On the DInSAR technique for the structural monitoring of modern existing bridges

The setting up of efficient strategies for safety assessments and maintenance of modern existing bridges is a crucial research challenge in structural engineering. In Italy, this topic has recently been addressed in guidelines issued by the Ministry of Infrastructures and Transport in 2020. The guidelines outline procedures and tools for safety assessments and maintenance interventions: a mandatory step is the analysis of original documents (concerning the design, the construction process and the maintenance interventions) in order to acquire robust knowledge of the structure. As noted in recent works in the literature, non-invasive structural monitoring approaches play a crucial role in the safety assessment of existing bridges. One such approach is multi-temporal differential synthetic aperture radar interferometry (DInSAR). This paper presents a cross-disciplinary process for the structural monitoring of modern existing bridges, based on integration of DInSAR measurements, exploiting Cosmo-SkyMed measurements collected during the period 2011–2019, and accurate knowledge of the structures derived from analysis of original documents conserved in historical archives. The procedure is applied to two reinforced concrete Gerber bridges in Rome, designed in the 1930s