Work continues at full speed for Impresa Pizzarotti & C. S.p.A., activities at the Ariano Irpino site for the construction of the launch shaft for the two TBMs that will excavate part of the future Hirpinia tunnel, one of the most strategic junctions of the HS/HC Naples-Bari axis.

The launch shaft is a temporary and strategic structure that allows the safe assembly and lowering of the mechanical mole head. It is used when excavation cannot be started directly from a tunnel portal (e.g. for reasons of space, slope or environmental constraints). The shaft also provides vertical access that is useful for moving materials, ventilating the tunnel during work and managing safety during excavation.

We are currently 13 metres deep out of a total depth of 26: the reinforcement of the third level of the concrete contrast beam is in progress. At the next level, temporary metal struts will be installed, which will ensure the stability of the bulkheads during the subsequent phases.

Once this step is also completed, excavation will continue up to the height of the 1.5 metre thick foundation slab. After the slab has been cast, the temporary struts will be removed to allow the TBMs to be lowered, a key operation for the start of mechanised excavation.

The two TBMs, which will be lowered from above through a large 21.5×13 metre slot, will begin excavation in the direction of Bari, creating the 27 km Hirpinia tunnel: the longest tunnel in Italy together with the Third Valico dei Giovi tunnel. The final configuration envisages a single-track double tube, with a transition to a single-track double tube near the entrance on the Naples side.

The shaft is constructed using a top-down methodology between reinforced concrete bulkheads and multi-punched diaphragms, which allow safe excavation in a complex geotechnical context. Once the launch shaft function has been completed, the top slot will be converted into a ventilation shaft, serving the safety of the tunnel.

This construction site is a concrete example of advanced engineering and construction capacity: Impresa Pizzarotti is proud to contribute its experience to the realisation of a fundamental infrastructure for the country.