Railway line “Ge Sampierdarena – Confine Francese” – New pedestrian underpass and two lifts to be built at Pietra Ligure railway station (SV).

Project objective

The intervention aimed to equip Pietra Ligure railway station (SV) with a new pedestrian underpass and two lifts connecting the station platform with the platform serving Track 2, in order to provide step‑free access to the second platform; at the time, two at‑grade crossings at the ends of the station platform were used.

Main works

Underpass
The main structure consists of a reinforced‑concrete box culvert with an overall length of 21.36 m and finished internal clear dimensions of 4.40 × 2.90 m; the foundation slab, side walls and top slab are 50 cm thick.
For construction, the “jacked monolith” (box jacking) technique was adopted: a portion of the underpass (monolith) was cast outside the railway footprint, upstream of the line, and subsequently pushed beneath the railway formation by means of a hydraulic jacking system.
The final layout therefore comprises a central section corresponding to the monolith after jacking, 12.60 m long, and two lateral cast‑in‑situ sections, upstream and downstream of the monolith, 5.36 m and 3.40 m long respectively; the lift shafts and the stair‑ramp access structures to the platforms were also cast in situ.
The “jacked monolith” technique provides for the installation of temporary steel girders type “Verona” to support the tracks resting on handling beams: this system is an effective alternative to traditional “rail bundles” and allows, during jacking operations, a theoretical train transit speed of 80 km/h.

Temporary works
To support the excavation walls (maximum depth approx. 6.00 m below ground level), micropile retaining walls were installed in advance (first vertical row Ø220 mm, second rear inclined row Ø127.0 mm), developed along the perimeter of the stair ramps and lift shafts as well as along the perimeter of the upstream and downstream excavation areas required for construction of the in‑situ structures.