Denison Bridge
Denison Bridge
Significance
The Denison Bridge was built in 1870, replacing an earlier 1856 bridge which connected the first settlement of Bathurst on the Kelso side of the Macquarie River – Wambuul with what is now the Bathurst CBD.
The bridge is a prominent local landmark which has played an important role in the history of Bathurst and the Central West. The structure proved the capabilities of colonial engineering skills given that the bridge remains in good condition some 150+ years later.
Vehicular crossing over the river was replaced by the Evans Bridge in 1993, and the Denison Bridge was converted to a footbridge.
[Source: Denison Bridge Bathurst, Macquarie River ~ 1885, by W.C Bennett, Monkerai Bridge CMP 2020]
Brief History
On 5th May 1815, Governor Macquarie proclaimed the settlement of Bathurst on the western side of the Macquarie River – Wambuul. In 1821, the new Governor, Thomas Brisbane, issued new land grants and grazing permits allowing intensive settlement to begin. Any free settler issued land on which to live had to build east of the river until such time as the river could be crossed.
With the settler population of Bathurst slowing starting to grow, the town was surveyed and declared a ‘provincial town’ in 1833. In 1856, following the gold rush, the first bridge over the Macquarie River – Wambuul was opened by, and named after, the Governor, Sir William Denison. The timber bridge was washed away in the floods of 1867. A replacement bridge was imperative.
The iron bridge was constructed in 1869 to 1870 and was opened in June 1870 when the Governor, Early of Belmore, crossed it in his carriage.
Engineers Behind The Design
The bridge design is associated with two important colonial engineers: William Christopher Bennett, and Gustavus Alphonse Morrell.
The supervisor of the original bridge design was engineer, William Christopher Bennett. Bennett came from Ireland where he worked on railway and drainage works, and in South America on canal works. Arriving in Sydney in 1855, he joined the Department of Roads which he helped to form and eventually was appointed Commissioner for Roads on 1st November 1862.
The bridge designer, Gustavus Alphonse Morrell, arrived in Australia in 1863 and worked for the Public Works Department as an engineer. He was appointed Assistant Engineer on 13 June 1867. He was a founding member of the Engineering Association of New South Wales formed on 24 September 1870.
Under Bennett, Morrell assisted in the design of the bridge. It was the first time Morell used the American Pratt truss system, and the first time it was used in NSW, marking a break from contemporary British technology. Morell and Bennett’s signatures appear on the bridge contract drawings which can be seen below.
[Source: Nomination of the 1870 Denison Bridge as an Historic Engineering Marker, Nov 1994, p46]
Bridge Builders
The engineering firm P.N. Russell & Co constructed the Denison Bridge at a cost of 18,818 pounds.
After success in establishing engineering works firms in Sydney, in 1855 Peter Nicol Russell established P.N. Russell & Co with his father and brother. The firm flourished, establishing workshops on a large waterfront area at Darling Harbour and by the 1870s employing 850 men. During this period, the firm completed the contracts for the Denison Bridge as well as the Hume Bridge at Yass in 1871.
Design Details
The bridge consists of six approach spans of 6.7m, three on each side of the river. The truss spans are of length 34m, 34.5m, and 34m; and have a deck width of 6.1m. The clean, open arrangement of members and joints makes for easy maintenance.
The three trusses are supported on pairs of braced, 1.83m in diameter cast iron cylinders, which are founded on rock. The internal truss members are the tension diagonals – strips of flat iron, braced regularly to dampen vibration. The internal compression members are four sections of angle iron, strongly braced together, at the corners of a rectangle.
Morell’s use of the ‘I’ beam horizontally is structurally very efficient and is an elegant design feature; his design was years ahead of the theoretical solution.
[Source: Nomination of the 1870 Denison Bridge as an Historic Engineering Marker, Nov 1994, p41)
The cross section of the beam creates a capital letter ‘I’ shape as shown on the above image.
For more engineering details, access the Engineering Australia website here.
Heritage Recognition
The Bridge is listed as a state heritage item on the NSW State Heritage Register and as an item of local and state significance on the Bathurst Regional Local Environmental Plan 2014. It is also within the Bathurst Heritage Conservation Area. It is listed in the National Trust register and in the State Heritage Inventory.
It was placed on the National Engineering Heritage Register in 1995.