The project envisages the adaptation to four lanes of the Strada di Grande Comunicazione SGC E 78 Fano-Grosseto in the stretch between Grosseto and Siena from km 30+040 to km 41+600.

The morphological characteristics of the road require numerous works, including 9 viaducts.

The two bridges over the Farma River are the most important bridge works, with a total length of 792 and 903 m. The piles reach heights of about 100 m with, with spans 57 m long. The new viaduct provides a central span of 114 m, over the Farma River bed
3 tunnels are provided along the stretch, 2 of which coupled to the existing tunnels. The longest tunnel is Casal dei Pari, with length of about 1,500 m.

There are 9 artificial tunnels acting as rockfall protection, to reduce the visual impact of the new section, altogether with 5 junctions connecting to the existing road network.