Bridge health index: towards an integrated indicator for seismic risk management of road infrastructures

The increasing focus on the resilience of road infrastructures has led the scientific and engineering communities to develop quantitative indicators for assessing the structural condition of bridges. In this context, the Bridge Health Index (BHI) is introduced as a synthetic metric that summarizes the functional, structural, and management conditions of a bridge, including its seismic risk. Internationally, the evolution of BHIs is driven by the need for intelligent monitoring systems, automated assessment algorithms, and data-driven risk management approaches. In Italy, the Guidelines for the classification and risk management, safety assessment, and monitoring of existing bridges together with the Operational Instructions issued by ANSFISA define a structured framework for the use of index-based models. These include knowledge levels, synthetic risk indices, and surveillance systems based on visual inspections, diagnostic testing, and monitoring systems. This paper presents a critical analysis on the integration between international methodologies and national regulations, highlighting the potential of an advanced BHI capable of incorporating structural, geotechnical, and seismic parameters into a unified assessment framework. The goal is to support the development of operational tools for planning intervention, priorities management, and seismic risk mitigation, in accordance with performance-based engineering principles and the digital twin paradigm applied to infrastructure.