The mechanical excavation of the exploratory tunnel in Aica, which is about 10.500 meters long, began o April 28th 2008. Work is progressing apace.

The tunnel boring machine (TBM) was started up and the construction site was inaugurated with a special ceremony in the presence of the President of Italy, Mr. Giorgio Napolitano.

At the end of June 2009 about 5.438 meters had been excavated.

The exploratory tunnel has an average cross-section of 31.15 m2 and is being excavated through Brixner granite.

The first 150 meters of the exploratory tunnel running from Aica northwards to the access tunnel of Mules were excavated by blasting.

The TBM is 134 meters long (12 meters for the body of the machine and 122 meters for the so-called back-up), has a shield with a 6.3 meter diameter and weighs 550 tons. With this type of TBM tubbing rings are built in as a preliminary stabilization measure.

The excavation push exerted on the drilling head by the 14 pistons moving the front shield can reach a total theoretical pressure of 25.000 kilonewtons. Cylinders press against the grippers‘ back shield. The excavated area is stabilized by installing tubbing rings. The back part of the shield has 19 hydraulic pistons which push the TBM forward with a total capacity of 34.400 kilonewtons.
A 400 meter long connecting tunnel is also being built from the construction site between the Unterplattner and Hinterrigger areas. This tunnel, which was blasted, was finished on June 10th, 2008. It is used to carry away the spoil: a conveyor belt that is over 1.000 meters long moves the spoil from the tunnel in Aica through the connecting tunnel to the Hinterrigger disposal site.

Status: July 2nd, 2009