Crossrail is not part of the the London Underground and uses its own tunnels. The trains will be longer, fatter and use overhead electrification instead of the

Crossrail is not part of the the London Underground and uses its own tunnels. The trains will be longer, fatter and use overhead electrification instead of the third rail used on the underground. Although the same signalling system is being installed on some of the London Underground. Outside of the central section it runs on existing mainline tracks on the Great Western and Great Eastern which both had different legacy systems.