The Alderton Tunnel sits on the

South Wales Main Line The South Wales Main Line ( cy, Prif Linell De Cymru), originally known as the London, Bristol and South Wales Direct Railway or simply as the Bristol and South Wales Direct Railway, is a branch of the Great Western Main Line in Great Britain. ...

in England, on a stretch of line between Swindon and Bristol Parkway. The tunnel, which is 506 yards () long, was opened on 1 January 1903 along with the line between Wootton Bassett Junction and , that being the first section of the South Wales & Bristol Direct Line of the Great Western Railway. Building of the tunnel commenced at least two years before 1903, as the rise in railway workers boarding in Alderton village can be seen in the 1901 Census. As part of the modernisation of the Great Western main line, the route through the tunnel closed from 19 August to 15 September 2017 to allow overhead electrification equipment to be fitted.

References

South Wales Main Line Railway tunnels in England Rail transport in Wiltshire Great Western Railway Tunnels completed in 1903 Tunnels in Wiltshire {{England-rail-transport-stub