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Crossrail’s sixth and seventh tunnelling machines on their way to London

By Nick Mann

Crossrail’s sixth and seventh tunnelling machines on their way to London

Crossrail’s sixth and seventh tunnel boring machines (TBMs) have rolled off the production line and are set to start their journey to London.

Both machines have recently completed their factory testing at the Herrenknecht factory in Germany and are now in the process of being dismantled, boxed up and transported to Rotterdam, where they will be put on a ferry to Tilbury in Essex.

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. Known as a ‘slurry’ machine, Mary is specially equipped to deal with the chalk, flint and wet ground conditions that she will encounter in southeast London.

TBM 7 will be used on the drive from Pudding Mill Lane to Stepney Green, which will start in the summer. This is an Earth Pressure Balanced machine designed for the London clay found north of the River.

All the machines’ components are expected to arrive at Crossrail’s sites within the next month where they will be reassembled. There are no manufacturers of tunnel boring machines in the UK.

Andy Mitchell, Crossrail Programme Director said: “Over 4km 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, TBM8, will complete factory testing this summer.

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For further information contact the Crossrail Press Office on 020 3229 9552 or email [email protected]

Notes to editor

The naming arrangements for TBM7 and TBM8 will be advised at a later date.

  • Mary is named after the wife of the famous railway engineer Isambard Kingdom Brunel.
  • Mary weighs 1,000 tonnes and is 110 metres long. TBM 7 is 150 metres long.
  • Each tunnel boring machine has 20 person ‘tunnel gangs’ working in shifts - 12 on the tunnelling machine itself and eight working between the rear of the machine to the tunnel entrance.
  • The diameter of their cutter head is 7.1 metres. Once tunnelling is fully up and running the TBMs are scheduled to progress at an average rate of around 100 metres every week.
  • The TBMs have a rotating cutter head at the front, and a series of trailers behind housing all the mechanical and electrical equipment. As the machine advances forwards, precast concrete segments are put in place to form concrete rings to line the tunnels. The segments are positioned with millimetre precision and held in place by hydraulic rams. Once the segments form a complete ring, the structure is extremely strong and stable. In the final stage of the process, adjacent rings are bolted together.

About Crossrail:

The total funding envelope available to deliver Crossrail is £14.8bn.

The Crossrail route will pass through 37 stations and run 118 km (73 miles) from Maidenhead and Heathrow in the west, through new twin-bore 21 km (13 miles) tunnels below central London to Shenfield and Abbey Wood in the east.

When Crossrail opens it will increase London's rail-based transport network capacity by 10%, supporting regeneration and cutting journey times across the city. Crossrail services are due to commence through central London in 2018.

Crossrail is being delivered by Crossrail Limited (CRL). CRL is a wholly owned subsidiary of Transport for London. Crossrail is jointly sponsored by the Department for Transport and Transport for London.