The sixth and seventh Crossrail TBMs are on their way to the UK after undergoing factory tests in Germany.
Both machines are now being dismantled at the Herrenknecht factory before they are transported to Rotterdam, where they will travel by ferry to Tilbury, Essex.
Once in she arrives in London, TBM 6, Mary, will drill a tunnel under the Thames from Plumstead to North Woolwich alongside her sister machine Sophia, who commenced tunnelling at the start of January.
TBM 7 will be used on the drive from Pudding Mill Lane to Stepney Green, which will start in the summer.
All the machines’ components are expected to arrive at Crossrail’s sites within the next month.
Andrew Mitchell, Crossrail programme director said: “Over 4 km of tunnel has now been constructed on Crossrail.
“With tunnelling now well underway, we are looking forward to welcoming our sixth and seventh tunnel boring machines to the project.
“Once we’ve unpacked and reassembled them, they’ll begin drilling yet more tunnels underneath the streets of the capital.”
Crossrail’s final tunnel boring machine, TBM 8, will complete factory testing this summer.
