The Tower Subway is a tunnel beneath the River Thames in central London, between Tower Hill on the north bank of the river and Vine Lane (off Tooley Street) on the south. In 1869 a 1,340-foot-long (410 m) circular tunnel was dug through the London clay using a cast iron circular shield independently invented and built by James Henry Greathead, similar to an idea that had been not received a patent in 1864, nor built by Peter W. Barlow.[1]
A 2 ft 6 in (762 mm) narrow gauge railway was laid in the tunnel and from August 1870 a cable-hauled wooden carriage conveyed passengers from one end to the other. This was uneconomic and the company went bankrupt by the end of the year. The tunnel was converted to pedestrian use and one million people a year crossed under the river, paying a toll of a ha'penny. The opening of the toll-free Tower Bridge nearby in 1894 caused a drop in income and the tunnel closed in 1898, after being sold to the London Hydraulic Power Company. Today the tunnel is used for water mains and telecommunications cables.
The same shield method of construction was used in 1890 to dig the tunnels of the City and South London Railway, the first of London's electrified "Tube" railways and the first underground electrified railway in the world.[2]
- ^ Copperthwaite, William Charles (1906). "The Shield: Its Early History, 1818 to 1880". Tunnel shields and the use of compressed air in subaqueous works (1 ed.). New York: Van Nostrand Co. p. 20. hdl:2027/uc2.ark:/13960/t2r49hs0g. Retrieved 21 May 2018.
- ^ Wright, Laurence (24 July 2017). "James Henry Greathead and the London Underground". Literator. 38 (1): 12. doi:10.4102/lit.v38i1.1324.