Crossrail will cost almost £15bn and by linking areas east and west of the capital, will increase the city's rail capacity by 10%.
The company has just unveiled the giant tunnelling machines which will start work in March, and has started production of the tunnel liners at a factory in west London.
To construct the 21km of twin-bore tunnel required for Crossrail, eight tunnel boring machines will be required and will undertake ten individual tunnel drives to construct the 6.2m diameter tunnels. At 140 metres, each TBM would just fit just inside the boundaries of a cricket oval.
The TBMs will run 24 hours a day, 7 days a week stopping only for scheduled maintenance.
As the TBMs advance forward, precast concrete segments will be built in rings behind the TBMs. Construction of the concrete segment factory for the western running tunnels between Royal Oak and Farringdon is now complete at Old Oak Common. The plant will begin manufacturing over 70,000 segments for the western tunnels from this month.
http://www.bbc.co.uk/news/uk-16289051
