South Wales Main Line

South Wales Main Line
The entrance to the Severn Tunnel on the English side
Overview
Type	Heavy rail
System	National Rail
Status	Operational
Locale	South Wales South West England
Stations	18
Operation
Opened	1850 (Chepstow-Swansea) 1903 (Swindon-Patchway)
Owner	Network Rail
Operator(s)	Arriva Trains Wales CrossCountry Great Western Railway
Character	Main line
Technical
Line length	84.38 miles (135.80 km)
Number of tracks	Mainly double track, though quadruple track from Severn Tunnel Junction via Newport to Cardiff Central.
Track gauge	4 ft 8 1⁄2 in (1,435 mm) standard gauge
Electrification	25kV 50Hz AC OHLE (Wootton Bassett to Cardiff Central by 2017 & Swansea by 2018)

The South Wales Main Line (Welsh: 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. It diverges from the core London-Bristol line at Royal Wootton Bassett near Swindon, first calling at Bristol Parkway, after which the line continues through the Severn Tunnel into South Wales.

Great Western Railway operates High Speed Trains between London and South Wales and services between Cardiff and South West England. CrossCountry provides services from Cardiff to Nottingham via Severn Tunnel Junction and thence the Gloucester to Newport Line via Gloucester and Birmingham. Arriva Trains Wales operates services between South Wales, and North Wales and the Midlands on the line.

It is planned to electrify the line using the AC overhead system, with completion by 2018.

The original route of the Great Western Railway (GWR) between London and South Wales, after the opening of Brunel's Chepstow Railway Bridge in 1852, left the Bristol-bound Great Western Main Line at Swindon, proceeding via Stroud, Gloucester and Chepstow before rejoining the line as we know it today at Severn Tunnel Junction. This gave rise to the nickname 'Great Way Round'.