Great Western Main Line

Great Western Main Line

Maidenhead Railway Bridge carrying the line over the River Thames.
Type Commuter rail, Higher-speed rail[1]
System National Rail
Status Operational
Locale Greater London
South East England
South West England
Termini London Paddington
Bristol Temple Meads
Stations 25
Opened 30 June 1841 (complete line)
Owner Network Rail
Operator(s) Great Western Railway
Heathrow Connect
Heathrow Express
Chiltern Railways
South West Trains
Depot(s) Reading TMD
Old Oak Common TMD
Rolling stock Class 43 "HST"
Class 57
Class 150 "Sprinter"
Class 153 "Super Sprinter"
Class 158 "Express Sprinter"
Class 159 "South Western Turbo"
Class 165 "Networker Turbo"
Class 166 "Networker Turbo Express"
Class 180 "Adelante"
Class 220 "Voyager"
Class 221 "Super Voyager"
Class 332
Class 360 "Desiro"
Class 387 "Electrostar"
Line length 119 mi (192 km)
Number of tracks Four (London to Didcot)
Two (Didcot to Bristol)
Track gauge 1,435 mm (4 ft 8 12 in)
Old gauge 7 ft 14 in (2,140 mm)
Electrification Mk3b, Series 1 and UK Master Series 25kV 50hz AC OLE
(Paddington to Airport Junction) (West Drayton to Temple Meads by 2016)
Operating speed 125 mph (201 km/h) maximum
Route map

(interactive map)

Great Western Main Line

miles Circle and Hammersmith & City lines
Crossrail Elizabeth line
(under construction, opening 2018)

0 London Paddington London Underground
Royal Oak
Subway Junction
Westbourne Park

Circle and Hammersmith & City lines
West London Line
Old Oak
Common TMD
North Pole
Old Oak West Junction
Acton–Northolt Line

Central line
to Central London

North London Line
(London Overground) London Overground

Central line
to North Acton
Western Avenue
Acton Main Line

Central line
to North Acton

District line
5⅝ Ealing Broadway London Underground
West Ealing

Greenford Branch Line
Plasser Works

Wharncliffe Viaduct
over River Brent
Brentford Branch Line (freight only)
9 Southall
Grand Union Canal
10⅞ Hayes & Harlington
Airport Junction
to Heathrow Airport
13⅛ West Drayton
River Colne
Limit of Greater London and TfL area

13⅜ Uxbridge (Vine Street) Branch Line
Staines and West Drayton Railway
to Colnbrook Cargo Centre (freight only)
14¾ Iver

Western Rail Approach to Heathrow
to Heathrow Central and Terminal 5 (proposed)
16⅛ Langley
18⅜ Slough
Slough to Windsor & Eton Line
20⅞ Burnham
22⅜ Taplow
Jubilee River
Maidenhead Railway Bridge
over River Thames
24⅛ Maidenhead
Marlow Branch Line
31 Twyford
Henley Branch Line
River Loddon
Sonning Cutting
1 mile (1.6 km) long
60 feet (18 m) deep
River Kennet
Waterloo to Reading Line to London
North Downs Line to Gatwick Airport
35⅛ Reading East Junction
36 Reading
Reading to Basingstoke Line
and Reading to Taunton line
38⅝ Tilehurst
Purley Cutting
41½ Pangbourne
Gatehampton Railway Bridge
over River Thames
44¾ Goring & Streatley
Moulsford Railway Bridge
over River Thames
48⅜ Cholsey
Cholsey and Wallingford Railway
(bank holidays and weekends)

Didcot, Newbury and
Southampton Railway
53⅛ Didcot Parkway
Cherwell Valley Line
to Oxford, Birmingham and the Cotswold Line
56⅜ Steventon
Stocks Lane, Steventon
The Causeway, Steventon
Wantage Tramway
60¼ Wantage Road
A417 road
64 Challow
66⅜ Uffington
Faringdon branch
Stratton Park Halt
Highworth Branch
(freight only)
77¼ Swindon
Golden Valley Line
to Cheltenham Spa and Birmingham
Wootton Bassett
82⅞ South Wales Main Line
87⅝ Dauntsey
Malmesbury branch
Christian Malford Halt
Calne branch
93⅞ Chippenham
96⅛ Thingley Junction

