The machines, which will bore the tunnels under the Chilterns, are being built by Herrenknecht in Germany.
Last week we reported that HS2 Ltd is asking the public to vote for what they should be named, out of a shortlist of Cecilia, Florence and Marie.
After completion, the first two machines will be disassembled before being shipped to Britain and reassembled on site.
Together the TBMs will spend three and a half years excavating what will be the longest and deepest tunnels on the project, stretching from just inside the M25 to South Heath in Buckinghamshire, down to depths of 80 metres. They will be operated by Align JV, a joint venture of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick.
The TBMs are 170 metres long and weigh roughly 2,000 tonnes each. The cutterhead of each is 10.26 metres diameter. The internal diameter of the tunnels in which the trains will pass through will be 9.1 metres.