C H S Tupholme. This paper was first published in GE’s March 1969 edition.
The recently completed Victoria Line is the first deep-level tube railway to be built across the centre of London for 60 years, and runs from Victoria Station for 101/2 miles (16.9km) through London’s West End to Walthamstow in the northeastern suburbs. The average tunnel depth from ground surface to rail level is about 70 ft (21.3m); the average gradient is between 1:70 and 1:100,and no gradient is steeper than 1:40. Within three years from work starting on the first of the 21 shafts from which the running tunnels were driven, about 500,000 yd3 (382,280 m3) of earth was excavated from the 21 miles (33.8km) of 12 ft (3.66 m) diameter running tunnels alone. In addition, some 300,000 yd3 (229,360 m3) of earth has been removed during building of the 12 stations for the new line.