The work and the technique: The Sfalassà and Favazzina Bridges, Italy
The construction project of the new Salerno-Reggio Calabria highway includes two works of great engineering interest: the renovation of the Sfalassà Viaduct and the construction of the new Favazzina Viaduct.
The first Sfalassà viaduct built by Impremaviter S.p.A., later merged into the Webuild Group, and inaugurated in 1972, featured a mixed steel and reinforced concrete structure that was particularly innovative. And so much so, that it won the European Convention of Metal Construction award for the three-year period 1970-1972.
The viaduct is suspended 249 meters above the stream that runs at the bottom of the valley, making it the second highest viaduct in Italy. The solution that allowed for a single leap over the deepest part of the gorge is a mixed structure consisting of pre-stressed concrete access decks from which the central overpass, consisting of a single metal gantry span, with sloping piers, with a span of 376 meters, departs.
Between 2008 and 2012, the viaduct was completely renovated and partly reconstructed by the Webuild Group. The engineering challenge was to work in an extremely steep valley with a valley floor that did not have a suitable geological structure to support the supporting structures, in addition to the entire area being subject to high seismic risk.
The very high environmental constraints also required the removal of all old materials and the re-environmentalization of the slopes, where trees and natural vegetation were replanted.
In contrast, the new Favazzina Viaduct was opened on March 4, 2013, and is the flagship of the highway connecting the South with the rest of Italy. Its reconstruction was a key step in the work to modernize the Salerno-Reggio Calabria highway The new Favazzina - like the original viaduct - inserts itself into the mountains within two tunnels, the Brancato on the Reggio Calabria side, and the Muro on the Salerno side, with a curvilinear layout from start to finish.
It has a total length of 440 meters, divided into a central span of 220 meters and two side spans of 110 meters. The deck is made of a mixed steel and concrete system and is supported in the void by huge piers, which are firmly planted in the valley. Stack 2 of the south roadway, the smallest of all, is 54.6 meters high. A height that reaches 91.9 meters for stack 2 of the North roadway.
Favazzina is suspended in the middle of a deep valley surrounded by steep mountains, and both sides have slopes exceeding 65°. For these reasons, stricter safety measures were taken in the construction of the bridge than what is required by law. The guardrails on the worktops were raised up to five feet, and a fall prevention net was placed along the entire length of the work to mitigate the view and minimize the risk of panic.