Tunnel vision: London’s Crossrail enters its final leg

Tunnel vision: London’s Crossrail enters its final leg

Under 2km of tunnels remain of the 42km needed for the £14.8bn infrastructure project, due to be finished in 2017

Elizabeth, one of the last tag team of Crossrail tunnelling machines, has made the first breakthrough into the City of London, 40 metres below ground under Liverpool Street. The moment when the 6.2 metre-wide drill head cut through the wall into the hollowed-out future station marked the start of the final phase of excavation for the £14.8bn project, with just under 2km remaining of the 42km of tunnels to be dug under the capital. The final link-up of all the tunnels will be achieved in the spring, fittingly, by sister machine Victoria at Farringdon: the destination of the world’s very first underground train in the last queen’s reign, 152 years ago.

Tunnelling technology has moved on somewhat since then, but the crew of 20 on each tunnel-boring machine still have an uncomfortable, difficult task, working 12-hour shifts around the clock. Their workplace is essentially a mobile, underground factory, located claustrophobically at what was, until the breakthrough, a 7km-long dead end. Behind the slowly turning cutter head is a 148-metre-long train of hydraulic rams, control rooms, conveyors, piping and steel walkways, creating a tunnel and laying tracks while spewing out the London clay behind. Seated at a computer console near the front, a controller monitors an array of panels to guide the machine forward, a 1,000-tonne monster that must not deviate inches from its precise path through a subterranean warren.

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Source: Guardian Transport

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