The High Speed Railway Project, aiming at quadrupling the most congested railway lines, is based on the high technology and represents a strengthening of the existing railway network.

The Bologna to Florence line represents a strategic line of the domestic railway network and collects a great number of difficulties in a few tens of kilometres.

The geomorphologic complexity of the ground to be crossed, together with the presence of gases and of considerable quantities of water emphasized important engineering problems, being the line carried out mainly underground.

The total length of the line (km 4+884 ÷ km 83+366) is 78.482 meters, 71.831 meters of which of main tunnels (no. 9), 1.177 meters of bridges and viaducts (no. 11) and 5.474 meters of railway embankments.

Furthermore access tunnels for a total length of 8.869 meters and service tunnels (1.350 meters excavated using conventional methods and 9.259 meters using a tunnel boring machine) have been excavated in addition to the main tunnel.

Tunnels, excavated using conventional method, have a polycentric section with a crown radius equal to 5,75 meters.

The internal section is 82 m2, excavation radius varying from 6,40 to 7,00 meters.