Civil Engineering heritage: Scotland - Lowlands and Borders
Date 2007
Event ID 578513
Category Descriptive Accounts
Type Publication Account
Permalink http://canmore.org.uk/event/578513
This iron suspension footbridge over the Tweed was erected in 1825–26 for use by pedestrians and horses. The work was undertaken by public subscription and the contractors were Redpath & Brown, Edinburgh. John S. Brown was the partner involved and he probably designed the ironwork. The masonry work was carried out by J. and T. Smith of Darnick for £600. Masonry towers on each bank, rising 38 ft above low-water level, support four suspension chains (two on each side) over a span of 296 ft. Their sag–span ratio is 1 :17.5 which was bold for its time. The tower saddles were rigidly fixed so that any temperature effects on the chains were accommodated by a small rise or fall of the deck. The chains consist of 10 f x 134 in. diameter eye-bar links connected by 7 in. long conventional links.
The 4 ft wide timber deck with its associated handcrafted ironwork was of light construction and for 167 years exhibited quite lively oscillations in strong winds. Concern for public safety by Borders Regional Council eventually led to the bridge being ingeniously strengthened in 1991-92, but with significant loss of its original ironwork and character. This involved replacing the original railings with substantial steel trusses, new hangers, saddles and anchorages. It also involved the provision of an additional steel-bar main chain on each side of the bridge to the same curvature, which involved widening the spacing of the original lines of chains forming each pair.
The engineers for this work were Travers Morgan. Examples of the original hand-crafted ironwork, including
hangers and fixings, railings, saddle and a ship’s rudder (which was loaded with stones as an anchorage) are now preserved and interpreted in the ICE Museum at Heriot-Watt University, Edinburgh.
R Paxton and J Shipway 2007
Reproduced from 'Civil Engineering heritage: Scotland - Lowlands and Borders' with kind permission from Thomas Telford Publishers.
