PSI - Issue 84

Federico Foria et al. / Procedia Structural Integrity 84 (2026) 296–303

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sectional shape for potential changes by taking periodic measurements and plot ground and groundwater conditions along the tunnel profile to identify deficiencies and determine if ground conditions are contributing to problems In this paper the aspects specifically concerning the Italian Guidelines, whether they relate to existing bridges or tunnels, are enhanced for railway lines (although the Guidelines are not specifically tailored to these) thanks to an integrated approach developed and implemented by ETS and called “MIRETS Hydrogeological Mapping”; the latter is based on mobile surveys, geospatial analysis and information modelling, with a particular focus on detailed geomorphological mapping and risk assessment. In particular, the presented high-level, systemic approach allows for the prioritization of interventions, operational efficiency, and long-term sustainability as demonstrated in two case studies chosen along the railway lines of Central Italy. 2. Italian guidelines: general principles The Guidelines of the Higher Council of Public Works on existing bridges (HCPW, 2022a) outline a six-level procedure, each characterized by an increasing degree of detail, which ranges from a simple census of the works to the determination of the Attention Class and, in certain cases, to in-depth assessments. The central focus of the approach is level 2, e.g. the definition of the Attention Class of the work. It is considered misleading to speak of actual risk, as its analysis requires more complex assessments, while the Attention Class is an approximate estimate of risk factors useful for defining an order of priority for future interventions. There are five levels of attention, corresponding to increasing degrees of control over the structure, defined through the well-known risk assessment model, which is derived from the combination of three fundamental elements: hazard, vulnerability and exposure. These factors are determined by analyzing the main parameters that influence them, divided into primary and secondary parameters. The factors are determined using a ‘classes and logical operators’ approach, e.g. by grouping each main and secondary parameter into classes and combining the classes with each other using logical flows. The process then leads to the determination of the hazard, vulnerability and exposure classes, which are in turn combined into the Attention Class of the structure. The classification is determined according to the possible relevant risks: structural and foundation, seismic, hydraulic and landslide, which are initially analyzed separately and then combined into a single overall Attention Class. On the other hand, in the Guidelines of the Higher Council of Public Works on existing tunnels (HCPW, 2022b), the proposed procedure is aimed at determining the “Attention Class” related to various risk factors (including structural, geological, seismic, hydraulic) based on classes and logical operators. The logical flow starts from the classification of primary and secondary parameters to the classification of hazard, vulnerability, and exposure factors, and finally to the determination of the “Attention Class” for each considered risk factor. The general structure adopted by the Italian guidelines for defining the Attention Class (CdA) is as follows:

Fig. 1. Attention class evaluation workflow according to Italian Guidelines (2022).

The input parameters necessary for estimating the landslide attention class for tunnels and bridges are described in the next Section.

3. Italian guidelines: details on tunnels and bridges for the estimation of the Landslide Attention Class In the Guidelines of the Higher Council of Public Works on existing bridges (HCPW, 2022a), the Landslide Attention Class refers to susceptibility, vulnerability and exposure factors, determined by combining the parameters