South Wales Main Line

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South Wales Main Line
The entrance to the Chipping Sodbury Tunnel with the newly electrified overhead line equipment
Overview
Status	Operational
Owner	Network Rail
Locale	South Wales South West England
Stations	18
Service
Type	Heavy rail
System	National Rail
Operator(s)	Transport for Wales CrossCountry Great Western Railway
History
Opened	1850; 174 years ago (1850) (Chepstow-Swansea) 1903; 121 years ago (1903) (Swindon-Patchway)
Technical
Line length	84 miles 30 chains (135.79 km)
Number of tracks	Mainly double track, though quadruple track from Severn Tunnel Junction via Newport to Cardiff Central.
Character	Main line
Track gauge	4 ft 8+1⁄2 in (1,435 mm) standard gauge
Electrification	25 kV 50 Hz AC OHLE (Wootton Bassett to Cardiff Central)
Operating speed	Up to 125 mph (201 km/h) in England Up to 100 mph (161 km/h) in Wales
Route map (Click to expand)

v t e South Wales Main Line
Legend
Miles 0⅓ London Paddington Great Western Main Line 77¼ Swindon Golden Valley line Wootton Bassett Road Wootton Bassett Junction Great Western Main Line to Bristol Temple Meads Brinkworth Little Somerford Malmesbury branch Hullavington Alderton Tunnel Badminton Chipping Sodbury Tunnel 2 mi 924 yd / 4.06 km Chipping Sodbury Westerleigh Junction Cross Country Route Bristol and Gloucester Railway to Westerleigh goods depot Coalpit Heath Wessex Main Line and Great Western Main Line Winterbourne 117¾ Bristol Temple Meads Bristol–Exeter line 116¾ Lawrence Hill 116¼ Stapleton Road Severn Beach line 111¾ Bristol Parkway 113⅓ Filton Abbey Wood Stoke Gifford depot Henbury Loop Line 113⅓ Patchway Patchway Tunnel 1 mi 2 km 116½ Pilning England Wales Severn Tunnel 4 mi 624 yd 7.01 km Gloucester–Newport line MoD Caerwent Caldicot 123½ Severn Tunnel Junction Undy Halt Magor Flying junction Bishton Crossing Llanwern steelworks Llanwern Goods line to Uskmouth East Usk Maindee Junction Welsh Marches line Bridge over River Usk Monmouthshire Railway Newport (Mill Street) 133½ Newport Hillfield Tunnel 770 yd 704 m Gaer Junction Alexandra Dock Ebbw Valley Railway Ebbw Junction Ebbw River Marshfield Wentlooge Freightliner terminal River Rhymney Roath Long Dyke Junction Valleys & Cardiff Local Routes Cardiff Queen Street Cardiff Bay 145¼ Cardiff Central River Taff Cardiff Canton TMD Vale of Glamorgan Line Ninian Park Leckwith Junction Valleys & Cardiff Local Routes to Pontypridd Ely Main Line River Ely St Fagans River Ely Peterston River Ely River Ely Pontyclun River Ely Llantrisant & Taff Vale Junction Railway 156¼ Llanharan Llynvi and Ogmore Railway to Brynmenyn 161½ Pencoed Vale of Glamorgan Line 165¼ Bridgend Maesteg Line River Ogmore 171½ Pyle Water Street Junction Goods line to Tondu Margam Knuckle Yard Port Talbot Steelworks (Port of Port Talbot) 177⅖ Port Talbot Parkway Margam Halt River Afan 179¾ Baglan Baglan Bay 181½ Briton Ferry Court Sart Junction Swansea District line 183⅓ Neath Neath Canal River Neath Vale of Neath Railway Tennant Canal 187⅓ Skewen Swansea District line to Llanelli 188¾ Llansamlet Swansea Vale Railway Llansamlet cutting Landore viaduct over River Tawe Landore High Level Swansea Loop East Junction Landore TMD 191⅓ Swansea Swansea Loop West Junction Landore Junction West Wales line

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 beyond Swindon, first calling at Bristol Parkway, after which the line continues through the Severn Tunnel into South Wales.

Much of the South Wales Main Line was built between the 1830s and 1886; originally trains to and from destinations in England ran via Chepstow, Gloucester and Stroud, joining the Great Western Main Line at Swindon. A more direct route was challenging yet desirable, leading to the construction of the line's most prominent civil engineering features, the Severn Tunnel. Completed in 1886, it permitted a significant reduction in journey times between various destinations, especially after the construction of the Badminton Line in 1903. During the British Rail era, the line was incorporated into the Western Region and steam locomotives were replaced by diesel locomotives, such as the Intercity 125 high speed trainsets. During the 2010s, the line between Swindon and Cardiff Central was electrified using the 25 kV AC overhead system as part of the wider electrification of the Great Western Main Line; this has permitted the operation of electric traction between Cardiff and London for the first time to commence in 2020.

Presently, Great Western Railway operates Class 800 trains between London and South Wales, and "Castle class" High Speed Trains on 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. Transport for Wales operates services between South Wales, and North Wales and the Midlands on the line. Operations are mostly managed from the Wales Rail Operating Centre in Cardiff; digital signalling is to be rolled out.