Jonio is the first station of B1 metro line in Rome. The station is fully below ground level with the rail level at about 28m depth. A half-circle large building hosting a multi-story car park is located above the station structure.

Considering the significant level difference among the nearby streets, the station excavation was carried out – following an initial excavation – through d-walls (1.2mx3.0m, ‘T’ shape, 2.2m spacing) along with 0.8m diameter piles going at least 5m below excavation level.

The excavation was carried out in a top-down manner with excavations following the construction of the top and intermediate slabs as well as the installation of a bottom plug through 2.2m jet-grouting columns. Such soil improvement (11m thick below excavation level) was necessary both to reduce the actions on the perimeter d-walls and to guarantee a dry excavation under a significant groundwater head (approx. 26m).