Tunnel boring machines Crossrail will use eight tunnel boring machines to aid construction of the rail tunnels. These huge machines will work 24 hours a day beneath the streets of London, excavating large volumes of ground and erecting the concrete tunnel lining

Tunnelling

The Crossrail route links the new stations at Paddington, Bond Street, Tottenham Court Road, Farringdon, Liverpool Street and Whitechapel. The railway divides at Stepney Green, with the southeast spur running underground to Plumstead and then onto Abbey Wood via the Isle of Dogs and the north east spur running underground to Pudding Mill and then onto Shenfield in Essex. All of this adds up to 42km of bored tunnels located below the busy streets of London

The tunnels will weave their way between existing underground lines, sewers, tunnels and building foundations from station to station at depths of up to 36m.

Two different techniques will be used for the tunnel construction;

  • Tunnel Boring Machines will be used to build 6m diameter tunnels for the trains to travel between stations
  • Sprayed Concrete Lining will be used to build the larger platform tunnels at stations and the shorter passenger circulation tunnels at stations

A number of tunnel drives are planned to construct the Crossrail tunnels using tunnel boring machines (TBMs)

The tunnels will be twin bore, running from;

  • Royal Oak to Farringdon (6.2km)
  • Limmo Peninsula to Farringdon (8.3km)
  • Stepney Green to Pudding Mill (2.7km)
  • Limmo Peninsula to Victoria Dock (1.0km)
  • Plumstead to North Woolwich (2.6km)

The type of TBM will be chosen to suit the respective ground conditions. Generally it is anticipated earth pressure balance machines will be used, except for the drive from Plumstead to North Woolwich where a slurry machine is probable.

Ongoing review and refinement of the tunnelling strategy and the future railway operation has resulted in the omission of a tunnelling site at Hanbury Street, near Spitalfields Market in East London and the further removal of a number of other shafts.

It is estimated that 8M.m3 is expected to be generated by the tunnelling work and excavation of stations and ticket halls. Tunnelling works will produce a significant proportion of this material which will require removal from the works.

A great deal of attention has been given to this issue. Where practical the material will be moved along the tunnels to the sites at Westbourne Park near Paddington and Limmo Peninsula near Canning Town, to reduce the need for lorry movements in Central London.

Tunnelling Academy

Crossrail is building a Tunnelling Academy to address the shortage of people with the necessary skills to work on the project. The Crossrail Tunnelling Academy will be a purpose-built facility providing training on the key skills required to work in and around a tunnel excavation and build environment. It will ensure that all personnel working underground on the project achieve the Crossrail safety card before working on any Crossrail site.

The proposed site for the Academy is in Newham. Some classroom-based courses will be available in late spring 2010, with the Academy fully open by October 2010.

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