A MTInSAR-Based Early Warning System to Appraise Deformations in Simply Supported Concrete Girder Bridges

This paper presents an early warning system to investigate deformations in simply supported concrete girder bridges over time, using the information content provided by satellite data, integrated with other available sources. The safety of the existing bridges is a priority for transportation management companies, which should carry out continuous and accurate monitoring campaigns, by exploiting traditional time- and cost-consuming activities that cannot be widely applied to a bridge portfolio scale. To reduce management costs and to define reliable prioritization schemes, new cost-effective technologies can be involved such as the satellite-based Multi-Temporal Interferometry Synthetic Aperture Radar (MTInSAR). This technique can represent a valuable option for observing the displacements induced by different actions and to relate the identified behaviour to possible or future fails. This paper presents an early warning system aimed at exploring possible anomalies in simply supported reinforced concrete girder bridges by efficiently elaborating MTInSAR, combined with additional data (e.g., environmental temperature and structural information knowledge). The proposed framework allows manipulating the persistent scatterers' information to derive longitudinal and vertical displacements over time. These are compared to appropriate thresholds leading to potential early warnings aimed at supporting road managers in undertaking future surveillance actions. The proposed procedure was tested on a case study, defined according to the most spread typology of bridges in Italy. This application highlights the advantages of the proposed framework which allows for a cost-effective long-term monitoring with outputs that can be automatically updated over time and suitable for network-scale early warning detection.