The construction of artificial tunnels to cross lengths of a route in which there is insufficient overburden for bored tunnel advance inevitably involve deep incisions into the slopes to be crossed with consequent problems of safety and environmental impact.
Rocksoil S.p.A. researched and developed the use of special "artificial overburdens" of improved ground created over the crowns of tunnels before excavation. They can then be bore tunnel driven thereby by-passing all the problems connected with traditional methods of constructing artificial tunnels.
This new method has been used for the construction of approximately 1.5 km of tunnels on the new Milan to Naples and Bologna to Florence High Speed railway lines. It was found extremely practical and safe, not to mention economical and environmentally sound.