Work on the NRLA begins at the Gotthard on 4 October 1993, with the groundbreaking ceremony for the Piora exploratory boring system. Construction of the Kandersteg exploratory tunnel begins at the Lötschberg in spring 1994. Geological surveys are carried out at both locations to identify the most favourable route for the line. The construction projects are drawn up on the basis of this data, along with rail technology and political requirements.
« The reliability of the geological and geotechnical forecast based on an exploratory bore is restricted by the bore itself. »T. R. Schneider, Geological and geotechnical project groundwork from the exploratory Piora Basin bore, p. 15, 31.08.1991