Halfway there: HS2’s Northolt Tunnel reaches 8.4 miles under west London

The four railway tunnels that make up HS2’s Northolt Tunnel under west London have reached the halfway mark, with the four tunnel boring machines completing 8.4 miles of tunnels.
Tunnel lining segments being delivered to construct the Northolt Tunnel (c) HS2
The tunnel links the HS2 station at Old Oak Common to West Ruislip, where the railway then comes back above ground to pass over the Colne Valley before diving back into tunnels next to the M25 motorway.
The tunnel boring machines (TBMs