PSI - Issue 78

Carmine Lupo et al. / Procedia Structural Integrity 78 (2026) 185–192

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parameter derived from the velocity attenuation function and it is used to consider the influence of epicentre distance in different events of the same magnitude, see Sabetta and Pugliese (1987). 2. Overview of Italian Bridges The Italian territory is characterized by a complex and articulated morphology, which has necessitated the construction of a substantial number of bridges, viaducts, and tunnels. In particular, the national road network extends for over 180,000 km, comprising approximately 6,700 km of highways, 19,800 km of state roads, and up to 100,000 km managed by provincial authorities. Based on available estimates reported by Ministry of Infrastructure and Transport (2019) and Pierluigi (2019), the infrastructure assets can be quantified as follows: - A total of 3 international tunnels (25.4 km), 566 tunnels (516 km), and 1718 bridges and viaducts (681 km) along the toll highway; - Approximately 1200 tunnels and 11000 bridges and viaducts along the network managed by ANAS (motorways and state roads); - Approximately 30000 bridges, viaducts, and tunnels along the roads managed by the provinces. In an ever-changing world, it has become necessary to have an efficient and safe road network, to guarantee an optimal service to the users, allowing the social and economic development of a country. It is evident that bridges and tunnels represent the most vulnerable components of a road network. The era in which the construction of Italian roads flourished was the period following the Second World War. Italy is also characterized by a highly complex and heterogeneous territory, which is subject to multiple natural hazards and risk factors, including seismic, volcanic, hydraulic, and hydrogeological phenomena such as landslides and floods, according to ISPRA (2021) and CNR-IRPI (2022). This intrinsic fragility is evidenced by both historical and recent catastrophic events, including the 2009 L'Aquila earthquake, the 2012 Emilia-Romagna seismic sequence, the 2016 – 2017 Central Italy earthquakes (INGV, 2020 and De Biagi et al. 2021), the ongoing bradyseismic activity in the Campi Flegrei volcanic are a (D’Auria et al. 2023), the 1998 Sarno landslides and recurrent flood events such as the 2023 Emilia-Romagna. These events highlight the persistent vulnerability of the national infrastructure system and underscore the need for continuous monitoring, risk assessment, and mitigation strategies. A turning point in the Italian approach to infrastructure management occurred following the tragic collapse of the Polcevera Bridge in Genoa in August 2018, which revealed systemic deficiencies in the monitoring and maintenance of critical transport infrastructure. In response, national authorities introduced the LG20, officially adopted by the Ministry of Infrastructure and Transport in 2020. The implementation of LG20 has contributed to a paradigm shift by promoting a systematic and risk-based classification of existing bridges, integrating structural condition assessments, vulnerability indices, and prioritization of maintenance interventions. Initial applications of the LG20 framework, carried out by ANAS, ASPI, local managing bodies, regional authorities, and academic institutions, have revealed a widespread lack of up-to-date inspections, documentation, and planned maintenance on road infrastructure, particularly among older bridges constructed during 1950s – 1970s, as observed by Zonta et al. (2021) and Brühwiler et al. (2022). These findings have led to the emergence of structured digital inventories, the adoption of bridge management systems (BMS), and the integration of decision-making tools based on multicriteria or Bayesian approaches for asset prioritization, as explored by Caprili et al (2021) and Inaudi et al (2023). In this context, in 2020 the Inter-University Research Centre for the Prediction and Prevention of Major Hazards (CUGRI) launched a joint Applied Research project with the Southern Highways Company (SAM), which is currently being carried forward in collaboration with the present managing body, Naples-Pompeii-Salerno S.p.A. (SIS-SPN). The conducted activities have played a pivotal role in systematizing inspection data and enabling large-scale condition assessments of infrastructure, as documented by Petti et al. (2023), Petti et al. (2024), Lupo et al. (2024). The adoption of the LG20 guidelines as a methodological framework facilitated a structured preliminary evaluation of the existing assets, integrating both the degradation state of structural elements and their exposure to natural and anthropogenic hazards. This dual-level evaluation approach has made it possible to characterize the current condition of bridges and viaducts, both in terms of observed damage mechanisms and through the assignment of an Attention Class (CdA) to each structure. This classification is based on a combined analysis of vulnerability, structural criticality, and risk exposure.