Civil Engineering heritage: Scotland - Lowlands and Borders
Date 2007
Event ID 610159
Category Descriptive Accounts
Type Publication Account
Permalink http://canmore.org.uk/event/610159
The Tay is a shallow estuary, nearly two miles wide at Dundee, with many sandbanks and a depth of water rarely exceeding 50 ft. The present railway bridge is the second at the same site, the first having collapsed barely 18 months after its opening.
The first Tay Bridge was designed in the 1870s for the North British Railway by its Engineer Thomas Bouch and carried a single line of railway on 89 spans. Thirteen of these spans were navigation spans higher and longer than the others. The spans were originally to have been carried on tall piers of brickwork founded on solid rock but, owing to faulty site investigation and difficulties with the foundations, the majority of the piers had to be lightened and were made of poorly constructed ironwork which was insufficiently anchored at its base. In a gale on 28 December 1879 all the navigation spans fell while a train was crossing and 75 lives were lost. Although the bridge had stood for only 18 months it had more than demonstrated its usefulness, and the North British Railway determined to rebuild it. The present bridge 10 711 ft in length and double track was engineered by W. H. Barlow from 1881, assisted by his son and partner Crawford Barlow. Although structural steel was coming into use, no substantial bridges in Britain had been completed using it, and it was decided to use 21 078 tons of wrought-iron girders capable of bearing 22 tons sq. in. in tension, plus 3588 tons of steel in the flooring. The contractor was William Arrol, who designed innovative temporary works, including pontoon jack-upplatforms (see illustration). He proved more than equal to this mammoth task.
Construction took place from 1882–87, on a parallel line 60 ft upstream from the old bridge. The spans were kept the same as Bouch’s bridge, which allowed the original iron girders (which were sound, unlike the ironwork of the piers) to be reused as facing girders except on the navigation spans which were entirely renewed. The new piers were substantial and well anchored.
Network Rail’s recent sensitive refurbishment of the bridge won the Saltire Civil Engineering Award for 2003.
Paxton and Shipway 2007
Reproduced from 'Civil Engineering heritage: Scotland - Lowlands and Borders' with kind permission from Thomas Telford Publishers.
