Why do we have an exploration and survey program?

The Brenner base tunnel, in its basic form, consists of two main tunnel tubes and an exploratory tunnel lying 12 meters (and just before Fortezza, rising to 10 meters) below the two main tubes. This exploratory tunnel is being excavated for the purposes of geological and hydrogeological prospecting and exploration. This preliminary research will help to minimize construction costs and risks.

The section of the exploratory tunnel running from the Sill gorge near Innsbruck in the Ahrental valley south of Innsbruck to the multifunction area of Innsbruck with the Ahrental lateral access tunnel will be excavated using conventional, cyclical methods. The more southern sections running to the Brenner massif can be mechanically excavated, though the access tunnel of Steinach/Wolf will be excavated conventionally.

The sections south of the Brenner can be excavated partly using machinery and partly by blasting up to the Periadriatic Line. The Periadriatic Line will be crossed using cyclical excavation and the same method will be used for the access tunnel near Mules. The section of the exploratory tunnel from Aica to Mules will be excavated mechanically.

The exploratory tunnel will allow deep prospecting appraisals (preliminary boring, boreholes running perpendicularly to the tunnel axis, deformation measurements etc.) that are only with difficulty or absolutely not feasible from the surface. The construction program was therefore drawn up with an investment volume of 430 million Euro.