Wessex Main Line
to Melksham, Bradford-on-Avon and Salisbury
Box Tunnel
2939 yd
2687 m
Box (Mill Lane) Halt(1930–1965)
Bathford Halt(1929–1965)
Bathford Bridge
over River Avon
Wessex Main Line
to Weymouth, Southampton and Brighton
104⅝ Bathampton Junction
Hampton Row Halt
106⅞ Bath Spa
107⅞ Oldfield Park
Somerset and Dorset Joint Railway
108⅞ Twerton-on-Avon
Twerton Tunnel
Saltford Tunnel
113¾ Keynsham
Keynsham Tunnel
St Anne's Park
117½ North Somerset Junction
Bristol and North Somerset Railway
118 St Philip's Marsh TMD
Cross Country Route
to Gloucester, Birmingham and the Severn Tunnel
118⅜ Bristol Temple Meads
118⅝ Bristol West Junction
Bristol to Exeter Line

The Great Western Main Line is a main line railway in Great Britain, that runs westwards from London's Paddington station to the west of England and South Wales. The core Great Western Main Line runs from London Paddington to Temple Meads railway station in Bristol. A major branch of the Great Western, the South Wales Main Line, diverges from the core line west of Swindon and terminates in Swansea. The term "Great Western" is also used by Network Rail and other rail transport organisations in the UK rail industry to denote a wider group of associated routes.

The core London–Bristol Temple Meads line is the original route of the pre-1948 Great Western Railway which was subsequently taken over by the Western Region of British Railways and is now part of the Network Rail system.

The line is mostly non-electrified. It was partly electrified from Paddington to Heathrow Airport in the late 1990s. In 2011, Network Rail commenced a scheme to electrify the entire main Great Western route to Bristol by 2016.[2] This programme has however slipped at least two years behind schedule.


The line was built by the Great Western Railway and engineered by Isambard Kingdom Brunel as a dual track line using a wider 7 ft (2,134 mm) broad gauge and was opened in stages between 1838 and 1840. The alignment was so level and straight it was nicknamed ‘Brunel’s Billiard Table’. It was supplemented with a third rail for dual gauge operation allowing standard gauge 4 ft 8 12 in (1,435 mm) trains to also operate on the route in stages between 1854 and 1875. Dual gauge was introduced as follows: London to Reading (1 October 1861), Reading to Didcot (22 December 1856), Didcot to Swindon (February 1872), Swindon to Thingley Junction, Chippenham (June 1874), Thingley Junction to Bathampton (16 March 1875), Bathampton to Bristol (June 1874), Bristol station area (29 May 1854). The broad gauge remained in use until 1892. Evidence of the original broad gauge can still be seen at many places where bridges are a wider than usual, or where tracks are ten feet apart instead of the usual six.

The original dual tracks were widened to four track in various places between 1877 and 1899. Paddington to Southall (1 October 1877), Southall to West Drayton (25 November 1878), West Drayton to Slough (1 June 1879), Slough to east side of Maidenhead Bridge (8 September 1884), Maidenhead Bridge to Reading (4 June 1893), Reading station (1899), Reading to Pangbourne (30 July 1893), Pangbourne to Cholsey and Moulsford (?), Cholsey and Moulsford to Didcot (27 December 1892), Various short sections between Didcot and Swindon, and at Bristol.

Following the Slough rail accident in 1900 when five passengers were killed, improved vacuum braking systems were used on locomotives and passenger rolling stock and Automatic Train Control (ATC) was introduced in 1908.

Further widenings of the line took place between 1903 and 1910.[3]

At the outbreak of World War I in 1914, the Great Western Railway was taken into government control, as were most major railways in Britain and were reorganised after the war into the "big four" companies, of which the Great Western Railway was one. The railways returned to direct government control during World War II before being nationalised to form British Railways in 1948.

