
A 271.5‑tonne Herrenknecht Mixshield TBM, Caroline, has started driving a 2.2km electricity cable tunnel with a 4m internal diameter beneath the River Thames in Essex for National Grid’s Grain to Tilbury project, delivered by the Ferrovial BEMO joint venture. The drive will pass through variable Thames estuary ground conditions between 35m‑deep launch and reception shafts of 15m and 12m diameter, with tunnelling continuing into 2026 and overall scheme completion targeted for 2029. The new tunnel will replace the 1969 Thames Cable Tunnel and carry new high‑voltage circuits between Grain and Tilbury substations.




