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"Whilst the Crossrail TBMs are not as big as the largest yet, which was over 19 metres in diameter and drove a tunnel in St Petersburg, Russia, they are massive. Each is over 100 metres long and weighs about 1,000 tonnes.
"They are operated by 20 people, 12 on board the TBM and eight in the tunnel behind it. Typically a rate of 100 metres per week is being achieved on the Crossrail tunnels, with a total of eight machines being needed to create the 42km of rail tunnels on the whole project. TBMs Phyllis and Ada, working on the western tunnels, have peaked at speeds of around 215 metres per week."
"... Today’s TBMs are an amazing contrast with the techniques used by Brunel for the first Thames tunnel, not far away from the current site."