The developed construction project covers the first lot of the section Nesima-Monte Po for a total length of 1.9 km, entirely developed into the single-tube tunnel with double track. The excavation, right in the middle of the town, features a minimum 10 to maximum 25 meters cover. This area, considering the well-known geological and morphological complexity related to the chaotic structure of volcanic formations, is also characterized by a complex hydrogeological structure.
The interaction of the aquifer with the project works, with particular respect to the open-pit excavation works (launch shaft, reception pits and balance openings) has been the subject of studies and design in details, resulting in the definition – during the works implementation – of all the works and/or preparation activities for the groundwater monitoring, management and related waterproofing systems.
The whole project is part of the program for upgrading and transforming the railway line commenced by the Circumetnea Railway, which will gradually transform the existing narrow-gauge line into the electrified standard-gauge line.
The construction design, based on the highly anthropized surrounding environment and the works inherent characteristics of complex underground infrastructures, was developed with particular focus on both specific and broad-ranging options, achieving the primary targets of minimizing the impact of the works and sites on the strongly populated urban fabric, optimizing the excavation progress methodology, as well as the stations refunctioning and the excavated soil and rock management.
The preferred option to fulfill the needs of the Contracting Authority, the stakeholders and the whole community involved, envisages the entire tunnel execution by TBM-EPB, the earth pressure balanced shields tunnel boring machine, which is capable of providing absolute and evident added value in terms of maximum safety, minimal impact and assurance of performance quality and implementation time.
The new subway section, together with the main works of art, was designed with the aid of the BIM technology to obtain the development of 3D models interfacing with all the main project components: three-dimensional graphic modeling, f.e.m. modelers for structural and geotechnical calculations, tracking and calculation software.