By the end of the 18th century, a tunnel under the Thames seemed a possible answer to London's pressing need for additional river crossings. However, many thought the idea was impossible. Up until then, tunnels had been driven only through hard rock, and no underwater tunnel had ever been built.
In 1818, the French emigre engineer Marc Isambard Brunel patented his tunnelling shield. This complicated structure consisted of twelve cast-iron frames, and it allowed workers to remove soft soil in relative safety. After removing 4.5 inches (11 cm) of soil, the shield would be pushed forward and the shaft behind would be lined with brick.
Work began on the tunnel between Wapping and Rotherhithe in 1825. Brunel had been joined by a new assistant - his son, Isambard Kingdom Brunel. As the Thames Tunnel was pushing the limits of what was possible, it was hardly surprising that accidents occurred. The worst was in 1828, when six men were drowned. Later that year, the work was halted when the money ran out. It resumed only in 1835.
It finally opened in 1843. Unfortunately, the shortage of funds meant the carriage ramps were never built, so only pedestrians could use the tunnel. Instead of becoming a vital artery between the port districts, it was merely an ornamental foot tunnel.
Although it was a technological wonder, it was a financial white elephant until 1869, when it was sold to the East London Railway Company. It is now part of London Underground’s East London Line, and carries trains between Rotherhithe and Wapping.