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Civil Engineering heritage: Scotland - Highlands and Islands
Date 2007
Event ID 962661
Category Descriptive Accounts
Type Publication Account
Permalink http://canmore.org.uk/event/962661
Bonar Bridge
The first bridge built on this site (see also NH69SW 62.00 and NH69SW 62.01) by Simpson and Cargill, contractors for both masonry and ironwork, incorporated Telford’s innovative light prefabricated cast-iron lattice spandrel arch of 150 ft span designed in 1810 and pre-erected by ironfounder William Hazledine at Ruabon in June 1812.
Originally, one arch was thought to provide sufficient waterway if founded on rock but, because of foundation difficulties, this was not possible and, after considering twin rim arches additional masonry spans of 50 ft and 60 ft were adopted to reduce the pressure on the iron bridge pier in times of flood. The bridge was erected in 1812 at a cost of £13 971 (ironwork £3947).
This project, involving the longest such prefabricated span in 1812, constituted an epoch-making iron bridge development. By 1830 at least ten arches of this genre had been erected in Britain as far south as Tewkesbury, of which the second, at Craigellachie (NJ24NE 15 ), is now the earliest survivor. Many later bridges until the turn of the century, for example Carron (1862-3, NJ24SW 14), were influenced in their appearance by the lattice spandrel elevation of this bridge type.
R Paxton and J Shipway, 2007.
Reproduced from 'Civil Engineering heritage: Scotland - Highlands and Islands' with kind permission from Thomas Telford Publishers.
