The Direct Pipe technique has been used for this work due to the need of overcrossing a protected area, where the Ministry of Environment had imposed the constraint of using a trenchless technology.
The Direct Pipe allowed to cross a total length of approximately 1.420 m. Works were carried out in two sections starting from the two ends. The TBM was then recovered in the middle of the route, and the two sections were then connected.
It was the first project in Italy and in Europe using large diameter Direct Pipe technology, namely 56”. The works were executed in very difficult soil conditions due to the presence of coarse gravel lenses. However, a high laying precision at the arrival points was ensured, which was required for the subsequent connection of the two pipe sections.
The geometrical characteristics were L= 685 m and vertical curve Rv= 2.500 m for the “Cave Danesi A”, while for L= 770 m and vertical curve R= 5.000 m for the “Cave Danesi B”.