PSI - Issue 84

Mirza Adeel Zeb et al. / Procedia Structural Integrity 84 (2026) 256–263

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consistency suggests that the observed subsidence is part of a broader ground deformation process affecting multiple assets within the same subsidence bowl, rather than an isolated structural issue. From an engineering perspective, this spatial coherence indicates that mitigation and monitoring strategies should be developed at the local network scale rather than individual structures. Bridges B186 (Fig. 4e, 5c) and B234 (Fig. 4f) exhibit lower, yet significant, subsidence rates of approximately - 5.5 mm per year, resulting in cumulative settlements of 26 mm. Notably, bridge B234 shows a slight increase in subsidence rate after 2021. A subsequent comparison of InSAR-derived displacement trends with visual inspection results confirms that the observed structural conditions correspond closely to the remotely sensed ground motion. Cracks, fissures, and localized settlement documented in photographs confirm the critical conditions, independently validating the EGMS-GIS methodology and corroborating the detected deformation patterns.

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Fig. 5. Photographs show real time deformation long three bridges. (a) B34, (b) B119, (c) B186

This analysis extends beyond snapshot velocity estimates by quantifying progressive, cumulative displacement, which represents the primary driver of differential settlement and increasing structural risk. The solid lines in Figure 3 represent the linear regression fit for each detrended series. This visualization is critical for transitioning from instantaneous velocity assessments to an understanding of progressive, cumulative deformation, which is the primary driver of escalating structural risk. By integrating time-series kinematics, spatial coherence among neighbouring bridges, and visual inspection data significantly advances the connection between satellite-based observations and practical engineering decisions. 5. Conclusion This study demonstrates how deformation data from the European Ground Motion Service (EGMS) can be effectively integrated with GIS-based infrastructure inventories to support the assessment and management of bridges and viaducts affected by land subsidence. The analysis identifies a well-defined subsidence bowl in the Caserta alluvial plain, with vertical ground displacement rates locally exceeding −5.5 mm/yr and reaching up to −10 mm/yr in the most critical areas, consistent with the distribution of compressible Quaternary deposits and long-term groundwater extraction. At the territorial scale, the GIS-based screening identified 16 bridges and viaducts out of 250 located within zones of significant ground motion, exhibiting average subsidence rates between approximately −4.6 and −7.5 mm/yr. This preliminary assessment provides a rational basis for prioritizing assets for further investigation and supports the efficient allocation of monitoring and maintenance resources. To complement velocity-based indicators, a time-series kinematic analysis was conducted on six representative bridges. EGMS data reveal persistent, near-linear subsidence between 2019 and 2023, with cumulative ground displacements reaching approximately −4 7 mm for the most critical bridge (B34 - Agnena). It should be emphasized that these measurements describe ground surface movements rather than directly quantifying potential differential settlements of the structures; however, such soil deformation has, in some cases, contributed to settlement-related structural issues by increasing demand on foundations, piers, and bearings. Integration of remotely sensed deformation data with previous on-site inspections confirms the reliability of the proposed methodology. Observed damage patterns, including cracking, fissuring, and settlement-induced deformations, are consistent with the subsidence trends detected by InSAR, particularly for bridge B34, where the