Callender-Hamilton truss bridges
The Callender-Hamilton truss bridge was regarded as the most economical bridge of its time and was created by New Zealander Archibald Milne Hamilton (1898–1972).
Hamilton was born in Waimate, South Canterbury, and graduated with a Bachelor of Engineering (Civil) degree from Canterbury College (now the University of Canterbury) in 1924.
Hamilton first developed his bridge design in 1927 in Iraq, where he was working as their Public Works Department’s Assistant Engineer. Until 1932 he directed the construction of Rowanduz Road, a strategic route requiring many engineering feats, and it was during this project that the Callender-Hamilton truss bridge was born. Hamilton developed the idea further and it was patented in 1935.
The multi-truss multi-tier bridge system he developed, known as the Callender-Hamilton bridge, allowed faster than normal construction by unskilled technicians due to its prefabricated components. This bridging technique later proved to be extremely effective and was used in the development of military bridging prior to and during World War Two.
Callender-Hamilton truss bridges in New Zealand
More than 1,000 Callender-Hamilton bridges exist worldwide, across 50 countries. There are at least 17 bridges located in New Zealand. Most of the known remaining bridges are all on South Island State Highways.
This type of bridge was used by the Ministry of Works from the mid 1950s because the galvanised steel construction meant low maintenance costs and the standard design also allowed for simple construction and ease of transport. Callender-Hamilton bridges were perfect for Westland, which was still quite isolated at the time and has high rainfall.
Some New Zealand Callender-Hamilton bridges
Rangitikei River, Erewhon/Taihape-Napier Road, Hawke’s Bay
Pelorus River, State Highway 6, Marlborough
Mokihinui River, State Highway 67, West Coast
Wallace Point, State Highway 73, West Coast
Parkers Creek, State Highway 6, West Coast
Windbag Creek, State Highway 6, West Coast
Haast River, State Highway 6, West Coast
Greenstone Creek, State Highway 6, West Coast
Harris Creek, State Highway 6, West Coast
Cron Creek, State Highway 6, West Coast
Roaring Swine, State Highway 6, West Coast
Cache Creek, State Highway 6, West Coast
Haast River - Pleasant Flat, State Highway 6, West Coast
Gates of Haast, State Highway 6, West Coast
Tutoko River, State Highway 94, Fiordland
Donne River, State Highway 94, Fiordland
Gulliver River, State Highway 94, Fiordland.
Find out more
See list of bridges above.
“Bridge Replacement with Callender-Hamilton” New Zealand Engineering 10:4 (April 1955), 134.
William M Baker, Nicholas D Molcsan and Andrew H Buchanan, ‘Callender-Hamilton Truss Bridges: The New Zealand History,’ paper presented at the 4th Australasian Engineering Heritage Conference (2014).
A. M. Hamilton, ‘The Callender-Hamilton Bridging System,’ New Zealand Engineering 1:1 (April 1946), 30–31.