Satellite-based interferometry for monitoring structural deformations of bridge portfolios

The multi-temporal satellite-based differential interferometry (MTInSAR) is a well-known remote-sensing technique aimed at detecting displacements of persistent scatterers (PSs) on the terrestrial surface. Recent studies motivate research effort on developing efficient and automatic procedures for structural monitoring via MTInSAR. This paper proposes a methodology for the portfolio-scale detection of structural deformations of bridges via MTInSAR. The displacement time-series associated with persistent scatterers on the investigated bridges are used to supply a geoprocessing chain leading to the automatic interpretation of bridge-specific deformation scenarios and the definition of monitoring/assessment priority classes. The methodology is applied to two highway networks in Roma and Bari (Italy) by using Sentinel-1 (C-band) and COSMO-SkyMed (X-band) satellite datasets. Although most of the bridges can be assumed stable, a relevant number of bridges affected by ongoing deformation phenomena are associated with high inspection priority. The PSs and the deformation scenarios related to some specific test bridges subjected to subsidence phenomena are analysed and described in detail. Finally, the deformation scenarios detected through the proposed methodology for two collapsed bridges in Italy are illustrated.