Modernisation works of SS 42 “del Tonale e della Mendola” – East bypass of Edolo (BS) – Lot II.

Project objective

The intervention is among the infrastructure works connected with and contextual to the so‑called Milan–Cortina 2026 Olympics Decree, and consists of a variant of SS 42 which currently crosses the built‑up area of Edolo and connects the Alta Valle Camonica area to Bergamo towards SW and to Bolzano towards NE, designed adopting a “C1” road cross‑section.

Main works of competence

South open‑cut section
Starting from the South roundabout (R = 23.0 m), the alignment develops for a long stretch first in open cut (150 m) and then in an artificial tunnel (340 m), largely alongside the ENEL power plant, up to the connection section with the natural tunnel.

Natural tunnel
Excavated using “traditional” methodology, featuring a monocentric internal profile with circular cylindrical vault (internal radius 6.45 m). Total length 1,443.79 m with maximum longitudinal gradient 6.05%.
Single tube with two‑way traffic; as its length exceeds 1,000 m, the tunnel is equipped with a safety adit located below the carriageway, with escape routes (accesses to the adit) every 300 m at the lay‑bys and two final exits near both the South and North portals.

North open‑cut section
The artificial tunnel section has a limited extension (23 m), with portal shaped as an “inverted flute‑beak”, and leads to the new bridge and the North roundabout (R = 17.0 m).

Oglio River bridge
Single span, straight axis, simply supported, with design span (distance between supports) 60.00 m. The deck consists of a steel structure made of a grillage of longitudinal and transverse beams with a reinforced‑concrete slab cast on top.
The structural type is a “tied arch” bridge: the deck is supported by hangers (“pendini”) suspended from two upper circular steel arches.