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Civil Engineering heritage: Scotland - Lowlands and Borders
Date 2007
Event ID 606509
Category Descriptive Accounts
Type Publication Account
Permalink http://canmore.org.uk/event/606509
The creation of Loch Faskally by the construction of Pitlochry dam raised the water level of the Tummel by about 40 ft, submerging the two-span masonry arch Clunie Bridge. It was decided to replace it by a pedestrian bridge nearby.
The new bridge, erected in 1950, the only one of its kind in Scotland, is unusual in being built of aluminium alloy
trusses. It is 31012 ft long with a centre span of 17212 ft and two side spans of 69 ft and is designed for a live load of 84 lb sq. ft over a deck width of 612 ft. Although arched in elevation it functions as a cantilever beam bridge constructed of twin ‘N’ truss girders braced at the deck and arch soffits.
The material for the main members of the bridge is AW10B alloy. Little information on aluminium alloy riveting practice was available at the time of erection and this aspect required careful investigation. As aluminium has a very low modulus of elasticity compared to steel it might be thought that the slender design would be vulnerable to deflection effects or vibration, but this has not proved to be the case.
The consulting engineers were Sir Alexander Gibb & Partners and the contractors P. & W. McLennan Ltd, Glasgow. The aluminium alloys were supplied by James Booth & Co. Ltd. The concrete piers were constructed by Wm. Tawse, Aberdeen.
R Paxton and J Shipway
Reproduced from 'Civil Engineering heritage: Scotland - Lowlands and Borders' with kind permission of Thomas Telford Publishers.
