The tunnel boring machine (TBM) that will excavate National Grid’s Thames Cable Tunnel has successfully passed its factory acceptance test (FAT) at Herrenknecht AG’s manufacturing facility in Schwanau, Germany.

The mixshield TBM will be deployed by the Ferrovial BEMO Tunnelling joint venture to construct the 2.2km-long tunnel beneath the River Thames. The new tunnel will replace an existing electricity cable tunnel originally built in the 1960s, forming a key part of National Grid’s infrastructure upgrade programme.

According to Herrenknecht AG, the TBM has been designed to operate in demanding geological conditions, including very strong flintstones, high ground permeability and water pressures of up to 4.5 bar. The successful completion of the FAT confirms the machine’s readiness for these challenging conditions.

The TBM will be launched using a complex umbilical system and will connect two deep shafts constructed with the largest vertical shaft sinking machine (VSM) ever produced by Herrenknecht AG in Germany. The VSM, with an internal diameter of 15m, is being used to sink both the launch and reception shafts for the project.

Tunnelling will begin from the launch shaft at Tilbury, at a depth exceeding 45m below ground level. The TBM will then advance beneath the River Thames towards Gravesend, where it will arrive at a similar depth of approximately 45m.

The successful FAT marks a significant milestone for the Thames Cable Tunnel project ahead of the TBM’s delivery to site and the start of tunnelling operations. For further information please click here. 03/26.