PSI - Issue 84

Antonio Fiorentino et al. / Procedia Structural Integrity 84 (2026) 757–764

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This knowledge is then translated into operational criteria for the activation and execution of Special Inspections, conceived as a key transitional phase between screening levels and the highest levels of in-depth assessment. Within this framework, the MARIE methodology clarifies the role of Special Inspections not merely as verification tools, but as a knowledge-building phase aimed at supporting well-founded decisions on whether to proceed to Level 4 accurate safety assessment, even in the absence of an overall High CoA. The methodological approach also enables a structured management of presumed or potential landslides, through an extended reading of the context and a cautious, well motivated evaluation of the relevant parameters. A central element of the methodology is the definition, during Special Inspections, of preliminary models—namely the preliminary geological and geotechnical models—conceived as tools for uncertainty reduction and as the technical basis for the coherent set-up of subsequent phases. The MARIE methodology considers these models as the true junction between risk classification and accurate assessment, placing them at the core of the decision-making process. A substantially different methodological approach is required for slow-moving landslides and rainfall-induced processes (soil slip). In the latter case, the assessment focuses on the identification and evolution of potential source areas and mobilizable volumes, using physically based models such as SLIP (Montrasio et al. 2023). Within this framework, Special Inspections are required only in specific cases, primarily to support model application.

Fig.3. Statistical characterization of landslide–bridge interaction cases: distribution of landslide types (with comparison against the Italian Landslide Inventory-IFFI and European inventories), and distributions of landslide volumes and velocity/activity classes, highlighting the predominance of slide-type mechanisms and mainly slow to very slow kinematics, with a non-negligible share of rapid events (after Gabrieli et al., 2024). 3.2. Special Inspections Within the MARIE methodological framework, Special Inspections are defined as the mandatory operational step linking screening-based classification activities to Level 4 accurate safety assessment in contexts characterized by landslide risk. They shall not be interpreted as simple “additional” investigations; rather, they shall verify whether an actual or potential landslide–bridge interaction may result in: (i) structural or foundation distress conditions, evident or incipient; and/or (ii) safety margins incompatible with continued service under ordinary operating conditions. Within the MARIE project, activation criteria have been clarified. Special Inspections shall be activated when one or more of the following conditions occur: (a) the structure is located in areas affected by documented or suspected