PSI - Issue 84

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

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Keywords: Multi-level risk assessment; Slope stability; Landslide monitoring; Landslide-bridge interaction. 1. Introduction The Italian infrastructure asset, and particularly existing bridges and viaducts, is increasingly exposed to the combined effects of structural ageing, the geomorphological complexity of the territory, and the intensification of extreme natural events. Among these, landslides represent one of the most critical hazards, especially in mountainous and hilly areas, where the interaction between engineering structures and slope instabilities can significantly compromise structural safety, functionality, and service continuity.Following the collapse of the Morandi Bridge in Genoa in 2018, the safety management system for road infrastructure in Italy underwent a profound revision. The national Guidelines for risk classification and management, safety assessment, and monitoring of existing bridges (LLGG) were first adopted through Ministerial Decree No. 578 of 17 December 2020 and subsequently updated and formally adopted through Ministerial Decree No. 204 of 1 July 2022, which replaced the previous Annex and strengthened their application at national scale. The Guidelines introduced a multi-level, interdisciplinary, and knowledge-based approach, aimed at ensuring methodological consistency, traceability of decisions, and the prioritization of interventions. Within this framework, landslide hazard is recognized as one of the key factors in defining the Class of Attention (CoA) of bridges, alongside structural, seismic, and hydraulic risks. In implementation of Ministerial Decree No. 204/2022, ANSFISA subsequently issued the Operational Instructions for the application of the Guidelines , adopted by the Decree of the President of the High Council of Public Works on 21 September 2022, in order to support their operational implementation by infrastructure managers. Regulatory framework provides a quite clear guidance for the preliminary phases of risk classification (Levels 0– 1 and 2), while operational references need some upgrade for the more advanced stages of assessment, particularly Special Inspections and Level 4 assessments, when bridges interact with active or potential landslides. In such cases, the complexity of bridge–slope interaction requires an advanced knowledge-based approach capable of integrating geological, geotechnical, structural, and territorial aspects, thereby overcoming a purely structural view of safety. In this context, the MARIE project (Methodological Approaches for Risk Assessment in the Framework of Landslide–Bridge Interaction) has been launched by the FABRE Consortium and developed by a group of Italian universities and research centers in collaboration with ANSFISA and major infrastructure managers. The project aims to address existing methodological approach in landslide risk assessment for bridges by providing operational tools, decision-making criteria, and interpretative models to support the application of the national Guidelines. Through the analysis of real case studies, the development of conceptual and numerical models, and the definition of structured knowledge pathways, MARIE seeks to improve the knowledge for the application of guidelines and clarify the role of Special Inspections, define their minimum content, and guide the design of the so-called “Knowledge Project” required for accurate safety assessments. The ultimate goal is to provide a concrete contribution to infrastructure risk management by promoting decisions based on technical evidence and an integrated evaluation of bridge–territory interactions. This paper presents the framework of the analyses developing within the MARIE project, illustrating their underlying assumptions, objectives, and main practical implications, with particular reference to their contribution to the evolution of inspection, assessment, and monitoring practices for existing bridges in landslide-prone contexts. The Guidelines distinguish levels of knowledge, from initial Levels 1–2 to deeper stages that include “Special inspections” and Level 4, defined as complete knowledge. The project clarifies the purpose, scope and triggering conditions of Special inspections for landslide risk and outlines their expected content. It also proposes survey and testing campaigns aimed at achieving Level 4. Activities are conducted with public authorities such as ANSFISA “Italian National Agency for the Safety of Railways and Road and Highway Infrastructure” and with infrastructure managers. The goal is to improve the safety, resilience and service life of critical assets under evolving environmental pressures by refining guideline interpretation and deployment, and by implementing innovative risk-management procedures and effective monitoring strategies. This multidisciplinary, integrated effort addresses key gaps in current practice. © 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference