PSI - Issue 78

Manuel Capogna et al. / Procedia Structural Integrity 78 (2026) 1064–1070

1065

Keywords: Segment-Based Risk Classification; Bridge Assessment; Multi-Hazard Analysis; Infrastructure Resilience; Digital Twins

1. Introduction Effective management and assessment of existing civil infrastructures are paramount for ensuring public safety and optimizing maintenance strategies. In Italy, the Ministry of Infrastructure and Transport has issued distinct guidelines for the classification and risk management of various infrastructure types. Specifically, separate guidelines exist for bridges and road tunnels (Italy, 2022, 2020). While the tunnel guidelines introduce a sophisticated segment-based approach, allowing for a detailed, localized risk evaluation through "conci" (homogeneous units) and the assignment of partial and global attention classes, the current methodology for bridges adopts a singular, structure-wide attention class. This disparity in granularity can lead to an oversimplified assessment of bridges, especially complex or long viaducts, potentially obscuring critical local vulnerabilities. This paper proposes an extension of the segment-based risk classification methodology from road tunnels to bridges, aiming to provide a more detailed and accurate representation of risk distribution along these structures, thereby enhancing infrastructure assessment and informing targeted interventions. 2. Current methodologies and their limitations The evolution of Italian regulations for infrastructure inspection and maintenance highlights a continuous effort towards more systematic management. Early circulars, such as Ministerial Circular No. 6736/61/A1 of July 19, 1967, focused on ensuring structural stability, while subsequent regulations like Ministerial Circular 34233/1991 of February 25, 1991 moved towards a more systematic management of civil works. The introduction of new technical standards for construction (NTC) in 2018, brought forth the concept of structural durability, signifying a shift from merely resistance-based assessments to considering the time-dependent degradation of materials and structural properties. More recently, the italian bridge guidelines issued in 2020 and recently updated, represent the current operational standard for managing road bridges, introducing a multi-level risk assessment system (Buratti et al., 2022; Renzi et al., 2023a; Renzi et al., 2023b) Despite these advancements, the current italian bridge guidelines primarily assign a single attention class to an entire structure, irrespective of its complexity, length, or varying conditions along its span. This contrasts sharply with the tunnel guidelines, which employ a segment-based approach, dividing the infrastructure into homogeneous units (conci) (Carigi et al., 2024). This allows for the evaluation of both 'partial' and 'global' attention classes, providing a granular understanding of critical tunnel conditions, further enhanced by percentage-based diffusion indexes (see Fig.1).

Fig. 1. Synthetic representation of a Tunnel - Attention classes for each individual segment and diffusion index table