Abstract: The invention falls within the art field of shields used in the excavation of tunnels for any given utility (rail, road, underground railway, sewers, pipelines, power cables etc.), and of all sizes. The plant disclosed provides a temporary support structure for tunnel walls, entirely self-propelled and extendible along the direction of excavation, the interior of which accommodates equipment used in digging operations and for the removal of spoil; accordingly, the structure acts as a temporary shoring facility during excavation works, moving forward through the bore and carrying within it the complete battery of excavation and auxiliary equipment while enabling installation immediately behind of the permanent pre-cast or cast in-situ tunnel lining.