The approach to the tunnel.

The Severn Tunnel (Welsh: Twnnel Hafren) is a railway tunnel in the United Kingdom, linking South Gloucestershire in the west of England to Monmouthshire in south Wales under the estuary of the River Severn. It was built by the Great Western Railway between 1873 and 1886, and is 4 mi 624 yd (7008 m) long, and is still the longest mainline railway tunnel within the UK (though the Channel Tunnel is longer). Only 2¼ miles (3.62 km) of the tunnel are actually under the river. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Welsh redirects here, and this article describes the Welsh language. ... A disused railway tunnel now converted to pedestrian and bicycle use, near Houyet, Belgium A tunnel is an underground passage. ... South Gloucestershire is a local government area in South West England. ... Royal motto (French): Dieu et mon droit (Translated: God and my right) Englands location within the UK Official language English de facto Capital London de facto Largest city London Area - Total Ranked 1st UK 130,395 km² Population - Total (mid-2004) - Density Ranked 1st UK 50. ... Monmouthshire (Welsh: Sir Fynwy) is a traditional county and principal area in south-east Wales. ... National motto: Cymru am byth (Welsh: Wales for ever) Waless location within the UK Official languages English, Welsh Capital Cardiff Largest city Cardiff First Minister Rhodri Morgan Area  - Total Ranked 3rd UK 20,779 km² Population  - Total (2001)  - Density Ranked 3rd UK 2,903,085 140/km² Ethnicity: 97. ... Estuaries and coastal waters are among the most productive ecosystems on Earth, providing numerous ecological, economic, cultural, and aesthetic benefits and services. ... The Severn Bridges crossing near the mouth of the River Severn The River Severn (Welsh: Afon Hafren) is the longest British river, at 354 kilometres (219 miles) long; it rises at an altitude of 610 metres on Plynlimon near Llanidloes, in the Cambrian Mountains, Mid Wales, and it passes through... The original Bristol Temple Meads station, first terminus of the GWR, is the building to the left of this picture The Great Western Railway (GWR) was a British railway company, linking South West England, the West Country and South Wales with London. ... 1873 was a common year starting on Wednesday (see link for calendar). ... 1886 is a common year starting on Friday (click on link to calendar) // Events January 18 - Modern field hockey is born with the formation of The Hockey Association in England. ... Channel Tunnel The British terminal at Cheriton, from the Pilgrims Way The Channel Tunnel, (French: le tunnel sous la Manche; popularly nicknamed the Chunnel in English) is a 50-km-long (~31 imperial miles) rail tunnel beneath the English Channel at the Straits of Dover, connecting Cheriton in Kent, United...

Prior to the building of the tunnel, communications between the Bristol area and South Wales were primarily by boat. With the coming of the railway, services were forced to either take a long detour via Gloucester, or to transfer their passengers and cargo onto a ferry. The GWR proposed to drive a tunnel under "The Shoots", a relatively narrow but unusually deep section of the estuary. This meant steep gradients by railway standards in order to reach the required depth. Bristol is an English city and county and one of the three administrative centres of South West England (the others being Plymouth and Exeter). ... Gloucester (pronounced ) is a city and district in south-west England, close to the Welsh border. ... The Pride of Burgundy, a P&O Ferries car ferry on the Dover-Calais route A ferry is a boat or a ship carrying passengers, and sometimes their vehicles, on scheduled services. ...

Work on the tunnel began in March 1873, and proceeded gradually through the 1870s. As Thomas Walker notes in his book, GWR had expected the critical part of the work to be the tunnelling under the deep-water channel of the Shoots. However, the builders' real difficulties began in October 1879. At this stage, when only 130 yards remained separating the main tunnel heading being driven from the Welsh side, and the shorter Gloucestershire heading, the workings were inundated, from a large fresh-water source ("The Great Spring") tapped by the heading being driven inland on the Welsh side. 1879 was a common year starting on Wednesday (see link for calendar). ...

Thomas A. Walker was the contractor entrusted by the chief GWR engineer Sir John Hawkshaw with rescuing and completing the tunnel after the 1879 flooding. Holding the Great Spring in check required the installation of greatly increased pumping facilities, and a diver had to be sent down a shaft and 300 m along the tunnel heading to close a door in the workings and seal off the waters. Work in the area of the Great Spring was unable to continue until January 1881. Work was later disrupted by further flooding from the Great Spring, a large tidal wave and a breakthrough of the bed of a pool (the "Salmon Pool") on the English side. In the intervening period the Severn Railway Bridge from Sharpness to Lydney was opened. Sir John Hawkshaw (1811 - June 2, 1891), English engineer, was born in Yorkshire, and was educated at Leeds grammar school. ... 1881 was a common year starting on Saturday (see link for calendar). ... The Severn Railway Bridge was a bridge in Gloucestershire that used to cross the tidal River Severn and went from Sharpness to Lydney. ... This article refers to the English port of Sharpness. ... Location within the British Isles. ...

The tunnel was completed during 1885 and a goods train passed through it on January 9, 1886, but regular services had to wait until the pumping systems were complete. The tunnel opened to goods trains in September and to passenger traffic in December 1886, nearly 14 years after work had started. Fixed steam engines pumped out the Great Spring and other sources of water until the 1960s, when they were replaced by electrically powered pumps. January 9 is the 9th day of the year in the Gregorian calendar. ... 1886 is a common year starting on Friday (click on link to calendar) // Events January 18 - Modern field hockey is born with the formation of The Hockey Association in England. ... A steam engine is a heat engine that makes use of the thermal energy that exists in steam, converting it to mechanical work. ... The 1960s in its most obvious sense refers to the decade between 1960 and 1969, but the expression has taken on a wider meaning over the past twenty years. ...

The Second Road Crossing (usually but slightly misleadingly called the Second Severn Crossing), which passes above the tunnel, crosses over it on a "ground level bridge" on the English side, (near the Salmon Pool), supported in such a way that no load is imposed on the tunnel. The opportunity was taken to renew the concrete cap above the tunnel in the Salmon Pool during bridge-construction. The Severn crossing consists of two river crossings over the River Severn between England and Wales. ...

There is also a second tunnel under the river just upstream near this point, carrying a high-capacity electricity cable (SuperGrid) under the river, and complementing the earlier high-capacity link, which is slung high over the river (just downstream of the first road bridge). Both electricity links were originally commissioned by the CEGB. The Central Electricity Generating Board (CEGB) was the cornerstone of the British electricity industry for almost 50 years, from its nationalisation in 1947 to privatisation in the 1990s. ...

References

• The Severn Tunnel: Its Construction and Difficulties (1872-1887) by Thomas A. Walker ISBN 1850260141 (1st edition 1888) reprinted edition 2004, Nonsuch Publishing Ltd, Stroud, England ISBN 1-84588-000-5 . (Walker was the contractor entrusted by the chief GWR engineer Sir John Hawkshaw with rescuing and completing the tunnel after the 1879 flooding).

Sir John Hawkshaw (1811 - June 2, 1891), English engineer, was born in Yorkshire, and was educated at Leeds grammar school. ...

External links

• History of the tunnel from the Great Western Archive