components of the Trusses and cross-girders. This work will Continue until about April 2002.
In July 2001 RTA Operations, South In July 2001, RTA Operations, South Wagga won a $235,000 contract from the ACT Department of Urban Services to replace the decking on the historic Tharwa Bridge over the Murrumbidgee River, south of Canberra. Built in 1895, it has 4 timber truss spans and is the oldest surviving Allan truss bridge in Australia. Norman Young, Bridge Works Supervisor, proposed improvements to the method of fixing the timber decking to the truss spans, which reduced the cost to the client Sam Millie, Works Manager Bridges in Wagga and Scott Barnes, Maintenance Engineer Bridges in Deniliquin, worked closely with the ACT Department of Urban Services on the traffic and environmental management plans. The crew completed the deck replacement in five weeks one week ahead of schedule and under budget minimising impacts on the residents of Tharwa. As a result, the ACT Department of Urban Services offered RTA Operations additional work on the bridge.
