Crossrail's giant tunnelling machines unveiled

Engineers are getting ready to start tunnelling beneath London in what has become Europe's biggest construction project.

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.

Richard Lister went to see them.