Nick Cooper - London Underground at War

Cut-and-cover sub-surface construction of the Metropolitan line passing Kings Cross in 1861. (JC)

The line was ready by the end of 1862 and after the customary inspection and approval by the Board of Trade and a few days of trial working, the Metropolitan Railway opened for passenger traffic on Saturday 10 January 1863. The opening had been celebrated the previous Friday, but one conspicuously absent guest was Charles Pearson, who did not live to see his dream of an underground railway become reality, having died just four months previously.

Short though the original section of the Metropolitan was, by the end of 1864 it had been extended westward and then south to both South Kensington and Hammersmith, with a branch off the latter to Kensington (Addison Road). The following year saw an eastern extension to Moorgate Street and by the end of the decade a branch at Baker Street was making a tentative move into the north-western suburbs, reaching Swiss Cottage. To the south, the Metropolitan District Railway had opened between West Brompton and Blackfriars stations, with a link to the Metropolitan line proper at Brompton Road.

The rapid expansion of these sub-surface lines continued over the next twenty years until, by 1890, they had between them reached as far south as Wimbledon and Richmond, west to Hounslow and Ealing (from which a service to Windsor lasted two-and-a-half years before proving a bit too far) and north to Chesham. In the east, the acquisition and re-purposing of the pedestrian Thames Tunnel it was the first tunnel in the world built under a wide river took both Metropolitan and District trains to New Cross. These extensions ran almost exclusively on the surface, since tunnels were not necessary further out where land was cheaper, but 1890 saw the arrival of a new player using a very different method of tunnelling.

In the mid-1860s, the engineer James Barlow developed a simplified variation of Marc Brunels huge rectangular tunnelling shield, which had been used to construct the Thames Tunnel between 1825 and 1843. Rather than a brick tunnel, Barlows would be composed of a series of 8-foot diameter rings formed from prefabricated curved cast iron segments, creating a continuous metal tube in which the track-bed would be laid; larger tubes would form the stations. When assembled, the outside diameter of the tunnels was slightly smaller than the circular tunnelling shield, so that the gap could be filled and sealed with liquid cement. This method of tube construction although much refined and now largely automated remains in use to this day.

Although Barlow could not raise enough interest in a full railway, he tried out the basic principles by building a subway under the Thames between Tower Hill and Southwark where there was no bridge at that time with himself as engineer and his pupil James Henry Greathead as contractor. At each end of the tunnel there was a steam-powered lift to carry passengers 50 feet down to, or up from, the single 10-foot-long car that ran from one side of the river to the other on 2-foot 6-inch gauge track. Steam-powered cable haulage was used to move the car.