More widening infrastructure work took place between 1931 and 1932, and the extension to south wales was quadrupled 1941.[3]

The line speed was upgraded in the 1970s to support the introduction of the InterCity 125 (HST).[4]

In 1977 the Parliamentary Select Committee on Nationalised Industries recommended considering electrification of more of Britain's rail network, and by 1979 BR presented a range of options that included electrifying the GW Main Line from Paddington to Swansea by 2000.[5] Under the 1979–90 Conservative governments that succeeded the 1976–79 Labour government the proposal was not implemented.

In August 2008 it was announced that a number of speed limits on the relief lines between Reading and London have been raised so that 86% of the line can be used at 90 miles per hour (140 km/h),[6] however the time allowed between stations for trains running on the relief lines has been reduced in the December 2008 timetable to improve timekeeping.[7]


The route of the GWML includes dozens of listed buildings and structures, including tunnel portals, bridges and viaducts, stations, and associated hotels.[8] Part of the route passes through and contributes to the Georgian Architecture of the City of Bath World Heritage Site - the path through Sydney Gardens has been described as a "piece of deliberate railway theatre by Brunel without parallel".[9] Grade I listed structures on the line include London Paddington, Wharncliffe Viaduct, the 1839 Tudor gothic River Avon Bridge in Bristol, and Bristol Temple Meads Station.[10]


The communities served by the Great Western Main Line 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.

From London to Didcot, the line follows the Thames Valley, crossing the River Thames three times, including on the famous Maidenhead Railway Bridge. After Swindon, trains pass the Swindon Steam Railway Museum. From Wootton Bassett there are two different routes to Bristol, firstly via Box Tunnel and secondly via Bristol Parkway.

It is also possible to run via the Wessex Main Line, but this involves a reversal at Bradford Junction, so is only really suitable for multiple unit trains or via Reading to Bath via Newbury. Trains on the Great Western Main Line are sometimes diverted from Reading along the Reading to Taunton line, as far as Westbury, from where they can use the Wessex Main Line to reach either Chippenham, or Bath Spa. Beyond Bristol, some trains continue on the Bristol to Taunton Line to Weston-super-Mare or beyond.

The following routes are managed by Network Rail as part of the Great Western Main Line (Route 13):[11] Didcot to Oxford and Worcester via the Cherwell Valley Line and Cotswold Line, Swindon to Cheltenham Spa via the Golden Valley Line, Swindon to Cardiff Central and Swansea via the South Wales Main Line, Cross Country Routes south of Birmingham and also all connecting branch lines.


Main line and local services are provided by Great Western Railway (GWR). The stations served by trains between London Paddington and Bristol Temple Meads are: Slough, Reading, Didcot Parkway, Swindon, Chippenham, and Bath Spa. Not all trains between London and Bristol call at Slough, Didcot, Chippenham, and Bath Spa

Fast trains from Paddington to London Heathrow Airport are operated by Heathrow Airport Holdings as the Heathrow Express. Local services on this route are jointly operated by GWR and BAA under the Heathrow Connect name.

CrossCountry operate trains between Reading and Oxford, using the Great Western Main Line as far as Didcot and South West Trains operate a limited number of trains between Bath and Bristol.

Great Western Railway also operate a train between London Paddington – Cardiff Central every 30 minutes, with hourly extensions to Swansea. At Swansea/Cardiff there is a connecting Arriva Trains Wales boat train to/from Fishguard Harbour for the Stena Line ferry to Rosslare Europort in Ireland. An integrated timetable is offered between London Paddington and Rosslare Europort with through ticketing available.[12] Daytime and nocturnal journeys are offered in both directions daily (including Sundays). Additionally, 2–3 Great Western Railway trains continue to Pembroke Dock on weekends during the Summer season to connect with ferry services to Ireland.


