Great Western Main Line

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 1841. The final section, between Chippenham and Bath, was opened on completion of the Box Tunnel in June 1841.[3]

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+1⁄2 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 (October 1861), Reading to Didcot (December 1856), Didcot to Swindon (February 1872), Swindon to Thingley Junction, Chippenham (June 1874), Thingley Junction to Bathampton (March 1875), Bathampton to Bristol (June 1874), Bristol station area (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 bit wider than usual, or where tracks are ten feet apart instead of the usual six.

The original dual tracks were widened to four in places, mainly in the east half, between 1877 and 1899: Paddington to Southall (October 1877), Southall to West Drayton (November 1878), West Drayton to Slough (June 1879), Slough to east side of Maidenhead Bridge (September 1884), Maidenhead Bridge to Reading (June 1893), Reading station (1899), Reading to Pangbourne (July 1893), Pangbourne to Cholsey and Moulsford (June 1894), Cholsey and Moulsford to Didcot (December 1892); also short sections between Didcot and Swindon, and at Bristol.

Following the Slough rail accident of 1900, in which 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 and more widening work took place between 1931 and 1932.[4]

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. The companies 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 (BR) in 1948.

The line speed was upgraded in the 1970s to support the introduction of the InterCity 125 high speed train (HST).[5]

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 line from Paddington to Swansea by 2000.[6] Under the 1979–90 Conservative governments that succeeded the 1976–79 Labour government, the proposal was not implemented.

In the mid 1990s, the line between London Paddington and Hayes & Harlington was electrified as part of the Heathrow Express project.[7]

In August 2008, it was announced that a number of speed limits on the relief lines between Reading and London had been raised, so that 86% of the line could be used at 90 mph (140 km/h).[8]

Partial electrification by 2019 allowed replacement of InterCity 125 and Class 180 sets by new Hitachi Super Express high speed trains – the Class 800s and Class 802s. It also allowed the introduction of Class 387 EMUs by GWR on shorter-distance services.[9]

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 Maidenhead Railway Bridge. Between Chippenham and Bath the line passes through Box Tunnel, and then follows the valley of the River Avon.

A junction west of Swindon allows trains to reach Bristol by an alternative route along the South Wales Main Line. Other diversionary routes exist between Chippenham and Bath via the Wessex Main Line, although this involves a reversal at Bradford Junction; and from Reading to Bath via the Berks and Hants Line.

Most services are provided by Great Western Railway (GWR). The stations served by trains between London Paddington and Bristol Temple Meads are Reading, Didcot Parkway, Swindon, Chippenham, and Bath Spa. Some trains between London and Bristol do not call at Didcot Parkway.

The Elizabeth line runs on the Great Western Main Line between London and Reading.

Fast trains from Paddington to London Heathrow Airport are operated by Heathrow Airport Holdings as the Heathrow Express.

CrossCountry operate trains between Reading and Oxford, using the Great Western Main Line as far as Didcot and South Western Railway 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 Transport for 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.[13] Daytime and nocturnal journeys are offered in both directions daily (including Sundays).

St James Railway Bridge, Bath

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 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, a series of passing loops allow fast trains to overtake slower ones. This section is 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.[14]

The summit of the line is at Swindon, and falls away in each direction: Swindon is 270 feet (82 m) above Paddington, and 292 feet (89 m) above Bristol Temple Meads. The maximum gradient between Paddington and Didcot is 1 in 1320 (0.75 ‰ or 0.075%); between Didcot and Swindon it is 1 in 660 (1.5 ‰ or 0.15%) but west of Swindon, gradients as steep as 1 in 100 (10 ‰ or 1%) are found in places, such as Box Tunnel and to the east of Dauntsey.[15][16]

The line is electrified between Paddington and Langley Burrell (just east of Chippenham) using 25 kV AC overhead supply lines; the Reading to Taunton line (as far as Newbury) and the South Wales Main Line (as far as Cardiff Central) are also electrified.

The line speed is 125 mph (201 km/h).[17] The relief lines from Paddington to Didcot are limited to 90 mph (140 km/h) as far as Reading, and then 100 mph (160 km/h) to Didcot. Lower restrictions apply at various locations.[14] 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.[18]

Since 2011, the Great Western has been undergoing a £5 billion modernisation by Network Rail.[21]

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[22] in July 2014.[23][24]

• Slough rail accident – 16 June 1900 – An express train from Paddington to Falmouth Docks ran through two sets of signals at danger and collided with a local train heading for Windsor. Five passengers were killed and 35 seriously injured.
• Ealing rail crash – 19 December 1973 – A train from Paddington to Oxford derailed after a loose battery box cover on the Class 52 "Western" locomotive hauling the train struck lineside equipment, causing a set of points to move under the train. Ten passengers were killed and 94 injured.
• Southall rail crash – 19 September 1997 – An InterCity 125 service from Swansea to Paddington, operated by Great Western Trains, failed to stop at a red signal and collided with a freight train entering Southall goods yard. Seven people were killed and 139 were injured. The incident severely damaged public confidence in the safety of the rail system. It was found that the train's automatic warning system (AWS) was faulty, and the driver had been distracted (he had bent down to pack his bag). Great Western Trains was fined £1.5 million for violations of health and safety law in connection with the accident.
• Ladbroke Grove rail crash – 5 October 1999 – A Thames Trains service from Paddington to Bedwyn passed a signal at danger at the gantry protecting a main set of (crossover) points between the one-way and bi-directionally used lines. The train ran the wrong way down the line and was hit head-on by a First Great Western HST service from Cheltenham Spa to Paddington at a closing speed of approximately 130 mph (210 km/h). 31 people died, including both drivers, with more than 520 people injured. Thames Trains was fined £2 million for violations of health and safety law.[41] Railtrack pleaded guilty to charges under the Health and Safety at Work Act 1974 in relation to the accident. It was subsequently fined £4 million and was also ordered to pay £225,000 in costs.[42]

The reference for the route map diagram is:- Jowett, Alan (March 1989). Jowett's Railway Atlas of Great Britain and Ireland: From Pre-Grouping to the Present Day (1st ed.). Sparkford: Patrick Stephens Ltd. pp. 113, 115a, 116, 118b, 118d, 120, 124–25. ISBN 978-1-85260-086-0. OCLC 22311137.

• East Coast Main Line
• West Coast Main Line
• Midland Main Line
• Highland Main Line

• Pre-grouping Atlas and Gazetteer. Shepperton: Ian Allan Limited. 1976. ISBN 0-7110-0320-3.
• MacDermot, E T (1931). History of the Great Western Railway, volume II 1863-1921. London: Great Western Railway.

Wikimedia Commons has media related to Great Western Main Line.

• Paddington, Reading General, Didcot and Milton (British Railways in the 1960s Sectional Appendix Extract) (via The Internet Archive)
• Reading, Main Line West and Bedwyn (British Railways in the 1960s Sectional Appendix Extract) (via The Internet Archive)