Road network upgrade between the Uzzone–Belbo Valleys and Alba.

Project objective

The objective of the study is to identify possible road corridors connecting to the Alba area, aimed at reducing the infrastructural, tourism and commercial isolation of the Belbo, Bormida di Millesimo and Uzzone valleys, while also enhancing the respective territories.

Interventions – summary description of the alignments

T “A1” – Bosia ↔ Cortemilia (Uzzone–Belbo connection)
Directly connects SP439 (Cortemilia) to SP31 (Bosia) via an approximately 2.64 km tunnel with roundabouts at both ends; it is the complementary work linking Valle Uzzone/Liguria and Valle Belbo, supporting all alternatives.
T “B1” – Bosia → Ponte Mabuc
Starts from SP31 (Bosia), crosses the Belbo via a viaduct and the Bosco della Foca ridge in tunnel, reaches the intermediate connection on SP281 and continues underground towards Villaro–Manera up to the junction with SP429 just downstream of Ponte Mabuc. Length 6.74 km.
Main works: 1 initial tunnel 1.660 m, 2 viaducts (354 m, 115 m), 2 final tunnels (2.200 m, 1.190 m) and 1 viaduct 200 m.
T “B2” – Variant of the B1 terminal section
Follows B1 up to SP281; in the final section it deviates westward to bypass Bric del Vallone and ties into SP429 at the Cherasca stream, downstream of the B1 roundabout. Length 8.03 km.
Main works (final variant): 3 terminal tunnels (1.990 m, 940 m, 1.010 m) and 1 viaduct 160 m; initial portals unchanged (tunnel 1.660 m; viaducts 354 m, 115 m).
T “B3a” – Campetto (SP592) → Ponte Mabuc
Origin at Campetto with a roundabout on SP592, viaduct over the Belbo, tunnel at Bric Rama; it runs along the Rio Berria valley with viaduct/cut sections up to the roundabout on SP281; it then continues as B1 towards Villaro–Manera and ties into SP429. Length 6.68 km.
Main works – initial section variant: tunnel 780 m; 4 viaducts 230–200–120–115 m; plus 2 terminal tunnels (2.200 m, 1.190 m) and terminal viaduct 200 m.
T “B3b” – Campetto (SP592) → Ponte Mabuc
As per B3a at the origin, but with a longer Bric Rama tunnel underground (1000 m): outlet into the Rio Villa valley, crossing Rio Villa and Berria before rejoining SP281 (roundabout) and continuing as B1. Length 6.67 km.
T “B4” – Initial variant of B1
Shares the origin on SP31 and the tunnel under Bosco della Foca; it emerges earlier into the Rio Berria valley and runs along the right-hand slope with bridges/viaducts and cut/fill sections, reconnecting to B1 shortly before the roundabout on SP281; then as B1 up to SP429. Length 6.86 km.
Main works (initial variant): tunnel 880 m; 3 viaducts (354 m, 110 m, 115 m).
Nodes and overall consistency
The main junctions (SP31/592/429 and SP281) are resolved with roundabouts, with minor adjustments to the access arms and a short embankment realignment near the SP281 plateau; overall, all alignments provide a faster and safer itinerary compared with the current SP429.