The TBM has broken through on the Thalwil flood relief tunnel in Zurich.
Operated by Marti Tunnel AG, TBM Delia was launched seven months ago to excavate the 2km-long tunnel from the Sihl Valley to Thalwil.
The 6.6m-diameter tunnel will protect the city of Zurich and the lower Sihl valley from flooding by diverting the River Sihl into Lake Zurich during heavy rain.
