Traversing of the Piora Basin is completed on 15 October 2008 in the east bore - a milestone for the Gotthard Base Tunnel. The basin had been much talked about, not just among geologists and engineers but also the general public and parliament. The sugar-grain dolomite, which was subject to high water pressure, threatened to endanger construction of the entire tunnel. During the planning phase, the Piora Basin had been investigated by means of an exploratory bore comprising a 5.5-kilometre tunnel.
« The water pressure measured in the tunnel equates to the difference between the hydraulic potential and the topographical height of the tunnel. »Federal Institute of Technology Zurich, Geothermic investigations of the Piora Basin, p. 15, 01.06.1997