A new milestone has been surpassed as another HS2 Tunnel Boring Machine (TBM) has completed its five-mile journey beneath London.
The TBM, nicknamed Sushila, completed its two-year journey to reach the Green Park Way vent shaft in Ealing on 19 December with the aid of an innovative method utilising high water pressure in the ground on site.
The method allows the TBM to maintain pressure while sealant is applied from the tunnel lining in order to prevent water ingress, with the TBM set to be removed once the area has been depressurised.
“This is our first breakthrough for the Northolt Tunnel and is the result of many years of hard work from our tunnelling contractor.
“We are on schedule to complete our first tunnel for HS2 trains under the capital by the end of 2025, just as we prepare to bring HS2 tunnels into the heart of the London at Euston.”
Sushila is the first of four separate boring machines tasked with the completion of the 8.4-mile Northolt tunnel that will carry high-speed trains between HS2’s main station at Old Oak Common, West London, and the outskirts at West Ruislip.
Each TBM, created by Herrenknecht AG, is set to complete its journey at Green Park Way, with each arriving in both a main and satellite shaft having travelled at an average speed of roughly 16 metres per day.
Construction of the Northolt Tunnel has thus far been handled by a joint venture of companies Skanska, Costain and STRABAG (SCS), with the same companies also tasked with the construction of HS2’s Euston Tunnel eastward.
“The arrival of Sushila at the Green Park Way ventilation shaft marks a huge step in the delivery of the Northolt Tunnel and the new railway. This achievement reflects the tremendous efforts of the entire team, which has drawn together global capability to deliver this incredibly complex section of work.
“We are making great progress on the remaining tunnelling, with three further TBMs in operation on the Northolt Tunnel and the two Euston Tunnel TBMs currently being prepared for launch.”
