Work on the first part (completed in 2012) involved a 3.6 km long section formed by excavating a twin bored tunnel using 2 EPB TBMs with a 6.79 m diameter. The second part is formed by a tunnel linking the stations of Conca d’Oro and Jonio, built between 2010 and 2015 with a 8.65 m large diameter double-track tunnel (1.1 km long), using 1 EPB TBM with a 9.77 m diameter.

The excavation work required the use of highly sophisticated solutions to tackle soils with a poor geo-mechanical characteristics crossed by aquifers. The need to work on this project in a densely populated area where important buildings were located meant that special attention had to be paid to eliminating any risk of damaging above-ground structures.