Widening of the 800m deep Sedrun II shaft on the Gotthard tunnel got under way last month, after the 1.8m diameter pilot hole was completed with zero deviation.
South African RUC Mining Contractors is widening the shaft to 7m using a Wirth VSB VI. A Wirth raise-borer was used to bore the pilot hole.
The Sedrun II shaft is primarily a ventilation shaft, but will be used for service access and rescue before and after completion. It forms part of the Sedrun intermediate stage, a 6.2km long section of the Gotthard rail tunnel in Switzerland, which will have a completed length of 57km.
The Sedrun section is the most complex of the whole project as it involves penetrating the northern part of the Tavetsch intermediate massif.
