Marc Isambard Brunel - Thames Tunnel

Thames Tunnel

In 1805 the Thames Archway Company was formed with the intention of driving a tunnel beneath the Thames between Rotherhithe and Limehouse. Richard Trevithick was engaged by the company to construct the tunnel. He used Cornish miners to work on the tunnel. In 1807 the tunnel encountered quicksand and conditions became difficult and dangerous. Eventually the tunnel was abandoned after more than 1,000 feet had been completed, and expert opinion, led by William Jessop, was that such a tunnel was impracticable.

Brunel had already drawn up plans for a tunnel under the River Neva in Russia, but this scheme never came to fruition. In 1818 Brunel had patented a tunnelling shield. This was a reinforced shield of cast iron in which miners would work in separate compartments, digging at the tunnel-face. Periodically the shield would be driven forward by large jacks, and the tunnel surface behind it would be covered with cast iron lining rings. It is claimed that Brunel found the inspiration for his tunnelling shield from the shipworm, Teredo navalis, which has its head protected by a hard shell whilst it bores through ships' timbers. Brunel's invention provided the basis for subsequent tunnelling shields used to build the London Underground system and many other tunnels. Brunel was so convinced that he could use such a tunnelling shield to dig a tunnel under the Thames, that he wrote to every person of influence who might be interested. At last in February 1824 a meeting was held and 2,128 shares at £50 each were subscribed for. In June 1824 the Thames Tunnel Company was incorporated by royal assent. The tunnel was intended for horse-drawn traffic.

Work began in February 1825, by sinking a 50 feet (15 m) diameter vertical shaft on the Rotherhithe bank. This was done by constructing a 50 feet (15 m) diameter metal ring, upon which a circular brick tower was built. As the tower rose in height, its weight forced the ring into the ground, and at the same time workmen excavated the earth in the centre of the ring. This vertical shaft was completed in November 1825, and the tunnelling shield, which had been manufactured at Lambeth by Henry Maudslay's company, was then assembled at the bottom. Maudslay also supplied the steam powered pumps for the project. The shield was rectangular in cross section, and consisted of twelve frames, side by side, each of which could be moved forward independently of the others. Each frame contained three compartments, one above the other, each big enough for one man to excavate the tunnel face, and the whole frame accommodated 36 miners. When enough material had been removed from the tunnel face, the frame was moved forward by large jacks. As the shield moved forward, bricklayers followed, lining the walls. The tunnel required over 7,500,000 bricks.