WP112.1 Permanent Walkways

The works are located at Northolt Tunnels West (NTW) Northolt Tunnels East (NTE) and Euston Tunnels (ET). At each location a twin-bore tunnel will be constructed, forming two parallel tunnels, each containing a single rail track. SCS JV will construct 13 miles of twin-bore tunnels on the HS2 route using six TBMs, of which five will operate simultaneously.

Approximately 42km of escape and maintenance walkway must be constructed throughout the length of the running tunnels. The emergency walkway shall run on the cross passage side and connect to it as well as to safe areas at portals, intervention points and shafts to provide a safe walking route. The maintenance walkway shall be installed on the opposite side to facilitate access for the inspection, maintenance and periodic component replacement operations necessary for train operation.

The preferred construction methods for the tunnel walkways shall be either horizontal slip-forming system (slip-forming paver) or a system using mechanised shutter-based slip formwork.