Glasgow, Clyde Street, Union Railway Bridge

Union Bridge orignally built 1870 and modified in 1898 to cater for expansion.

This project was undertaken to input site information listed in 'Civil engineering heritage: Scotland - Lowlands and Borders' by R Paxton and J Shipway, 2007.

The twin-track seven-span iron-girder viaduct, opened in 1870 on the City of Glasgow Union Railway, the first city railway crossing of the Clyde connecting the Glasgow & Paisley Joint and North British lines, was kept operational whilst the present bridge was ingeniously built around it. The engineers for the 1870 bridge, with its typical double-lattice girders 8 ft deep, were John Fowler and J. F. Blair and the contractors, Brassey & Co.

An innovative construction feature was the use of 8 ft diameter cast-iron cylindrical foundations achieved by means of Milroy’s excavator and cylinder sinking method to reach a firm base up to 100 ft below. The cylinders were sunk by applying curved weights on top to force down those below. The soft earth from within was removed by a 5 ft diameter grab type excavator. Keeping the cylinders full of water enabled about 34 cubic yards of soft earth to be brought to the surface at each lift. The cylinders were then filled with concrete and brickwork and are believed to still exist. The 1898 bridge was built around it (NS56SE 144.01).

Although St Enoch’s Station was closed in 1966 and subsequently demolished, the viaduct is still in use, mainly for freight traffic.

R Paxton and J Shipway 2007

Reproduced from 'Civil Engineering heritage: Scotland - Lowlands and Borders' with kind permission of Thomas Telford Publishers.