The key tunnel link was achieved at the Carnwath Road Riverside site in Fulham with the breakthrough of the West main tunnel connection into the Central section.
A special 75m connection tunnel has been constructed to join these two sections. Originally the plan was for TBM Millicent to break through into the shaft at Carnwath Road.
But this was deemed to be too disruptive to the TBM Rachel drive so the decision was taken to turn and bury TBM Millicent before the final shaft and dig the final connecting section.
The final connection between the sprayed concrete lined tunnel and the segmental tunnel involved the West section team carefully breaking out the precast tunnel segments and forming an enlargement around the segmental interface ring.
Prior to the works starting the team carried out a full scale trial of the connection to ensure that the they could achieve the quality required.
Works on the connection tunnel started in January this year and have now achieved the breakthrough.
Now 20km of the 25-km ‘super sewer’ have been constructed with secondary lining underway.
TBM Selina is tunnelling the final section from Chambers Wharf in Bermondsey to Abbey Mills Pumping Station.