Safety assessment of bridges: analysis and criticalities of the guidelines for hydraulic risk management

Italian territory is characterized by a high fragility in terms of hydrogeological risk. Therefore, the national structural heritage needs the implementation of risk assessment plans. Specifically, the interaction between infrastructures and water has been identified as a significant factor contributing to recent collapses and failures. The existing Italian national guidelines for evaluating infrastructure vulnerability may fail in accurately reflecting the actual hydraulic conditions. This study aims at evaluating the strengths and limitations of the analyses pursued according to the guidelines and conducted on an impressive dataset comprising 51 bridges located in Italy. Common critical issues have been identified which potentially lead to incorrect estimations of the associated risk level. An erroneous risk assessment can result in misallocation of time and financial resources. One major challenge lies in the difficult tracing of original design documentation, which negatively impacts the assessment process and it may results in overestimating vulnerability to both generalized and localized erosion. Other significant challenges include the lack of specific directions for particular cases and difficulties in accessing the bridges (e.g. the morphology of the terrain or the dense vegetation in floodplain areas). While the guidelines provide an effective framework for risk analysis and damage prevention, they should be used in a critical way to identify and address any deficiency. This assessment may lead to an integration of the methodology and thus, of the guidelines, ensuring improved reliability and ease of application. Our study presents statistical metrics of infrastructure vulnerability estimated based on the guidelines. These analyses have successfully identified several strengths as well as critical aspects related to evaluating hydraulic risk based on guidelines implementation leaving space for opportunity of improvements.