Oaks Viaduct was Britain's largest railway bridge that spanned the Dearne Valley, in South Yorkshire. The viaduct crossed Rotherham Road at Lundwood, and spanned across the Dearne Valley including the Dearne and Dove Canal, to the other side, connecting with Barnsley Colliery, and joined the existing Barnsley - Sheffield line.
It served as an alternative line for trains between Leeds and Sheffield on the Midland Railway's main line forming the last link in the Cudworth to Wincobank "Chapeltown loop". This allowed trains to avoid congestion in the Wath-upon-Dearne and Swinton areas, albeit by the slower and more hilly line. The "Cudworth Flyer" local train from Barnsley, connecting with Midland line trains at Cudworth, also passed over the viaduct. It also served as a railway for the coal industry, allowing access to the many rail-connected collieries in the area, serving Wombwell Main, Darfield Main and Wath Main Colliery.
In 1965, the bridge was deemed unsafe, leading to the withdrawal of all train services and the eventual demolition of the bridge.
Coordinates: 53°33′22″N 1°26′38″W / 53.556°N 1.444°W / 53.556; -1.444