The first 10km of permanent track has been laid on the Elizabeth line in a tunnel under the Royal Docks.
Transport minister Lord Ahmed visited the nearby Custom House station and saw how a fleet of customised machinery had laid the track.
He said: “The scale of engineering that will deliver the Elizabeth line is incredible and the laying of track is a significant milestone for this next phase of the project."
Installation of the permanent tracks is part of Crossrail’s railway systems works to fit out the new tunnels, stations and portals ahead of TfL-run services starting in 2018.
A team of more than 1,200 is delivering this phase of the Crossrail project which includes the design, installation and testing of track, electrical systems, platform screen doors, signalling and communications along with cabling, lighting and power.
Some 57km of long welded permanent rail have been manufactured by Tata Steel in Scunthorpe with around 7,000 sleepers manufactured by SBC Rail in Nottingham.
The rails are delivered in 108m long sections and transported into the new tunnels by one of four Multi Purpose Gantries (MPGs) which have been specifically designed for the Crossrail project.
Each MPG travels along the raised curbs of the tunnel and carefully positions the sleepers at precise intervals before lifting and positioning the rails on top. Each section will be secured and welded ahead of the 465m long concreting train – a mobile concrete batching factory – concreting them in place. More than 34,000 cubic metres of concrete will be used to build the track as part of the fit-out the Crossrail tunnels.