ASSEMBLY OF the first tunnel boring machine for the Gotthard Base Tunnel on Switzerland's AlpTransit project is due to start at the south portal at Bodio this month.
In November, the 410m long, 8.83m diameter, 3,050t Herrenknecht Gripper TBM will begin excavating the 30km long east tunnel of the 57km long twin bore scheme through hard gneiss bedrock between Bodio and the Faido crossover station (see p21 this month). At Faido the cutter head will be enlarged to 9.40m and the TBM will continue on to the Sedrun portal.
Tunnel AlpTransit-Ticino (TAT) - a joint venture of Swiss contractors Zschokke Locher and CSC Impresa Costruzioni, Alpine Mayreder Bau of Austria, Impregilo of Italy and German firm Hochtief - is building the Bodio-Faido section for client AlpTransit Gotthard.
Developed with TAT, the cutter head and the rock support equipment including anchor drilling, probe drilling and shotcrete robots are all based on Herrenknecht's experience of hard rock technology.
The second TBM for the western tube of the Bodio-Faido section is now being finished at the Herrenknecht's factory in Schwanau, southern Germany.