Multi source Interferometry Synthetic Aperture Radar for monitoring existing bridges: a case study

Bridge maintenance and safety are key goals for transportation management com-panies, considering that several vulnerability sources can affect these assets. Alt-hough necessary and hardly replaceable, traditional surveillance techniques repre-sent time- and cost-consuming activities that cannot be widely employed on the entire infrastructural portfolio. Hence, innovative techniques could be exploited, among which the use of Interferometric Synthetic Aperture Radar (InSAR). InSAR is a well-known remote sensing technique that allows to reconstruct the displace-ment time-series of persistent scatterers (PS) on the Earth's surface. The current available PS time series present different levels of spatial accuracy and temporal frequency, which depend on satellite data source. On this base, the paper deals with the evaluation of displacement scenarios for existing RC bridges, by means of two different popular satellite time-series datasets: Sentinel-1 and COSMO-SkyMed. In detail, the analysis of the interferometric products provides different out-comes, which are discussed in this paper. Pros and cons are provided with reference to a real-life case study, showing differences in terms of geometry, resolution, and dis-placement results.