Upgrading works of the A1 Motorway Appenines mountains crossing between Sasso Marconi and Barberino Del Mugello, lot 2. For approximately 3 km the works involve the strengthening of the existing structure (mainly construction of the 3rd lane), while the remaining part is a modification of the original motorway route. Between kilometres 206+444 and 209+600, the alignment of the motorway deviates from the existing one and includes a tunnel stretch and the construction of a new viaduct over river Reno. The construction of Sasso Marconi interchange and pay toll station and two variant roads completes the works. The underground stretch consists of a three lanes twin-tube tunnel. The tunnels length is 2,266 m for the north drive and 2,209 m for the south one. The design of the tunnel foresees three lanes for each drive; the excavation section is 130 m2.