Underground engineering

Alternative route of Imperia

Works on the S.S.1 ‘Aurelia’ in the municipalities of Imperia and Diano Marina
Owner/client ANAS S.p.A.
Type of service Final Design for Integrated Agreement; Environmental Impact Study
Location Province of Imperia
Period 2010 - 2012
Cost € 413.000.000

PRO ITER Prog. Infrastr. Terr. (51%); SO.TEC.; ProGei; Giugiaro Architecture

Thanks to the new route it will be possible to decongest traffic in the town of Imperia and in particular in a very critical area where the new (and sole) railway station of Imperia is being constructed.

This alternative ordinary road will prevent medium and long distance traffic from transiting in the town center. A fast connection to the main roads and the most relevant urban and suburban areas shall also be ensured. In addition, this road will join the existing road network by means of junctions located in places where traffic flows are very high.

The route, approx. 10 km long, involves the municipalities of Imperia, Diano Castello and Diano Marina. In the municipality of Imperia it develops from the Imperia West exit of the 'Autostrada dei Fiori' motorway to the Imperia Est exit, both in tunnels and viaducts. At Imperia Est the route continues in tunnels as far as the San Leonardo mountain from where, in viaducts and parallel to the motorway, it enters the municipality of Diano. The territory of Diano Castello is crossed for a short stretch in the final part of the route.


8 natural tunnels (total length: 7.24 km).

Viaducts & Bridges

4 viaducts passing through valleys.

Road junctions

9 road junctions with roundabouts at single level.

The various difficulties, both constructive and architectural-environmental, due to the several restraints posed by a heavily built-up territory, have been solved thanks to integrated solutions adapted to the orographic and landscape context of the surrounding environment. The definition of the works of art has been strongly influenced by the importance of the territorial context reflected in the choice of valuable constructions, in particular in the most sensitive areas. The viaduct structure ranges from mixed two-beam decks made of steel/concrete to half-through arch bridges. The tunnel entrances, located in small narrow valleys, consist of reduced length portals with continuation walls lined with natural stone.

The design of the underground focusses on the aspects of user safety in case of emergency (specific plants and structures, including the presence of an escape pedestrian gallery under the road surface).

The work, due to the very nature of the areas involved, poses mainly environmental problems; although 70% of the route develops in tunnels, environmental compensations and mitigations are an issue in the open-air stretches in small valleys or heavily built-up areas.

The various problems, both of constructive and architectural-environmental nature, determined by the many and varied constraints on a highly built-up area, have been resolved by addressing integrated solutions and adapted to the orographic and landscape context of the surrounding environment.