Between London and Didcot there are four tracks, two for each direction. The main lines are mostly used by the faster trains and are on the south side of the route. The relief lines on the north side are used for slower services and those that need to call at all stations as only London Paddington, Slough, Maidenhead, Twyford, Reading and Didcot Parkway stations have platforms on the main lines (although a few others have main line platforms that can be used in an emergency). Between Didcot and Royal Wootton Bassett there are a series of passing loops lines to allow fast trains to overtake slower ones. This section is also signalled for bi-directional running on each line but this facility is usually only used during engineering working or when there is significant disruption to traffic in one direction.[13]

The line electrified for 12 miles using 25 kV AC overhead supply lines between Paddington and Airport Junction (the junction with the line to London Heathrow Airport west of Hayes & Harlington).[14]

The line speed is 125 miles per hour (201 km/h).[15] The relief lines from Paddington to Didcot are limited to 90 miles per hour (140 km/h) as far as Reading, and then 100 miles per hour (160 km/h) to Didcot. Lower restrictions apply at various locations.[13] The line is one of two Network Rail-owned lines equipped with the Automatic Train Protection (ATP) system, the other being the Chiltern Main Line.[16]

Planned developments

Since 2011, the Great Western has been undergoing a £5 billion modernisation by Network Rail.[17]

Reading railway station saw a major redevelopment with new platforms, a new entrance, footbridge and lifts; the work was completed a year ahead of schedule[18] in July 2014.[19][20]

Swansea railway station is to undergo renovation which will include an enlarged concourse, a new entrance and a new partition wall between concourse and platforms, together with a new cafe and more shops.[21][22]

Electrification west of Airport Junction

As part of Crossrail the Great Western was already planned to be electrified from Airport Junction to Maidenhead but, following a number of announcements and delays, the government announced in March 2011 that the line would be electrified between London and Cardiff together with the section linking Bristol Parkway and Bristol Temple Meads.[23][24] In July 2012, the government announced that the final portion of the Great Western, from Cardiff to Swansea, would be electrified.[25]

In addition to allowing Crossrail services with the new Class 345 EMUs, the electrification will also accommodate Great Western Railway's Class 387 EMUs. It was originally planned to bring second-hand units from Thameslink and Great Northern after the arrival of their new Class 700 trains[26] but it was later decided to order new Class 387s for GWR instead. Eight were delivered during 2016, with more on order to bring the total to 45. The Class 165 and Class 166 DMUs currently used by GWR for Thames Valley services will be displaced to services on the lines around Cardiff and Bristol, and the coastal routes around Devon and Cornwall.[27]

The line will also be used by the new Hitachi Super Express high speed trains – the Class 800s, 801s and 802s – which will gradually replace the InterCity 125 sets currently used for the long-distance services.

Other proposals

Network Rail plans to install European Rail Traffic Management System (ERTMS) in-cab signalling on the Great Western line;[28][29] this is a pre-requisite for the Super Express trains to run at 140 mph (225 km/h).[30] Some or all of the resignalling work will be done during the electrification work.[28]

Further capacity improvements are also scheduled at Swindon, adding to recent changes and the new Platform 4.

Crossrail services are planned to terminate at Reading. Some of the current suburban services into London Paddington are planned to be transferred to the new Crossrail service, which will in turn free up some surface-level capacity at London Paddington.[28]

Other more distant aspirations include resignalling and capacity improvements at Reading; the provision of four continuous tracks between Didcot and Swindon (including a grade-separated junction at Milton, where the down (westbound) relief line switches from the north side of the line to the south); and resignalling between Bath and Bristol to enable trains to run closer together.

Access to Heathrow Airport from the west remains an aspiration and the 2009 Heathrow Airtrack scheme, abandoned in 2011, proposed a route south of the Great Western Main Line to link the airport with Reading. Plans for electrification of the line will make it easier to access Heathrow from Reading, since lack of electrification between Reading station and Airport Junction (near West Drayton station) was a limiting factor.[28] Plans under consideration in 2014 included new tunnels between Heathrow and Langley.[31]

Network Rail intends to replace the ATP system with ETCS – Level 2[32] from 2017 to 2035 along with the introduction of the new IEP trains.

Signalling Solutions is to resignal the 12 miles from Paddington to West Drayton, including the Airport branch, as part of the Crossrail project.[33]

Calls for station reopenings

There are calls for the reintroduction of a station at Corsham due to recent growth of the town.[34] The original station was closed to passengers in 1965.

