Hugh Pickens writes “BBC reports that the first of eight highly specialized Tunnel Boring Machines (TBM), each weighing nearly 1,000 tonnes, is being positioned at Royal Oak in west London where it will begin its slow journey east, carving out a new east-west underground link that will eventually run 73 miles from Maidenhead and Heathrow in the west, to Shenfield and Abbey Wood in the east. Described as ‘voracious worms nibbling their way under London,’ the 150-meter long machines will operate 24 hours a day and move through the earth at a rate of about 100m per week taking three years to build a network of tunnels beneath the city’s streets. Behind a 6.2-meter cutter head is a hydraulic arm. Massive chunks of earth are fed via a narrow-gauge railway along the interior of the machine, which is itself on wheels as the machines are monitored from a surface control room which tracks their positions using GPS while hydraulic rams at the front keep them within millimeters of their designated routes. ‘It’s not so much a machine as a mobile factory,’ says Roy Slocombe adding that the machine is staffed by a 20-strong ‘tunnel gang’ and comes with its own kitchen and toilet. Meanwhile critics complain that the project is a peculiarly British example of how not to get big infrastructure schemes off the ground, because almost 30 years will have elapsed from its political conception in 1989 to its current projected completion date of 2018.”

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