Satellite InSAR Technology for Displacements Monitoring of Bridges: A Comparison with Onsite Topographic Measurements and Uncertainty Quantification

Abstract

Satellites equipped with Synthetic Aperture Radar (SAR) sensors can capture millimetre-scale displacement of the Earth's surface and man-made structures regardless of atmospheric conditions or lighting. Over the past two decades, Interferometric SAR (InSAR) has found many applications, including monitoring subsidence, volcanoes, and glaciers. While there have been some applications in civil engineering, a metrological validation of satellite technology for remote structural health monitoring (SHM) compared to traditional on-site SHM is lacking or inconclusive. This research aims to validate the use of satellite based InSAR technology for SHM of road bridges by directly comparing the time series of displacement extracted with InSAR on the Colle Isarco Viaduct, Italy, with those obtained by on-site topographic monitoring. This study also compares the deformed shape of a subpart of the bridge, which is modelled based on satellite and on-site measurements, to verify the possibility of reconstructing the bridge distortion over time based only on satellite data. The goal is to analyse this new technology's accuracy and reliability and identify its strengths and limitations. If deemed reliable, this technology could simultaneously monitor many civil infrastructures at a significantly lower cost than traditional site monitoring systems.