Meet our giant Tunnel Boring Machines
How does it work?
- a rotating cutterhead
- a screw conveyor
- conveyor belts or extraction pipes
- a tunnel segment erecto
Building the HS2 tunnels
We will use TBMs to excavate tunnels through a variety of soil and rock in dense urban areas and to reduce environmental impacts in rural areas.
In total 10 giant TBMs will excavate new tunnels on the first phase of the high speed railway between London and the West Midlands.
Each machine operates as a self-contained underground factory, which as well as digging the tunnel, will also line it with concrete wall segments and grout them into place as it moves forward at a speed of around 15 metres a day. A crew of 17 people will operate each TBM, working in shifts to keep the machines running 24/7. They will be supported by people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation.
Boring statistics – HS2 tunnelling in numbers
- HS2 will use ten giant tunnelling machines to construct new high speed rail tunnels for the London to West Midlands (Phase One) section of the route.
- The TBMs are up to 170m in length – nearly 1.5 times the length of a football pitch.
- Each one weighs roughly 2000 tonnes – the equivalent of 340 African bush elephants.
- The HS2 tunnels will go as deep as 90 metres (m) below the ground – ensuring communities and countryside above are not impacted by the railway.
- The size of the largest HS2 TBM cutterhead is 10.26m, roughly the height of two giraffes standing on top of one another.
- The internal diameter of the tunnels in which the trains will pass through will be around 9m, slightly larger than two London buses stacked on top of one another.
- The tunnels will be lined with concrete segments that will be 2m x 4m and weigh on average 8.5 tonnes each.