ABSTRACT
This paper describes the main aspects of the Detailed Design of a number of road tunnels to be built as part of this motorway bypass, which lies just north of Genoa in Italy. In association with a complementary project west of the Polcevera River, this project consists of connecting the three A7, A10, and A12 motorways. This will significantly improve vehicular circulation whilst also reducing urban and local traffic. The works consist of twelve tunnels to be excavated using the conventional method, a number of bypasses, and a mechanised safety tunnel. The Detailed Design updates and extends the Preliminary Project (2011) and incorporates the new geotechnical information that became available as a result of additional ground investigations. This paper provides an overview of the different methods of advancement proposed for the underground works in relation to the different layouts, which include tunnels whose internal cross-sections are designed to accommodate from 1 to 4 lanes; a specific description is also given of the deep and large-face tunnelling works. Following a general description of the geomechanical formations encountered and traversed is a section highlighting the issues that make work of this type so important for excavation, ground support, and the structural solutions adopted, as well as for managing multiple tunnelling works that are carried out simultaneously on one site.
