Construction Thames Tunnel

inside thames tunnel during construction, 1830

at start of 19th century, there pressing need new land connection between north , south banks of thames link expanding docks on each side of river. engineer ralph dodd tried, failed, build tunnel between gravesend , tilbury in 1799.

in 1805–09 group of cornish miners, including richard trevithick, tried dig tunnel farther upriver between rotherhithe , wapping/limehouse failed because of difficult conditions of ground. cornish miners used hard rock , did not modify methods soft clay , quicksand. thames archway project abandoned after initial pilot tunnel (a driftway ) flooded twice when 1,000 feet (305 m) of total of 1,200 feet (366 m) had been dug. measured 2–3 feet 5 feet (61–91 cm 1.5 m), , intended drain larger tunnel passenger use. failure of thames archway project led engineers conclude underground tunnel impracticable .

however, anglo-french engineer marc brunel refused accept conclusion. in 1814 proposed emperor alexander of russia plan build tunnel under river neva in st petersburg. scheme turned down (a bridge built instead) brunel continued develop ideas new methods of tunnelling.

brunel patented tunnelling shield, revolutionary advance in tunnelling technology, in january 1818. in 1823 brunel produced plan tunnel between rotherhithe , wapping, dug using new shield. financing found private investors, including duke of wellington, , thames tunnel company formed in 1824, project beginning in february 1825.

the first step construction of large shaft on south bank @ rotherhithe, 150 feet (46 m) river bank. dug assembling iron ring 50 feet (15 m) in diameter above ground. brick wall 40 feet (12 m) high , 3 feet (91 cm) thick built on top of this, powerful steam engine surmounting drive excavation s pumps. whole apparatus estimated weigh 1,000 tons. soil below ring s sharp lower edge removed manually brunel s workers. whole shaft gradually sank under own weight, slicing through soft ground rather enormous pastry cutter. shaft became stuck @ 1 point during sinking pressure of earth around held firmly in position. weight required make continue descent; 50,000 bricks added temporary weights. realised problem caused because shaft s sides parallel; years later when wapping shaft built, wider @ bottom top. non-cylindrical tapering design ensured did not stuck. november 1825 rotherhithe shaft in place , tunnelling work begin.

the tunnelling shield, built @ henry maudslay s lambeth works , assembled in rotherhithe shaft, key brunel s construction of thames tunnel. illustrated london news described how worked:

diagram of tunnelling shield used construct thames tunnel



a scale model of tunnelling shield @ brunel museum @ rotherhithe

the mode in great excavation accomplished means of powerful apparatus termed shield, consisting of twelve great frames, lying close each other many volumes on shelf of book-case, , divided 3 stages or stories, presenting 36 chambers of cells, each 1 workman, , open rear, closed in front moveable boards. front placed against earth removed, , workman, having removed 1 board, excavated earth behind depth directed, , placed board against new surface exposed. board in advance of cell, , kept in place props; , having proceeded boards, each cell advanced 2 screws, 1 @ head , other @ foot, which, resting against finished brickwork , turned, impelled forward vacant space. other set of divisions advanced. miners worked @ 1 end of cell, bricklayers formed @ other top, sides , bottom.

each of twelve frames of shield weighed on 7 tons. key innovation of tunnelling shield support unlined ground in front , around reduce risk of collapses. however, many workers, including brunel himself, fell ill poor conditions caused filthy sewage-laden water seeping through river above. sewage gave off methane gas ignited miner s oil lamps. when resident engineer, john armstrong of ingram northumberland , fell ill in april 1826 marc s son isambard kingdom brunel took on @ age of 20.

work slow, progressing @ 8–12 feet week (3–4 m). earn income tunnel, company directors allowed sightseers view shield in operation. charged shilling adventure , estimated 600–800 visitors took advantage of opportunity every day.

the excavation hazardous. tunnel flooded on 18 may 1827 after 549 feet (167 m) had been dug. isambard kingdom brunel lowered diving bell boat repair hole @ bottom of river, throwing bags filled clay breach in tunnel s roof. following repairs , drainage of tunnel, held banquet inside it.

1828

the tunnel flooded again following year, on 12 january 1828, when 6 men died. isambard extremely lucky survive this; 6 men had made way main stairwell, emergency exit known locked. isambard instead made locked exit. contractor named beamish heard him there , broke door down, , unconscious isambard pulled out , revived. sent brislington, near bristol, recuperate; there heard competition build became clifton suspension bridge.

financial problems followed, leading in august tunnel being walled off behind shield , abandoned 7 years.

re-opening

in december 1834 marc brunel succeeded in raising enough money (including loan of £247,000 treasury) continue construction.

starting in august 1835 old rusted shield dismantled , removed. march 1836 new shield, improved , heavier, assembled in place , boring resumed.

impeded further floods, (23 august , 3 november 1837, 20 march 1838, 3 april 1840) fires , leaks of methane , hydrogen sulphide gas, remainder of tunnelling completed in november 1841, after 5 , half years. extensive delays , repeated flooding made tunnel butt of metropolitan humour:

cutaway illustration of thames tunnel excavation around 1840

good monsieur brunel

let misanthropy tell

that work, half complete, begun ill;

heed them not, bore away

through gravel , clay,

nor doubt success of tunnel.

that mishap,

when thames forced gap,

and made fit haunt otter,

has proved scheme

is no catchpenny dream;—

they can t twill never hold water.

the thames tunnel fitted out lighting, roadways , spiral staircases during 1841–1842. engine house on rotherhithe side, houses brunel museum, constructed house machinery draining tunnel. tunnel opened public on 25 march 1843.