Heritage and conservation register
|Name of Item||Bridge over Turon River at Wallaby Rocks|
|Type of Item||Built|
|Item Sub-Type||NSW Allan Truss Bridges|
|Address||**** Regional Road 216 Sofala (West) 2795|
|Local Government Area||****|
|Current Use||Road bridge|
|Former Use||Road bridge|
Statement of significance
|Statement of significance||Completed in 1897, the Turon River bridge is amongst the oldest examples of an Allan type timber truss road bridge, and in 1998 was in good condition.
As a timber truss road bridge, it has strong associations with the expansion of the road network and economic activity throughout NSW, and Percy Allan, the designer of this type of truss.
Allan trusses were third in the five-stage design evolution of NSW timber truss bridges, and were a major improvement over the McDonald trusses which preceded them. Allan trusses were 20% cheaper to build than Mc Donald trusses, could carry 50% more load, and were easier to maintain.
The bridge has iron piers, which is a rare technical and aesthetic feature, and has the ability to demonstrate much about the manufacturing technology of the late 19th century.
In 1998 there were 38 surviving Allan trusses in NSW of the 105 built, and 82 timber truss road bridges survive from the over 400 built.
The Turon River bridge is a representative example of Allan timber truss road bridges, and is assessed as being State significant, primarily on the basis of its technical and historical significance.
|Date Significance Updated||10 February 1999|
|Builder||E Taylor, Balmain|
|Construction years||**** - 1897|
|Physical description||Wallaby Rocks Bridge is an Allan type timber truss road bridge. It has 3 timber truss spans, each of 27.7m (91ft). There are 2 approach spans at one end and one at the other giving the bridge an overall length of 106.7m (350ft).
The timber truss spans are supported by painted twin cast iron cylindrical piers. The approach spans are supported by timber trestles. The bridge provides a single lane carriage way with a minimum width of 4.6m. A post and rail timber guard rail extends the full length of the bridge.
|Original condition assessment: 'Good' (Last updated: 22/10/1998.) 2007-08 condition update: 'Poor .' (Last updated: 17/4/09.)|
|Modifications and dates||****|
|Date condition updated||17 April 2009|
|Historical notes||The Turon River bridge is an Allan type timber truss road bridge and was completed in 1897.
Timber truss road bridges have played a significant role in the expansion and improvement of the NSW road network. Prior to the bridges being built, river crossings were often dangerous in times of rain, which caused bulk freight movement to be prohibitively expensive for most agricultural and mining produce. Only the high priced wool clip of the time was able to carry the costs and inconvenience imposed by the generally inadequate river crossings that often existed prior to the trusses construction.
Timber truss bridges were preferred by the Public Works Department from the mid 19th to the early 20th century because they were relatively cheap to construct, and used mostly local materials. The financially troubled governments of the day applied pressure to the Public Works Department to produce as much road and bridge work for as little cost as possible, using local materials. This condition effectively prohibited the use of iron and steel, as these, prior to the construction of the steel works at Newcastle in the early 20th century, had to be imported from England.
Allan trusses were the first truly scientifically engineered timber truss bridges, and incorporate American design ideas for the first time. This is a reflection of the changing mindset of the NSW people, who were slowly accepting that American ideas could be as good as or better than European ones. The high quality and low cost of the Allan truss design entrenched the dominance of timber truss bridges for NSW roads for the next 30 years.
Percy Allan, the designer of Allan truss and other bridges, was a senior engineer of the Public Works Department, and a prominent figure in late 19th century NSW.
Timber truss bridges, and timber bridges generally were so common that NSW was known to travellers as the "timber bridge state".
|Heritage Listing||Reference Number||Gazette Number||Gazette Page|
|Heritage Act - State Heritage Register||01458|
|Heritage Act - s.170 NSW State agency heritage register|
|National Trust of Australia register|
Assessment of Significance
|Historical Significance||Through the bridge's association with the expansion of the NSW road network, its ability to demonstrate historically important concepts such as the gradual acceptance of NSW people of American design ideas, and its association with Percy Allan, it has historical significance.|
|Aesthetic/Technical Significance||The bridge exhibits the technical excellence of its design, as all of the structural detail is clearly visible. In the context of its landscape it is visually attractive, and the large three main span construction is an imposing presence. As such, the bridge has moderate aesthetic significance.|
|Social Significance||Timber truss bridges are prominent to road travellers, and NSW has in the past been referred to as the "timber truss bridge state". Through this, the complete set of bridges gain some social significance, as they could be said to be held in reasonable esteem by many travellers in NSW. The Turon River Bridge is held in some esteem by the people of Bathurst, and contributes in a small way to the heritage tourism which is popular in the area.|
|Research Significance||The bridge is highly technically significant because it is a, example of an Allan truss, and is representative of some major technical developments that were made in timber truss design by the Public Works Department. The bridge has iron piers, which is a rare technical and aesthetic feature, and has the ability to demonstrate much about the manufacturing technology of the early 20th century.|
|Rarity||Rare - In 1998 there were 38 surviving Allan trusses in NSW of the 105 built, and 82 timber truss road bridges survive from the over 400 built.|
|Representativeness||Representative of Allan truss bridges|
|Written||Fraser, D J||1985||Timber Bridges of New south Wales|
|Written||Allan, Percy||1924||Highway Bridge Construction. The practice in New South Wales|
|Written||Depratment of Main Roads, NSW||1987||Timber Truss Bridge Maintenance Handbook|
|Title||Year||Author||Inspected by||Guidelines used|
|Relative Heritage Significance of all Timber Truss Bridges in NSW||1998||McMillan Britton & Kell||Yes|
|Roads and Maritime Services Region||Western|
|CARMS File Number||General File: 146.112 Dubbo District Office Bridge File: B1185|
|Conservation Management Plan||In preparation - Hughes Trueman Reinhold - CMP expected March 2000 - contact Dave Manchanayake, Western Region|