The TBMs are being built by Herrenknecht AG and the first two will arrive in London in early 2012 ahead of being launched from Royal Oak in spring 2012.

Contractors chosen for the drives have been in charge of specifying the machines

Herrenknecht AG will deliver two TBMs to Royal Oak Portal for the western running tunnels in early 2012, two TBMs to Limmo Peninsula for the eastern running tunnels in mid 2012 and a further two machines to Stepney Green later in 2012.

Londoners will be given the chance to name the tunnel boring machines and will be able to follow their progress as they make their way under the capital via the Crossrail website.

To construct the 21km of twin-bored tunnel required for Crossrail, at least seven tunnel boring machines will be required and will undertake ten individual tunnel drives to construct the 6m diameter rail tunnels.

Consideration is currently being given to the need for a further TBM on the short tunnel drive between Limmo Peninsula and Victoria Dock Portal (Drive G).

The method of constructing this tunnel section is the subject of ongoing discussions with the tunnelling contractor Dragados/John Sisk.

The TBMs required for Crossrail will be up to 120m in length and weigh around 850 tonnes.

Rob Holden, Crossrail Chief Executive said: “In less than a year, the first tunnel boring machines will have arrived and begun their journey from Royal Oak to Farringdon.

“I’m delighted that Londoners will be given the chance to name the machines that will build the major new rail tunnels under London.

“Even though the start of tunnelling is still about nine months away, work has been ongoing since early 2010 to construct the tunnel portal at Royal Oak from where the first TBM will launch.”

The five tunnels to be constructed are:

• Royal Oak to Farringdon west (Drive X) – length of drive approximately 6.1 km
• Limmo Peninsula in the Royal Docks to Farringdon east (Drive Y) – length of drive approximately 8.3 km
• Stepney Green to Pudding Mill Lane (Drive Z) – length of drive approximately 2.7 km
• Limmo Peninsula in the Royal Docks to Victoria Dock Portal (Drive G) – length of drive approximately 0.9 km
• Plumstead to North Woolwich (Drive H) – length of drive approximately 2.6 km

Tunnel construction schedule: