PM&D Engineering carried out the executive and construction design of the structural variants for three road bridges and one railway bridge, as part of the ANAS project to upgrade and improve the functionality of the Rieti interchanges.

The structures, all single-span with composite steel-concrete decks and seismic isolation devices, include:

A3 Bridge, over the Ranaro stream (35.80 m span): a new crossing serving the road alignment, with the existing historic bridge preserved as a pedestrian path.

A4 Bridge, over the Ranaro stream (31.30 m span): a new bridge built alongside the historic structure, avoiding invasive modifications to the existing masonry.

C3 Bridge, over the Turano River (structural span increased from 29.76 to 49.00 m, overall deck length 50.20 m): demolition and replacement of the existing bridge, removing the in-river piers to improve hydraulic flow and reduce scour risk. The design also included a foundation variant developed during construction — replacing large-diameter bored piles with a micropile system better suited to the presence of groundwater — achieving a cost saving of around 10% of the work’s value. The 270-tonne steel deck was assembled on site and launched from below on 28 February 2025 using a 1,250-tonne crawler crane.

C7 Railway Bridge, on the RFI Terni–Sulmona line: PM&D Engineering also provided, under a direct assignment from ANAS S.p.A., technical assistance to the Site Management and the client during the structural load testing of the new bridge.

The service required a coordinated approach spanning structural design, hydraulic verification, seismic isolation, special foundations in the presence of groundwater, and management of the most critical construction phases, up to the major lifting operation of the C3 Bridge.