PSI - Issue 84

Michela Pulsoni et al. / Procedia Structural Integrity 84 (2026) 214–222 M. Pulsoni et al. / Structural Integrity Procedia 00 (2026) 000–000

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and innovative photo-monitoring techniques applied to two key infrastructures in Turin: the Amedeo VIII Bridge and the Regina Margherita Bridge. The analysis of the geomorphological setting and hydraulic hazard represents a key component of the project. For Ponte Amedeo VIII, the area falls within hazard classes that include zones floodable under the reference flood events (Subclasses IIIa and IIIb2b of the P.R.G.C. of Turin). This implies the potential for flooding and significant variations in the hydraulic regime around the piers, while for Ponte Regina Margherita, the situation is more complex: part of the area lies in classes I–II (absence of, or gradual increase in, hazard), while the portions closer to the river and the fluvial parks fall within classes IIIb2b and IIIb4a, i.e. floodable areas with predominant environmental interest (Parco del Valentino, Parco Michelotti, Parco del Meisino). In the ISABHEL project, images are acquired using cameras permanently installed at the site. The cameras made it possible to obtain significant information on the evolution and displacements of the viaducts. In particular, for Ponte Amedeo VIII two analyses were carried out: a change detection analysis and a displacement analysis (Fig. 5a, Fig. 5b), which highlight variations in the area of material accumulation at the piers. In this case, the change is attributable to the modification of the scene induced by the presence of logs and branches transported by the river and progressively deposited against the piers of the monitored viaduct. The photo-monitoring system was able to detect small changes that are not immediately perceptible to the naked eye. For the same viaduct, a displacement analysis was also performed using the DIC (Digital Image Correlation) technique, shown in the figure, which indicates that the entire accumulation zone adjacent to the piers is subjected to an almost uniform displacement, as also confirmed by the directional arrows obtained from the analysis with the IRIS software. In this case as well, photo-monitoring proves to be an effective tool for accurate monitoring and for supporting the identification of potential intervention measures. With regard to Ponte Regina Margherita (Fig. 5c), a change detection analysis was performed on the entire scene recorded by the camera. In this case, the change detection analysis shows that the main components of the viaduct do not exhibit issues such as degradation, seepage or other structural problems that could compromise the stability or operational use of the infrastructure.

Fig. 5. a) change detection analysis of Ponte Amedeo VIII, b) Displacement analysis of Ponte Amedeo VIII, c) change detection analysis of Ponte Margherita.

The results obtained through photo-monitoring represent the observation level closest to the structure, enabling the detection of localised variations and scenario changes that are not immediately visible to the naked eye. To complete the monitoring framework in a multi-sensor, multi-scale perspective, a satellite-based InSAR analysis was carried out in parallel, aimed at reconstructing the long-term deformation patterns of the viaducts. Satellite A-DInSAR analysis highlights a different behaviour of the two bridges. For Ponte Regina Margherita, both ascending and descending geometries detect measurable settlement at mid-span, with LOS velocities of about 2– 3 mm/year and cumulative vertical displacements up to ~50 mm over 2011–2024. The deformation is mainly vertical (1–3 mm/year), shows seasonal cyclicity superimposed on a progressive trend, while abutments and end piers remain stable, indicating a moderate but ongoing settlement that warrants continued monitoring and ground-based validation. For Ponte Amedeo VIII, velocities along the entire span remain within the stability threshold (<±0.5 mm/year), with only minor seasonal oscillations (±5–10 mm) and flat interferometric profiles, confirming the structural stability of the bridge and clearly distinguishing it from the slightly deforming surrounding ground. Overall, the InSAR analysis demonstrates the capability of satellite monitoring to detect subtle long-term deformations, validate structural stability and complement ground based SHM systems in a multi-scale framework.