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SD50NE 24/2/10079 23-MAR-01

WALLGATE Wigan (South,off) Adam Viaduct

II

Under bridge, set within longer railway embankment. 1946 by the London, Midland and Scottish Railway; chief engineer W K Wallace; contractors Leonard Fairclough Limited. Reinforced pre-stressed pre-cast deck units on in-situ reinforced concrete piers set on old foundations. Pre-cast concrete parapet units, and original concrete handrails and standards on east side. Four spans, the end two 29'9" wide, those in the centre 29'4" and 28'6" wide, with a deck formed of `I'-beams 32" deep. The small space between the top flanges of the `I'-beams which supported the tracks is grouted, and high-tensile tie roads, tightened by the nuts at each end, tie the beams together so that they act together under live load.

The Adam Viaduct is internationally understood to be the earliest pre-stressed railway bridge in England. Only examples in Switzerland are considered to be earlier. The LMS had established a pioneering research institution in 1932 at Derby, where it built extensive testing laboratories in 1935. It developed the use of pre-cast concrete in the 1930s because it was strong, long-lasting and cheap, and because pre-cast units could be installed on the line quickly. But the large depth of the beams required for spans of up to forty feet made the technique of limited use for under bridges. Pre-stressed beams were used for emergency repairs in the war, but this is their first full-scale, designed use.

Sources Arthur Dean, Prestressed Concrete applied to the Construction of Railway Bridges and Other Works, Proceedings of the Institution of Civil Engineers Railway Division, vol.44, 1951, p.14 Concrete and Constructional Engineering, vol.42, 1947, pp.305-8 F G Thomas, Prestressed Concrete, n.d.