Contractor, Tunnel Zürich-Thalwill consortium, broke through on May 7 the final 2.7km long drive (Lot 2.01) of the 9.4km long, $118M Zürich-Thalwil tunnel in Switzerland.
The JV started boring on 31 March 1999 using a 12.3m diameter Herrenknecht mixshield TBM. The machine bored through mostly good ground in open mode for the first 1.9km but switched to closed mode for the 700m final section of river and lake deposits underlying the lower urban reaches of the city. The tunnel crown ranges in depth from 5m to 12m.
The other major tunnelling contract on the project is 3.01. A hard rock shield Herrenknecht TBM completed the 5.7km long drive in December last year.
The Zurich-Thalwil tunnel will become a part of Switzerland’s $5bn Bahn 2000 programme being constructed for the SBB railway authority.
