Thames Tunnel
Introduction
The Thames Tunnel is a tunnel beneath the River Thames in London, connecting Rotherhithe and Wapping. It measures 35 ft (11 m) wide by 20 ft (6.1 m) high and is 1,300 ft (400 m) long, running at a depth of 75 ft (23 m) below the river surface measured at high tide. It is the first tunnel known to have been constructed successfully underneath a navigable river. It was built between 1825 and 1843 by Marc Brunel, and his son, Isambard, using the tunnelling shield newly invented by the elder Brunel and Thomas Cochrane.
The tunnel was originally designed for horse-drawn carriages, but was mainly used by pedestrians and became a tourist attraction. In 1869 it was converted into a railway tunnel for use by the East London line which, since 2010, is part of the London Overground railway network under the ownership of Transport for London.
History
Construction
At the start of the 19th century, there was a pressing need for a new land connection between the north and south banks of the Thames to link the expanding docks on each side of the river. The engineer Ralph Dodd tried, but failed, to build a tunnel between Gravesend and Tilbury in 1799.
Between 1805 and 1809, a group of Cornish miners, including Richard Trevithick, tried to dig a tunnel further upriver between Rotherhithe and Wapping/Limehouse, but failed because of the difficult conditions of the ground. The Cornish miners were used to hard rock and did not modify their methods for soft clay and quicksand. This Thames Archway project was abandoned after the initial pilot tunnel (a 'driftway') flooded twice when 1,000 ft (300 m) of a total of 1,200 ft (370 m) had been dug. It only measured 2–3 ft (0.6–0.9 m) by 5 ft (1.5 m), and was intended as a drain for a larger tunnel for passenger use. The failure of the Thames Archway project led engineers to conclude that "an underground tunnel is impracticable".
The Anglo-French engineer Marc Brunel refused to accept this conclusion. In 1814 he proposed to Emperor Alexander I of Russia a plan to build a tunnel under the river Neva in St Petersburg. This scheme was turned down (a bridge was built instead) and Brunel continued to develop ideas for new methods of tunnelling.
Sources
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