Currently, a busy section of the A1 highway in Italy between Bologna and Florence is being extended as part of the Variante di Valico extension project. In the future, this section will accommodate at least three traffic lanes on both sides.

The new alternate route includes the construction of the Sparvo Tunnel, the profile of which will set a new record in mechanised tunnelling as far as the drilling diameter is concerned. The tunnel will consist of two parallel-running tubes with a length of 2.5 km each, which will both accommodate a three-lane road. Due to the size and the geological conditions, the construction of the tunnel is considered to be the most challenging part of the overall project. The Italian contractor decided to use mechanised tunnelling technology to improve work safety and to accelerate the works. Accordingly, the Chieti-based company Toto Costruzioni Generali S.p.A. ordered a tunnel boring machine (TBM) from the German company Herrenknecht.

In order to produce the two 2.5 km long tubes of the Sparvo Tunnel, Herrenknecht is developing and building an Earth Pressure Balance Shield with an exterior diameter of 15.55 m, a weight of 4,300 tonnes, a cutterhead power of 12,000 kilowatts and an overall length of 120 m. After completion at the Schwanau plant, the world’s largest tunnel boring machine will then start its work in Italy.

The alternate route is expected to open at the end of 2013.