Geomorphological risk factors for river bridges

Hydraulic phenomena likely constitute the predominant factor behind global occurrences of bridge collapses. A database of the Italian river bridge collapses and/or severe damage that occurred from 2000 to 2023 is now available, including their locations, the main characteristics of the associated river systems, and details of the hydraulic processes that caused failure (vertical erosion, lateral erosion, hydraulic load, etc.). In the absence of a registry of bridges in Italy, the annual failure rate of hydraulic bridges can be estimated using the number of river crossings on the national territory. By comparing the characteristics of river systems associated with collapsed bridges to those of a reference sample, the risk of failure can be evaluated in correlation to some basic parameter of the hydrographic basin. The data required for the analysis are easy to calculate using a digital terrain model. Therefore, the results can provide valuable assistance to bridge managers in establishing potential criticality rankings, facilitating the planning of detailed risk assessments.