Crossrail, Europe's largest infrastructure project, has reached the halfway point of its construction.
Seven 1,000 tonne tunnelling machines have bored over 29km of new 6.2m diameter tunnels under London, with an eighth machine due to launch next month.
Construction is also advancing on the ten new Crossrail stations and on works above ground west of Paddington and east of Stratford. 10,000 people are currently working on the project.
The £14.8 billion project will add 10% capacity to London's rail network. It will serve 38 stations, connecting Maidenhead and Heathrow in the west with Shenfield and Abbey Wood in the east via central London.
During 2014, Crossrail's major civil engineering and tunnelling works will conclude and the focus will shift towards station construction, fit-out and implementing railway systems within the tunnels and stations. The train operator will then test and refine the systems before trains run from 2018.