Callender-Hamilton bridge

The Callender-Hamilton bridge is a modular portable pre-fabricated truss bridge. It is primarily designed for use as permanent civil bridging as well as for emergency bridge replacement and for construction by military engineering units. Assembling a Callender-Hamilton bridge takes much longer than the more familiar Bailey bridge as it is made up of individual lengths of galvanised steel bolted together with galvanised high-strength steel bolts, all of which require torque settings. It is stronger and simpler in design concept than the Bailey bridge.

The Callender-Hamilton bridge system was designed by the New Zealand civil engineer, A. M. Hamilton, and patented by him in 1935. The system is currently fabricated by Painter Brothers, Hereford, operating within the Balfour Beatty Power Networks Division formerly British Insulated Callender's Cables.

Hamilton's bridge concept was inspired by his work between 1928 and 1932 as principal engineer on the 'Hamilton Road' through Iraqi Kurdistan. He described the building of this road in his book, Road Through Kurdistan: Travels in Northern Iraq, 1937. Hamilton became aware of the need for strong, adaptable bridges made from simple components that could easily be transported and erected in remote locations or on difficult terrain. Hamilton was awarded £4,000 in 1936 by the War Office for the use of his early bridges and the Royal Commission on Awards to Inventors awarded him £10,000 in 1954 for the partial breach of his patent by the design of the Bailey bridge.

The Callender-Hamilton bridge system is a prefabricated Panel/Floor Beam/Deck system designed to span bridging lengths ranging from 30 to 150 metres with road widths of one to three or more lanes. The design uses Warren trusses and is centred on a series of gusset plates that allow the direct attachment of the longitudinal, diagonal, vertical, and cross framing members. Centralised connection points increase the speed of construction and allow identical panels to be fabricated from identical members and then installed on site. An important feature is that all connections are bolted, so removing the need for onsite welding.

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