Tharwa Bridge

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Tharwa Bridge
Tharwa Bridge April 2012.JPG
Tharwa Bridge is an Allan truss bridge over the Murrumbidgee River (looking North)
Crosses Murrimbidgee River
Designer Percy Allan
Design truss
Material timber
Load limit 5 tonnes
Constructed by McClure Bros
Inaugurated 27 March 1895
Coordinates Coordinates: 35°30′29″S 149°04′12″E / 35.508°S 149.07°E / -35.508; 149.07

Tharwa Bridge is a four span Allan truss bridge which provides a high-level crossing point across the Murrumbidgee River, allowing traffic between Canberra and Tharwa village. It is the oldest surviving bridge in the Australian Capital Territory.

History[edit]

Construction of Tharwa Bridge 1893

The bridge was opened on 27 March 1895, and a public holiday was declared in the region.[1] A parade was held in Tharwa and 1500 people watched Mrs Elizabeth McKeahnie (the oldest resident of the area) open the bridge.[2] The deck level of the bridge was based on the highest recorded flood level prior to building the bridge. A flood has not overtopped the bridge since construction. There is a mark on the concrete pier on the Western side of the river showing the flood level in 1991.

Heritage[edit]

Tharwa Bridge and the Murrumbidgee River after rain, 2005 (looking South); Tharwa is to the right.

The bridge was entered in the ACT Heritage Register [3] in 1998, is listed by the National Trust of Australia (ACT) and was entered on the Register of the National Estate by the Australian Heritage Commission in 1983.

The bridge has also been identified by Engineers Australia as a Major Engineering Heritage item [4] and is one of the most significant pieces of heritage in the Australian Capital Territory.

The Tharwa Bridge and its site are historically and technically significant because of the Allan truss structure, having form and structural integrity which have survived virtually intact. It is the archetypal example of the application of the new technology by Percy Allan to the construction of timber road bridges in New South Wales during a major development phase for bridge and road construction during the last decade of the nineteenth century.[5]

Tharwa Bridge is highly valued by the local community as an integral part of the village of Tharwa. It continues to contribute in social, economic and aesthetic terms to the community. The bridge and its site have associative significance with the period of nineteenth century European settlement and development of the region.

2005 closure and restoration[edit]

Looking at the Tharwa Bridge, showing the single lane

An engineering assessment of the bridge was undertaken in 1978 by structural engineering firm Hardcastle & Richards, which resulted in some upgrades. however, the bridge subsequently deteriorated.[6]

The bridge was closed in April 2005 when a routine inspection identified extensive wood rotting (caused by termites) of a number of critical, structural elements of the bridge. During July and August 2005, Tharwa Bridge was strengthened with bailey panels to provide a temporary crossing for vehicles up to five tonne. This arrangement was to have been in place until 2008, however, in September 2006 ACT Roads advised that the Tharwa Bridge would be closed for three months, and later announcing the bridge was to be closed for an indefinite period. Barriers were put in place to close off the bridge to road, cycle and pedestrian traffic. Traffic for was diverted north to Point Hut low level crossing. In the event of that crossing being closed due to flooding, the only other high level bridge in the area is at the Cotter.

In October 2006 the ACT Government announced its decision to construct a single lane concrete bridge with a pedestrian walkway adjacent to the existing bridge. Construction was intended to begin in 2007, however this plan was abandoned in favour,[7] of a decision to restore the old bridge, with construction getting underway in April 2008.

The bridge was reopened in August 2008 to light traffic less than 5 tonnes.[8]

The second phase of the project was completed in February 2010 with the foundations improved to withstand major flooding. The third and final phase of the restoration involved further closure of the bridge to public use to allow for replacement of the timber trusses, new timber deck, and steel railings.[9] The bridge was re-opened to the public on 24 June 2011,[10][11] with work ongoing and scheduled for completion in September 2011.[12]

See also[edit]

References[edit]

  1. ^ "Queanbeyan Borough Council". Queanbeyan Age. 16 Mar 1895. p. 2. Retrieved 26 October 2010. 
  2. ^ Exploring the ACT and Southeast New South Wales, J. Kay McDonald, Kangaroo Press, Sydney, 1985, p46 ISBN 0-86417-049-1
  3. ^ "20036. Tharwa Bridge". Chief Minister's Department. 
  4. ^ "REGISTER OF ENGINEERING HERITAGE MARKERS". Engineers Australia. Retrieved 28 October 2010. 
  5. ^ "Legislative Assembly for the ACT: 1998 Week 7 Hansard (22 September), p. 2016". ACT Government. 1998. Retrieved 2006-10-25. 
  6. ^ Tharwa Bridge feasibility study National Capital Development Commission, 1978
  7. ^ "New Bridge for Tharwa". Roads ACT. 2006. Retrieved 2006-10-25. 
  8. ^ "Tharwa Bridge to reopen today for light traffic". Canberra Times. 2008. Retrieved 2009-03-18. 
  9. ^ /MR77_0211_Tharwa_Bridge_Restoration_in_its_final_stages.pdf Tharwa Bridge closed for final stages of work, 15 March 2011, Territory and Municipal Services, ACT
  10. ^ Restored Tharwa Bridge reopening, 24 June, 2011, ABC Online
  11. ^ Historic Tharwa bridge restored and re-opened, 24 June 2011, The Canberra Times
  12. ^ "Tharwa Bridge opened". Canberra Times. 9 February 2010. Proquest document id 1957809231. 

External links[edit]