A major milestone in the construction of the High Speed 2 (HS2) railway was reached on Saturday, March 15, 2025, as TBM Sushila’s cutterhead, front, and middle shield were lifted from a vent shaft in a single operation. Weighing 850 tonnes, the components were extracted using a powerful 750-tonne gantry crane, marking the conclusion of the tunnel boring machine’s role in the Northolt Tunnel project.
TBM Sushila, manufactured by Herrenknecht AG, was deployed as one of four tunnel boring machines deployed for the Northolt Tunnel, was launched from West Ruislip in October 2022. Over the course of its journey, it excavated more than 1.2 million tonnes of earth and installed 4,217 tunnel rings. It successfully completed its 5-mile (8.4 km) tunneling operation in December 2024. This tunnel will allow HS2 trains to travel between Old Oak Common Station in London and the outskirts of the capital, playing a key role in the high-speed railway’s connection between London and Birmingham.
The extraction process was a complex engineering feat, requiring meticulous planning and execution. The use of a 750-tonne gantry crane ensured the safe removal of the massive components, an essential step in clearing the tunnel for the next phases of the HS2 project. Images of the operation, released by HS2 Ltd., highlight the scale and precision involved in handling such large machinery.
The Northolt Tunnel forms part of HS2’s Phase One, which aims to improve rail connectivity and reduce journey times between major cities in the UK. The project utilizes advanced tunneling techniques to minimize environmental and community disruption while ensuring efficient construction progress.
With TBM Sushila now successfully removed, attention shifts to completing the remaining sections of the Northolt Tunnel and advancing HS2 toward its ultimate goal of transforming the UK’s railway network. The completion of this tunneling phase represents another step forward in the realization of one of Europe’s largest infrastructure projects.
