High Speed Two (HS2) has rolled out the fifth tunnel boring machine (TBM), known as Caroline ,  for the construction of tunnels for the railway through London.

Caroline, which is the second TBM in London, will work along with Sushila TBM on the West London site.

The giant tunnel will excavate for 22 months towards Greenpark way in Greenford. It will be used for boring five miles of the twin-bore Northolt Tunnel.

With an ability to travel at an average of 14m a day, Caroline will excavate the five-mile tunnel and equip 4,207 tunnel segment rings to form the tunnel.

Each ring of the tunnel is covered by seven concrete segments, which were produced by Pacadar in the UK.

HS2’s main works civils contractor Skanska Costain STRABAG JV (SCS JV) will operate the giant machine. The JV is engaged in the construction of HS2 tunnels in London.

To build an additional 3.4-mile twin-bore tunnel, two other equally massive tunnel boring machines will be deployed towards Greenpark Way from HS2’s Victoria Road site next year.

The quartet of TBMs will construct 8.4 miles of twin bored tunnels between West Ruislip and the new high-speed rail super hub station at Old Oak Common.  

HS2 civils delivery director Mike Lyons said: “HS2’s construction continues to gather pace, and the launch of the fifth Tunnel Boring Machine on HS2 is another significant moment for Britain’s number one levelling-up project.

“Creating jobs and contracts for businesses today, HS2 is an investment in Britain’s economic growth now and for generations of rail passengers to come.”