Thames Tunnel

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The Thames Tunnel is a tunnel, 35 feet wide and 1,300 feet long, beneath the River Thames in London, between Rotherhithe and Wapping. Originally designed for but never used by horse-drawn carriages, it is currently used by trains of the London Underground's East London Line. It was built by Marc Isambard Brunel and his son Isambard Kingdom Brunel in the 19th century.

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History and Development

A previous attempt at construction by Cornish miners, including Richard Trevithick, failed in 1808 due to the difficult conditions of the ground within 200 feet of the opposite bank. Marc Brunel's approach at the start of the project in 1825 was to construct a large shaft on the south bank at Rotherhithe. He did this by first assembling an iron ring 50 feet in diameter above ground. While a brick wall was built on top of this the earth below the ring's sharp lower edge was removed. The whole shaft thus gradually sank under its own weight.

Brunel and Thomas Cochrane devised the tunnelling shield to dig the tunnel. The Illustrated London News of 25 March 1843 described how it worked: Image:Thames tunnel shield.png

"The mode in which this great excavation was accomplished was by means of a powerful apparatus termed a shield, consisting of twelve great frames, lying close to each other like as many volumes on the shelf of a book-case, and divided into three stages or stories, thus presenting 36 chambers of cells, each for one workman, and open to the rear, but closed in the front with moveable boards. The front was placed against the earth to be removed, and the workman, having removed one board, excavated the earth behind it to the depth directed, and placed the board against the new surface exposed. The board was then in advance of the cell, and was kept in its place by props; and having thus proceeded with all the boards, each cell was advanced by two screws, one at its head and the other at its foot, which, resting against the finished brickwork and turned, impelled it forward into the vacant space. The other set of divisions then advanced. As the miners worked at one end of the cell, so the bricklayers formed at the other the top, sides and bottom."

The key innovation of the tunnelling shield was its support for the unlined ground in front and around it to reduce the risk of collapses. The shield was 35 feet wide and 20 feet 6 inches high (Trevithick's tunnel, in comparison, only measured 2-3 feet by 5 feet). Workers, including Brunel himself, soon fell ill from the poor conditions caused by filthy water seeping through from the river above. When the resident engineer, William Armstrong, fell ill in April 1826 Marc's son Isambard Kingdom Brunel took over at the age of just 20.

Image:Thamestunnel1840.jpg Work was slow, progressing at only 8-12 feet a week. To earn some money from the tunnel the company directors allowed sightseers to view the shield in operation. An estimated 600-800 visitors per day paid 1 shilling for the adventure. When on 18 May 1827 the tunnel flooded, Isambard Kingdom Brunel lowered a diving bell from a boat to repair the hole at the bottom of the river. Following the repairs and the drainage of the tunnel, he held a banquet inside it.

The tunnel was flooded again the following year, 12 January 1828, when six men died and Isambard Kingdom Brunel narrowly escaped drowning. After this setback the project was abandoned for seven years, until Marc Brunel succeeded in raising sufficient money to continue work. Impeded by further floods and gas leaks (methane and hydrogen sulfide), it was not completed until 1842. It was finally opened to the public on 25 March 1843.

The tunnel was not, however, a financial success and soon acquired an unpleasant reputation due to its adoption by London's prostitutes as a place of business. Nathaniel Hawthorne, writing in 1855, commented:

"It consisted of an arched corridor of apparently interminable length, gloomily lighted with jets of gas at regular intervals ... There are people who spend their lives there, seldom or never, I presume, seeing any daylight, except perhaps a little in the morning. All along the extent of this corridor, in little alcoves, there are stalls of shops, kept principally by women, who, as you approach, are seen through the dusk offering for sale ... multifarious trumpery ... So far as any present use is concerned, the tunnel is an entire failure."

Image:ThamesTunnelFromWapping.jpg In 1865 the tunnel was bought by the East London Railway Company and was adapted for trains, which ran out of Liverpool Street station. It was subsequently absorbed into the London Underground. In 1995 it became the focus of considerable controversy when the tunnel was closed for long-term maintenance,with the intention of sealing it against leaks by "shotcreting" it. This led to a legal conflict with architectural interests wishing to preserve the tunnel's appearance and disputing the need for the treatment. Following an agreement to leave a short section at one end of the tunnel untreated, and more sympathetic treatment of the rest of the tunnel, the work went ahead and the route reopened - much later than originally anticipated - in 1998.

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Visiting

Nearby is the Brunel Engine House which is open to visitors as a museum. It was originally built to house the draining pumps for the tunnel and has now been restored. During the year the museum organises "tunnel tours" when the lights in the tunnel are switched on and there is a rare chance to get a good view of the arches from a train.

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