This paper illustrates the geological-technical problems encountered in the design and construction of the Küchelberg road tunnel, which constitutes the second completion lot of the Merano bypass in the province of Bolzano, and in particular the characteristics of the specifically developed monitoring system. The tunnel layout runs in an urban environment with low overburden for approximately 2 km in two clearly distinct geological conditions that affect approximately 50% of the tunnel: the Merano side (west) in alluvial soils, the Passirio side (east) in rock. The article describes the type of monitoring system, so-called “active or smart” monitoring, which makes it possible to follow the evolution of significant parameters that are indicators of the potential criticality of the excavation activities on the pre-existing ground with timely updates on a informatic platform.

Keywords: tunnel excavation, geotechnical monitoring, blast vibrations, rock impedance, site law.