The planned road runs along the western side of Lake Como, in one of the most renowned Larian tourist areas, for a total length of almost 10 kilometers, in the section between the municipalities of Colonno, to the south, and Griante, to the north, also affecting the territories of Sala Comacina, Ossuccio, Lenna, Mezzegra, Azzano and Tremezzina.
The project involves the construction of a roadway with one lane in each direction for an overall width of the roadbed of 9.50 meters.
To the south, the intervention includes the deviation of traffic at the height of Colonno, with a tunnel entry, with return to the coastal road near Griante. The new route includes four main tunnels (totaling about 8.3 km) and a crossing of the incision at the Perlana stream by viaduct. The three longer tunnels have a safety tunnel placed upstream, parallel to the main axis. For the first two, the safety tunnel will be constructed by mechanized excavation method using a double shield TBM (diameter 7.55 m)
The road system also includes two interchanges at the beginning and end of the lot, useful for temporary management of the road system. Said works will then be maintained in the final configuration.
Indeed, one of the major design challenges is the particularly complex logistical and construction site environment. The construction site areas, consisting of narrow strips located between the mountain slope and the lake, make it necessary to meticulously organize the execution phases, the coatings between the various work teams, the management of spaces for the storage of materials and in the movement of construction vehicles to allow proper access to all areas.
One of the main issues faced during the design activity of the intervention was the management of spoil from the excavation operations of the natural tunnels.
In particular, due to the distance of suitable disposal sites in the northern area of Lake Como, as well as the further increase in vehicular traffic on the state highway with the construction site traffic, it was decided to transport most of the spoil by lake. Therefore, it was planned to build two docks, made with temporary structures used as piers, to allow the relevant loading and unloading operations, through the use of motorized floating barges.