20 December 2021

Fereggiano hydraulic bypass in Genova

Genoa is frequently hit by disastrous floods; therefore, the Municipality has recently carried out part of the works included in the Definitive Project of the Bisagno river deviation tunnel. Wednesday 17.02.2016 the Minister of the Environment declared: "In Genoa we are carrying out one of the most important hydrogeological remediation interventions ever carried out in Italy". The project, relating to the first contract, is called the Deviation of the Fereggiano River: a 3.7 km long and 6 m wide tunnel that runs from the mouth of the river, north of the city, on the east coast, under some of the densest neighborhoods populated in the city. The main object of the contract is the excavation under the low-coverage city, the two main construction sites on the most populated coast of the city and in the narrow riverbed of the Fereggiano, the secondary construction sites are inside the city.

The Fereggiano Tunnel is a horseshoe-shaped tunnel 5.2 m wide and 3.723 m long, with a longitudinal slope of 0.3%. The first 909 m were excavated with an open TBM in the early 1990s and were safeguarded with a concrete lining casting. The section of this first section is narrower than the new Fereggiano Tunnel and with a free carriageway of 2.75 m it is one of the main logistical nodes of the work.

The Fereggiano Tunnel begins with the outlet to the sea on the "Corso Italia Mare", one of the most beautiful walks in the region, and then passes mainly under the "Albaro" quarter, with a variable coverage between 35 m and 160 m, and ends under the river-bed of the Fereggiano river with a 22 m deep intake shaft. The main task of this work is not only to dig the tunnel, long and complicated with a rather narrow section and several other engineering tasks, but above all to cope with the delicate urban environment.