First mile of West London’s HS2 tunnels completed, but Government report raises concerns

The first mile of the two HS2 tunnels running under west London from Ruislip towards Old Oak Common has been completed, and is on target for the tunnels to be completed by 2025.
The Northolt Tunnel (c) HS2
The HS2 railway runs in tunnels from Euston to the station at Old Oak Common, and then in tunnels roughly parallel with the Central line up to Ruislip, where the trains will then run over the lakes on a long viaduct before ducking back down into tunnels under the Chiltern hills.
Known as the N