The work and the technique: Fortore Tunnel, Italy

For the construction of the Fortore Tunnel, the company Girola—later merged into the Webuild Group—was entrusted with building approximately 6,600 meters of tunnel, over 250 meters of access window, and a 235-meter canal bridge crossing the Sente stream valley and connecting two tunnel sections.

Works were financed by Cassa per il Mezzogiorno and were particularly complex due to the tunnel’s terrain composition. For this reason, the mechanized shield technique was used. It enabled supporting the excavation front through special swinging pistons.

The shield that was designed and built in the Girola workshops, differently from others, was made from a metallic structure that reproduced, with an external metal sheeting, the whole excavation profile allowing to support the terrain, and to work safely with the same principle still used today for the traditional excavation techniques.
The regular progression and the eventual presence of firedamp gas were both factors that were constantly monitored.

Concrete jet operations for the final covering of the tunnel were carried out by using metal telescopic formworks that were transported by a special rail wagon. 

Works were organized in detail to reduce inactivity to the minimum; rail tracks were progressively added, and switches for the small railway that moved the waste material produced from the excavation sites towards the discharge point, helping transport activities in both directions. A wagon overturning system with a hydraulic piston that allowed a single worker to carry out these operations were also put in place.