PSI - Issue 84

L. Fieno et al. / Procedia Structural Integrity 84 (2026) 1127–1135

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On behalf of ANAS, we dealt with another structure that was entirely similar, albeit situated along a regular roadway.

Figure 6: Longitudinal view of the bridge

Figure 7: Longitudinal section of the bridge and cross-section of the arch at the crown.

The main damage observed during the visual inspections carried out in 2025 is summarized below. In general, the structure exhibits various cracking patterns and deterioration phenomena primarily affecting the piers, the longitudinal beams, and the cross-beams. The arch box shows, in some areas, passive moisture staining and, locally, evidence of active seepage. In addition, the box exhibits voids/honeycombing at the intrados in correspondence with certain construction joints. From some of these voids, runoff traces are visible, associated with locally washed-out concrete. To increase the level of knowledge of the structure, a dedicated investigation campaign was planned, including the extraction of reinforcement and concrete samples to determine the mechanical properties of the structural elements, as well as reinforcement mapping by covermeter measurements. These activities were supplemented by: (i) a 3D laser scanner survey, producing a point cloud from which several dimensions—unavailable or unreadable in the as-built documentation—could be derived; and (ii) endoscopic inspections aimed at investigating the origin of the water runoff observed along the arch intrados. Through these endoscopies, using a micro-camera, it was possible to inspect the internal condition of the box cells, which in most cases were found to be dry and free of runoff traces. In some cells, however, the presence of water was detected, likely due to infiltration from the extrados of the box section. The deterioration observed on the arch deck is not advanced and currently allows satisfactory operation under the governing traffic load effects, albeit with the necessary restrictions on heavy vehicles. From a seismic safety standpoint, also considering the high seismic hazard of the area, the bridge is vulnerable and does not meet the parameters required by the current Italian Technical Standards for Construction (NTC 2018). Nevertheless, achieving a full seismic upgrade is particularly complex and costly because the bridge is an upper-deck arch structure with monolithic connections and no bearings; any attempt to alter the static scheme would be extremely delicate. In particular, during the visual inspection carried out using the By Bridge system, a through crack was observed on the tallest pier, which led the client to immediately impose traffic restrictions on the overpassing roadway and to initiate the design of interventi in somma urgenza (emergency works under Italian regulations), aimed at reopening the structure under condizioni di transitabilità ai mezzi pesanti (44 t) , i.e. allowing the passage of heavy vehicles up to 44 t.