By rosebell
Tunnelling for National Grid’s new power tunnel under the River Thames has reached the halfway point.
Ferrovial BEMO JV has completed more than 1.1km of the 2.2km drive from Essex to Kent and installed 840 rings.
TBM Caroline – a Herrenknecht mixshield machine – has excavated more than 19,000m3 and is progressing at more than 24m a day.
The high-voltage tunnel, which lies 35m underground, will replace the existing Thames Cable Tunnel constructed in the 1960s. The project is part of National Grid’s Great Grid Upgrade to future-proof the UK’s electricity transmission network.
TBM Caroline began her journey in May from the 48m-deep launch shaft in Tilbury. The 15m-diameter launch shaft, and the retrieval shaft at Gravesend, were built using Europe’s largest vertical shaft sinking machine, manufactured by Herrenknecht.
