07/10/2026
Last Monday, Caroline, the Herrenknecht Mixshield, successfully completed its breakthrough ahead of schedule, reaching the end shaft in Gravesend, UK.
The Grain to Tilbury project, lead by National Grid, aims to replace the existing cable tunnel. Caroline excavated and installed segmental lining along 2.2km beneath the River Thames, working in challenging geological conditions including very strong flintstones, water pressures of up to 4,5 bar and high ground permeability.
This successful breakthrough is the result of high-performing machines, the TBM and the VSM (used to build both the start and end shafts in Tilbury), perfectly integrated additional equipment, ensuring smooth and efficient logistics throughout the entire operation, and strong teamwork on site.
The TBM maintained a high advance rate thanks to its high-performance design and the efficiency of its water circulation system, rock crusher, and tooling. Keeping the machine continuously supplied with segments was key to maintaining this efficient pace.
With two rings available on the segment feeder and one ring positioned on the quick unloader, ring assembly could proceed without interruption. The MSV kept the logistics flow moving by transporting a complete ring directly to the TBM and maneuvering precisely thanks to its remote-control system. Its foldable cabin also allowed it to return to the launch shaft while the segment crane refilled the quick unloader, supporting continuous operation.
Meanwhile, on the surface, the separation system reliably and efficiently filtered the fine chalk particles from the slurry, maintaining the throughput required by the TBM and supporting uninterrupted excavation.
And above all, excellent teamwork made it happen! Well-organized logistics and close coordination between all teams on site were essential to achieving this performance with TBM Caroline and Verena, Europe's largest VSM to date.
Congratulations to everyone involved in this achievement! 🎉
Thank you to our customers for their trust BEMO Tunnelling Ferrovial!