Thames Tunnel

The Thames Tunnel is an underwater tunnel, built beneath the River Thames in London, connecting Rotherhithe and Wapping. It measures 35 feet (11 m) wide by 20 feet (6 m) high and is 1,300 feet (396 m) long, running at a depth of 75 feet (23 m) below the river surface measured at high tide. It was the first tunnel known to have been constructed successfully underneath a navigable river (although the Babylonians may have built the Euphrates Tunnel nearly 4,000 years earlier), and was built between 1825 and 1843 using Marc Isambard Brunel's and Thomas Cochrane's newly invented tunnelling shield technology, by Brunel and his son Isambard Kingdom Brunel.

The tunnel was originally designed for horse-drawn carriages, but was never used for that purpose. It now forms part of the London Overground railway network under ownership of Transport for London.

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.

In 1805–09 a group of Cornish miners, including Richard Trevithick, tried to dig a tunnel farther 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 feet (305 m) of a total of 1,200 feet (366 m) had been dug. It only measured 2–3 feet by 5 feet (61–91 cm by 1.5 m), and was intended as the 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".

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