This entry relates to the first iron viaduct over the River Gaunless.
This very early lenticular truss bridge was probably the first iron bridge used on a public railway (as distinct from tramway bridges used on ironworks).
The bridge remained intact until 1901 when it was dismantled. It was later re-erected in the Queen Street Museum, York for its opening in 1928. It was re-erected at the National Railway Museum in 1975.
The five pairs of splayed cast iron columns and cross beams are connected by girders of 12ft 6in span: these are of curved wrought iron bars with cast iron vertical posts supporting the longitudinal deck members and track. 
Sources of Information
- The Engineer 1875/09/24
-  Science Museum Group: 'Bridge used to span the River Gaunless at West Auckland'
- 'The Britannia and other Tubular Bridges' by John Rapley, Tempus Publishing 2003