Pre- and post-collapse analysis of infrastructures using COSMO-SkyMed satellite data

The Italian territory is characterized by a large number of bridges and viaducts that have reached or exceeded their service life. The primary issue lies in the lack of adequate maintenance and effective monitoring systems. This is confirmed by the growing number of collapses and structural failures that have affected several infrastructures across the country in recent years. These events highlight the urgent need to widely implement Structural Health Monitoring (SHM) techniques across as many structures as possible. In this context, SHM experts are increasingly focusing on the development of innovative technologies capable of monitoring a broad series of infrastructures at a reduced cost. Specifically, contactless methods, such as satellite remote sensing, are gaining particular relevance. Among the various satellite-based techniques, Differential Interferometric Synthetic Aperture Radar (DInSAR) has proven to be an effective tool for monitoring the structural health of existing infrastructure. It enables the detection of millimeter-scale displacements over time, supporting long-term assessments of structural integrity. Although such data have been available and used for many years, several challenges still persist in the SHM context. The only way to address these challenges is through broader application of these data, alongside in-depth studies to understand their characteristics, capabilities, and limitations. This paper presents a study on the investigation the structural behavior of the Albiano-Magra Bridge, which collapsed on April 8, 2020. The analysis is based on the use of high-resolution SAR data from the COSMO-SkyMed constellation, processed using Persistent Scatterer (PS) InSAR approach. Both pre-collapse and post-collapse phases were examined, with the primary aim of detecting potential early warning signals. Additionally, the study focused on identifying Temporary Scatterers (TS) located on the bridge. The results confirm the potential of integrating satellite-based interferometry into SHM strategies.