A local group is campaigning for the reopening of Saltford station between Bath and Bristol, to coincide with electrification.[35]

There have also been calls to reopen the former Wantage Road station.[36] Oxfordshire County Council include a proposal for a new station to serve for Wantage and Grove in their 2015-2031 local transport plan.[37]

Major incidents


  1. Bowen, Douglas John (1 December 2014). "Hitachi Rail Europe taps Huber+Suhner". Railway Age. Retrieved 2 December 2014.
  2. Network Rail (June 2011). "Modernising the Great Western" (PDF). Retrieved 24 August 2016.
  3. 1 2 Sanderson et al. 2012, p. 6.
  4. Collins, R.J. "High speed track on the Western Region of British Railways". Institute of Civil Engineers. Retrieved 18 May 2009.
  5. Anonymous (Winter 1979). Railway Electrification. British Railways Board (Central Publicity Unit). pp. 0–2, 8.
  6. "First Great Western Customer Panel" (PDF). First Great Western. Retrieved 24 November 2008.
  7. "West Coast dominates timetable changes". Modern Railways. Ian Allan Publishing. 65 (723): 46–50. 2008. ISSN 0026-8356.
  8. Sanderson et al. 2012.
  9. Sanderson et al. 2012, MLN1 10605, MLN1 10605, MLN1 10605, MLN1 10610, MLN1 10614, MLN1 10618.
  10. Sanderson et al. 2012, MLN1 0000 , MLN1 0742, MLN1 11725, MLN1 11826.
  11. "2007 Business Plan" (PDF). Retrieved 2013-09-16.
  12. "Sail and Rail to Britain | Train and Ferry Travel to England & Wales | Stena Line". Retrieved 2013-09-16.
  13. 1 2 "Route Plans 2007 Route 13 Great Western Main Line" (PDF). Network Rail. Retrieved 20 December 2015.
  14. "Britain's Transport Infrastructure Rail Electrification" (PDF). Department for Transport. Retrieved 20 December 2015.
  15. "About Great Western Main Line". Agility Trains. Retrieved 20 December 2015.
  16. "Great Western Main Line ATP Pilot Scheme". Train Testing. Retrieved 20 December 2015.
  17. Network Rail 2011, p. 8.
  18. "Reading rail station revamp 'a year ahead of schedule'". BBC. Retrieved 11 December 2015.
  19. "£425M transformation planned at Reading".
  20. Queen opens revamped Reading station BBC News 17 July 2014
  21. "City rail station to be revamped". BBC News. 8 February 2010. Retrieved 24 May 2010.
  22. "Transformation of Swansea Station unveiled". 2010-02-08. Retrieved 2013-09-16.
  23. "Great Western electrification and IEP to go ahead". RailNews.
  24. Network Rail 2011, p. 9.
  25. Woodman, Peter (16 July 2012). "£4.2bn of new rail schemes unveiled". The Independent. Press Association.
  28. 1 2 3 4 "DfT Rail Electrification paper" (PDF). Retrieved 2013-09-16.
  29. Network Rail 2011, p. 11.
  30. See Hitachi Super Express article
  31. "Heathrow rail link plan unveiled by Network Rail". BBC News. BBC. 6 February 2014. Retrieved 11 April 2015.
  32. "Network Rail Train Infrastructure Interface Specification" (PDF). Retrieved 2013-09-16.
  33. Nigel Harris, ed. (1–14 June 2011). "GWML signalling contract signed". RAIL (671): 17.
  34. Hicks, Amber (30 October 2014). "Corsham Station campaigners meet Department for Transport officials". Wiltshire Times. Newsquest (Oxfordshire and Wiltshire Ltd.). Retrieved 11 April 2015.
  35. "Rail-ly good news over station plan for Saltford". Bath Chronicle. Local World. 13 December 2014. Retrieved 11 April 2015.
  37. Connecting Oxfordshire: Local Transport Plan 2015-2031
  38. "Thames Trains fined £2m for Paddington crash". The Guardian. 5 April 2004.
  39. "Paddington crash prompts £4m fine". BBC News Online. 30 March 2007.


Further reading

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