Great Western Main Line

Great Western Main Line
Maidenhead Railway Bridge carrying the line over the River Thames.
Overview
Status	Operational
Owner	Network Rail
Locale	Greater London South East England South West England
Termini	London Paddington Bristol Temple Meads
Stations	25
Service
Type	Commuter rail, Higher-speed rail[1]
System	National Rail
Operator(s)	Great Western Railway Elizabeth line Heathrow Express CrossCountry
Depot(s)	North Pole Reading St Philip's Marsh depot
Rolling stock	Class 158 Class 159 Class 165 Class 166 Class 220 Class 221 Class 345 Class 387 Class 800 Class 802
History
Opened	30 June 1841 (complete line)
Technical
Line length	118 miles 19 chains (190.28 km)
Number of tracks	Four (London to Didcot), two (Didcot to Bristol)
Track gauge	4 ft 8+1⁄2 in (1,435 mm)
Old gauge	7 ft 1⁄4 in (2,140 mm)
Electrification	25 kV 50 hz AC OLE (London to Chippenham)
Operating speed	125 mph (200 km/h)
Signalling	AWS, TPWS, ATP
Route map

v t e Great Western Main Line
Legend
miles Circle and Hammersmith & City lines via Liverpool Street Elizabeth line to Abbey Wood and Stratford 0⅓ London Paddington Paddington Goods Royal Oak ( ) Mileage Yard Goods & Coal Subway Junction Westbourne Park ( ) Portobello Junction Notting Hill Sidings Circle and Hammersmith & City lines to Hammersmith Kensal Green Gasworks siding Westway (A40) West London Line North Pole depot West London Junction Old Oak Common TMD Old Oak Common Goods Old Oak West Junction Acton–Northolt line Willesden & Acton Brick Co. siding Central line via Liverpool Street North London line Central line Western Avenue (A40) 4¼ Acton Main Line Central line District and Piccadilly lines 5¾ Ealing Broadway 6½ West Ealing Greenford branch line Plasser works 7¼ Hanwell Wharncliffe Viaduct over River Brent Brentford branch line 9⅓ Southall Grand Union Canal 11⅓ Hayes & Harlington Airport Junction to Heathrow Airport stations 14⅓ West Drayton River Colne Greater London boundary Uxbridge (Vine Street) branch line Staines and West Drayton Railway to Colnbrook Cargo Centre M25 motorway 14¾ Iver Western Rail Approach to Heathrow to Heathrow Terminals 2 & 3 and Terminal 5 (proposed) 16¼ Langley 18½ Slough Slough–Windsor & Eton line 21⅓ Burnham 22½ Taplow Jubilee River Maidenhead Railway Bridge over River Thames 24¼ Maidenhead Marlow branch line 31⅓ Twyford Henley branch line River Loddon Sonning Cutting 1 mile (1.6 km) long 60 feet (18 m) deep River Kennet Waterloo–Reading line North Downs Line Reading East Junction 36⅓ Reading Reading–Basingstoke line and Reading–Taunton line 38¾ Tilehurst Purley Cutting 41½ Pangbourne Gatehampton Railway Bridge over River Thames 44¾ Goring & Streatley Moulsford Railway Bridge over River Thames Moulsford 48½ Cholsey Cholsey & Wallingford Railway (bank holidays and weekends only) Didcot, Newbury and Southampton Railway 53⅓ Didcot Parkway Didcot Railway Centre Cherwell Valley line to Oxford, Birmingham and the Cotswold Line Didcot power stations Milton Park estate Steventon Wantage Tramway Wantage Road Challow Uffington Faringdon branch Shrivenham Stratton Park Halt Highworth branch line 77¼ Swindon Golden Valley line to Cheltenham Spa and Birmingham Midland & South Western Junction Railway M4 motorway Wootton Bassett Junction South Wales Main Line Dauntsey Malmesbury branch line Christian Malford Halt Calne branch line 94⅓ Chippenham Thingley Junction Wessex Main Line to Melksham, Bradford-on-Avon and Salisbury Corsham Box Tunnel 2939 yd 2687 m Box (Mill Lane) Halt Box Bathford Halt Bathford Bridge over River Avon Wessex Main Line to Weymouth, Southampton and Brighton Bathampton Junction Bathampton Hampton Row Halt 107⅓ Bath Spa 108⅓ Oldfield Park Somerset & Dorset Joint Railway Twerton-on-Avon Twerton Tunnel Saltford Tunnel Saltford 113¾ Keynsham St Anne's Park No 3 Tunnel 1017 yd 930 m St Anne's Park No 2 Tunnel 154 yd 141 m St Anne's Park River Avon North Somerset Junction Bristol & North Somerset Railway St Philip's Marsh TMD Cross Country Route to Gloucester & Birmingham New Street to Mangotsfield to Ashton Gate Platform 116½ Bristol Temple Meads Bristol West Junction Temple Meads Goods Bristol–Exeter line

The Great Western Main Line (GWML) is a main line railway in England that runs westwards from London Paddington to Bristol Temple Meads. It connects to other main lines such as those from Reading to Penzance and Swindon to Swansea. The GWML is presently a part of the national rail system managed by Network Rail while the majority of passenger services upon it are provided by the current Great Western Railway franchise.

The GWML was built by the original Great Western Railway company between 1838 and 1841, as a dual track line in the 7 ft (2,134 mm) broad gauge. The broad gauge remained in use until 1892, after which standard gauge track has been exclusively used. Between 1877 and 1932, many sections of the GWML were widened to four tracks. During 1908, Automatic Train Control (ATC) was introduced as a safety measure. In 1948, the Great Western Railway, and thus the GWML, was merged into the Western Region of British Railways.

During the 1970s, the GWML was upgraded to support higher line speeds, as a result of which many sections permitted 125 mph (201 km/h) operations, enabling the newly introduced InterCity 125 high speed train (HST) to make faster journeys. British Rail proposed widespread electrification of the line in the late 1970s, although this was not speedily implemented. During the mid-1990s, a stretch of the GWML between London Paddington and Hayes & Harlington was electrified using 25 kV AC overhead lines for the Heathrow Express. Further, although not total, electrification was carried out during the 2010s; this permitted the replacement of diesel-powered trains such as the InterCity 125 and Class 180 with electric and bi-mode train sets such as the Hitachi Super Express high speed trains, specifically the Class 800 and Class 802. Due to budget overruns, the British government deferred electrification of the section through Bath Spa from Royal Wootton Bassett to Bristol in 2016.

Communities served by the GWML include West London (including Acton, Ealing, Hanwell, Southall, Hayes, Harlington and West Drayton); Iver; Langley; Slough; Burnham; Taplow; Maidenhead; Twyford; Reading; Tilehurst; Pangbourne; Goring-on-Thames; Streatley; Cholsey; Didcot; Swindon; Chippenham; Bath; Keynsham; and Bristol. The route includes dozens of listed buildings and structures, including tunnel portals, bridges and viaducts, stations, and associated hotels. Presently, the GWML is electrified between London Paddington and Royal Wootton Bassett. In the long term, Network Rail plans to install European Rail Traffic Management System (ERTMS) in-cab signalling across the entire line.