Rakaia Gorge Bridge
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Rakaia Gorge Bridge | |
|---|---|
 Rakaia Gorge Bridge looking South, 2006 | |
| Coordinates | 43°31′3.71″S 171°39′26.27″E / 43.5176972°S 171.6572972°E |
| Carries | 1 lane of roadway |
| Crosses | Rakaia River |
| Locale | Canterbury, Windwhistle |
| Maintained by | Ashburton District Council, Selwyn District Council |
| Characteristics | |
| Design | Bollman Truss Bridge |
The Rakaia Gorge Bridge is located on the Rakaia River in inland Canterbury in New Zealand's South Island. The bridge connects the Selwyn and Ashburton districts and carries State Highway 77 and the Inland Scenic Route. It is one of only two bridges crossing the Rakaia River, with the other being the Rakaia Bridge, carrying State Highway 1.
The bridge is one of only two Bollman Truss Bridges anywhere in the world, and the only one still carrying vehicles. Construction was completed in 1882.
Description
[edit]The Rakaia Gorge Bridge follows a unique "Bollman Truss" bridge design seen in only one other bridge left anywhere in the world, the Bollman Truss Railroad Bridge. The design was patented in 1852 by Wendel Bollman, a United States railway engineer. The design involves a series of non-symmetrical trussed beams of iron being jointed to vertical members by hinged pins to facilitate construction, and more than 100 examples were constructed on railways such as the Baltimore and Ohio Railroad among others.[1][2] Regarding the design, Bollman wrote “This bridge has the advantage of great strength and perfect security, with very little weight of metal". The bridge design enjoyed great success for a number of years before it was superseded by more economic and effective bridge designs.
The Rakaia Gorge Bridge spans 57 metres and features a timber deck and handrail on top of it's iron girders and truss. The bridge is also thought to be one of the earliest wrought iron bridges in New Zealand, and one of the few 19th century components of the New Zealand state highway network.[3]
History
[edit]The Rakaia Gorge Bridge was constructed between 1880 and 1882 with the purpose of serving inland farmland and service towns following calls for a second bridge over the river after the construction of one near the river mouth in 1873. In 1877 the Public Works Department (PWD) concluded debate on the bridge and decided to move forward with construction of a single lane road traffic bridge with the opportunity to carry rail if needed. [3]
At the time of construction, the New Zealand Government had recently been centralised and the PWD restructured, resulting in several high profile engineers being involved in the design and construction. Involved engineers included the Canterbury Provincial Engineer George Thornton, John Carruthers, William Newsham Blair, and Peter Seton Hay. The bridge was constructed by W. H. Barnes of Oamaru.[3]
The bridge was registered as a historic place in 1980 under the Historic Places Act, and is currently categorised as a Category 1 Historic Place by Heritage New Zealand[1].
References
[edit]- ^ a b "Welcome to Heritage New Zealand". Welcome to Heritage New Zealand. Retrieved 16 July 2025.
- ^ Griggs Jr., Frank (February 2015). "Bollman Truss at Harper's Ferry". Structure. Retrieved 16 July 2025.
- ^ a b c "Rakaia Gorge Bridge | Engineering New Zealand". www.engineeringnz.org. Retrieved 16 July 2025.
External links
[edit]43°31′05″S 171°39′21″E / 43.5180°S 171.6557°E
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