Rakaia Gorge Bridge
Posted by: 
3l diesel
S 43° 31.062 E 171° 39.473
59G E 553170 N 5181482
The Rakaia Gorge Bridge is an example of New Zealand's ability to construct suitable road bridges and has been plaqued by the Institution of Professional Engineers, New Zealand (IPENZ).
Waymark Code: WM9PNF
Location: South Island, New Zealand
Date Posted: 09/15/2010
Views: 10
From the IPENZ heritage database, we read:
"
The Rakaia Gorge bridge is constructed of wrought iron in an unconventional form of trussed beam, unique in New Zealand and probably anywhere else. At one time this bridge was believed to be a 'Bollman' Truss and only the second one still in existence. This claim was clearly disproved in research carried out in 1989-90 on behalf of the IPENZ National Engineering Heritage Committee then based in Christchurch while it was being considered for an IPENZ plaque.
The bridge deck is supported by rivetted wrought iron plate girders with a depth of 1 metre. Three wrought iron columns with pin jointed raked tie rods provide a form resembling an inverted truss at first glance. The ties are anchored at both abutments by massive concrete anchors tunnelled into the rock walls of the gorge. The deck and balustrades are timber. The bridge span is 55 m and the height above the river level is 17 metres.
The Bollman Truss design was patented by Wendell Bollman of Baltimore USA in 1852 for use on the Baltimore and Ohio Railroad. There was considerable interest in the design which owes something to Squire Whipple's work on bridges and to Albert Fink, both American bridge engineers. The most likely designer of the Rakaia Gorge Bridge is John Carruthers, Engineer-in-Chief of the Public Works Department at that time. It was completed in 1882.
Reference:
G M Jones; “Rakaia Gorge Bridge – The truss that isn’t”. Proceedings of the 1st Australasian Engineering Heritage Conference held in Christchurch, 1994.
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This is one of two bridges crossing the gorge, the other being a reinforced concrete arch structure further to the west.
The IPENZ plaque may be found near the south eastern corner of the bridge.
Location:
Rakaia Gorge Road (State Highway 77) about 18km north of Methven.
Type of structure/site: Bridge
Date of Construction: 1882
Engineer/Architect/Builder etc.: John Carruthers, Public Works Department
Engineering Organization Listing: Other (specify in description)
Primary Web Site: [Web Link]
Secondary Web Site: [Web Link]
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