Cowra Truss Bridge, Lachlan River

The first bridge constructed at this site was an American all-timber McCallum truss bridge of three spans. It existed from 1868 until replaced by a bridge designed by John A McDonald.

The McDonald bridge was the first in New South Wales to use a composite timber-iron truss and was the largest of its type in Australia. The bridge carried the busy north-south inland road traffic for 93 years until 1986, when it was replaced.

In 1990 one of the McDonald truss spans that had been erected in Bryant Park, was awarded an Historic Engineering Marker plaque by The Institution of Engineers, Australia. However, it was demolished in 1999 because it had become unsafe. In 2002 a new inerpretation panel was installed by Engineers Australia, more relevant to the site without the preserved truss.

The existing seven span bridge comprises two prestressed concrete continuous box girders. It was designed by the then Department of Main Roads and opened in 1986.

John McDonald came from England. He joined the Department of Public Works NSW in 1879 and from 1889 to 1893was Engineer for Bridges. McDonald made a significant contribution to bridge design in NSW. His achievements include redesign in 1886 of the standard PWD trust to produce the “McDonald Truss”, design of all five lattice-girder road bridges from 1884, design c. 1884 of a series of sliding bridges at Lismore, Coopernook and Erina, and design of early bascule and lift bridges, such as over the Darling River at Bourke in 1883. McDonald died in 1893.

Cowra road truss bridge acros the Lachlan River.

Second interpretation panel installed after demolition of preserved span.

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Cowra Truss Bridge, Lachlan River location map.

EA Sydney Divison President Bruce Howard at the unveiling of the second interpretatin panel in 2002.

A preserved section of a concrete filled iron pier adjacent to the panel in 2002.

Engineering Heritage Recognition Program

Marker Type	Historic Engineering Marker (HEM)
Award Date	1990 and 26 October 2002
Heritage Significance	This span was the first composite timber / iron truss in New South Wales and was the largest of its type in Australia.
Nomination Document	Available here.
Ceremony Booklet	Available Here.
Plaque/Interpretation Panel	Available Here.
Original Plaque	Available Here.