Civil Engineering heritage: Scotland - Lowlands and Borders
Date 2007
Event ID 578139
Category Descriptive Accounts
Type Publication Account
Permalink http://canmore.org.uk/event/578139
Tongland Bridge now carries the A711 about 60 ft over the Dee near Kirkcudbright. It was projected in 1803 and built from 1804–08 to link the port of Kirkcudbright with Ayrshire, Dumfries and Portpatrick, and its cost of £7710 was financed mainly by the Stewartry’s Commissioners of Supply, with £1100 from public subscription. It comprises a single segmental arch of 112 ft span with a rise of 32 ft, flanked by three narrow pointed Gothic
arches on each side, and is built mainly in rough-faced grey sandstone from Arran on which stone duty was
charged. The interior part of the arch is formed of a red sandstone from Annan.
The bridge was planned and designed by Telford, with a significant input to its external appearance from artist/
architect, Alexander Nasmyth. It was contracted for by country masons Sam and Alex McKean, S. Hyslop and A.
McGuffery in late 1803 and the foundation stone laid in March 1804. But the timber centring to carry a 133 ft arc
of arch-stones 312 ft deep for one of Britain’s largest spans proved beyond the masons’ skills and was demolished by flood water in August 1804.
Telford was called in to remedy matters. The contractors were relieved of their obligation to build the bridge for
what he considered the ‘quite impossible’ price of less than £3000, and Adam Blane was brought in as resident engineer. Under Blane’s direction the arch-ring was completed by day labour, using the centring shown, on 29 August 1805 and the whole bridge by 21 May 1808. The bridge was passable from November 1806.
The bridge is of particular interest as Telford’s earliest large span masonry arch and for his use of hollow spandrels to obviate outward pressure from internal fill, to reduce the weight on the foundations, and to facilitate inspection. Four slabbed-over cavities, wide enough to accommodate a man, run longitudinally. Although Telford did not invent this concept (see 6-16, Perth Bridge), he developed and promoted it for large spans using Tongland as an example in his landmark ‘Bridge’ treatise in the Edinburgh Encyclopaedia from 1812. More locally he would have been aware of their use at Gilnockie Bridge (NY 3860 7815) with its handsome 70 ft main span and rise of about 25 ft built in ca.1800 at Hollows adjoining the Carlisle road four miles south of Langholm.
As an admirer of the Gothic style, Telford would have been pleased to include in his plan the turreted and
embattled elevation in rustic-style masonry of Nasmyth’s design. Between the main span and the pointed arch
side spans, semi-circular cutwaters extend as turrets to parapet height, forming pedestrian refuges at road level. The parapet is corbelled out but, as can be seen from the comparison of the photograph and Nasmyth’s drawing, Telford did not adopt Nasmyth’s castellation over the side spans or his eight octagonal towers above stringer level.
The bridge was strengthened in the mid-20th century with the provision of a reinforced concrete slab across the tops of the hollow spandrel walls.
The nextmajor bridge to be erected over the Dee, 112
miles
downstream at Kirkcudbright, was a wrought iron bow truss bridge, with five spans of 71 ft and an opening span of 93 ft, erected in 1868. The engineer was H. J. Wylie and the contractors, Hopkins, Gilkes & Co., Middlesbrough. The bridge plates from its curved approaches can be seen at the entrance to Kirkcudbright Museum.
This bridge was replaced in 1926, retaining the original lamp standards, by the present five-span reinforced
concrete bowstring bridge of similar appearance engineered by Blyth & Blyth and L. G. Mouchel & Partners. It is a slender and notable example of its type from the era when it was fashionable to reproduce confidently traditional bridge types in the new material, even a suspension bridge at Montrose!
R Paxton and J Shipway 2007
Reproduced from 'Civil Engineering heritage: Scotland - Lowlands and Borders' with kind permission from Thomas Telford Publishers.
