Heritage and conservation register

Item

Name of Item Bridge over Turon River at Wallaby Rocks
Item Number 4300155
Type of Item Built
Item Sub-Type NSW Allan Truss Bridges
Roadloc  
Address **** Regional Road 216 Sofala (West) 2795
Local Government Area **** 
Owner Local Government
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

 

Description

Designer Percy Allan
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.

Physical Condition
and/or
Archaeological Potential
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

 

History

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".

 

Listings

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.
Historical Association ****
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.
Representativenes Representative of Allan truss bridges
Integrity/Intactness Intact
Assessed Significance State

 

References

 

Type Author Year Title
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 

 

Study details

Title Year Author Inspected by Guidelines used
Relative Heritage Significance of all Timber Truss Bridges in NSW  1998  McMillan Britton & Kell    Yes 

 

Custom fields

Roads and Maritime Services Region Western
Bridge Number 1185
CARMS File Number General File: 146.112 Dubbo District Office Bridge File: B1185
Property Number Bridge
Conservation Management Plan In preparation - Hughes Trueman Reinhold - CMP expected March 2000 - contact Dave Manchanayake, Western Region

 

Images

Bridge over Turon River at Wallaby Rocks
Bridge over Turon River at Wallaby Rocks

General view of the bridge showing the timber trusses and painted iron piers
General view of the bridge showing the timber trusses and painted iron piers