Webuild, which was awarded the contract by Rete Ferroviaria Italiana (RFI) for the Naples-Cancello lot of the Naples-Bari high-speed/high-capacity railway line, is using hyperbaric excavation for the construction of a 650 m section of the 3.3km Casalnuovo artificial tunnel. Which runs partially under the water table while passing through a highly urbanised area.
A fundamental characteristic of hyperbaric excavation is the use of compressed air as a method to carry out excavation operations in the presence of water. The pressure introduced into the site keeps water out of the working areas, which benefits the environment in that the aquifer does not come into contact with cement mixtures and chemical additives.
Trained workers enter the hyperbaric area through gradual adaptation in a special compensation chamber that provides for a maximum of 20 workers per shift. Gradual compression in the chamber lasts an average of 20 minutes. Depending on the excavation phase, the pressure fluctuates between about 0.3 and 1.2 atmospheres. All activities are carried out following procedures and specific technical and health protocols that ensure the highest safety and health for workers.
The construction of the Casalnuovo tunnel, which is scheduled to be completed by mid-2025, involved the preparation of complex and innovative plant engineering, developed with the involvement of specialised technicians and highly qualified international suppliers.
Webuild works - commissioned by Rete Ferroviaria Italiana - are proceeding in parallel on the other lots of the line. Two new TBMs are currently being assembled and will be used to start the excavation - scheduled for summer - of the 6.4km Rocchetta tunnel (Apice-Hirpinia lot) and the odd tube of the 10 km Orsara tunnel (Orsara - Bovino lot). Meanwhile, the excavation of the Grottaminarda Gallery, about 2 km long, is also continuing on the Apice-Hirpinia Lot, with about 60% of the route constructed and expected to be completed by summer.
Webuild is engaged in the construction of the four Napoli-Cancello, Apice-Hirpinia, Hirpinia-Orsara and Orsara-Bovino lots of the HS/HC Napoli-Bari line: over 74 km of new railway line, 6 tunnels for the excavation of which the use of 8 TBMs is planned, 10 viaducts for about 6 km and 6 new stations and stops: Acerra, Casalnuovo, Hirpinia and Orsara, Centro Commerciale and Apice.
In total on the future high-speed line between Naples and Bari will be 145 km long there will be, 9 tunnels (including the 27 km Hirpinia tunnel, which will compete with the Valico tunnel in Genoa for the record for the longest tunnel in Italy), 25 viaducts and 16 new stations and stops.
At the end of the work on the entire Naples-Bari line, scheduled for 2028, it will be possible to go from Naples and Bari in 2 hours, compared to about 4 hours today, and Rome and Bari in 3 hours. The HS/HC Naples-Bari line will also bring significant benefits in terms of environmental sustainability, allowing more than 3 million tonnes of CO2 emissions to be avoided in the period 2023-2047.
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