PSI - Issue 84

M. Cademartori et al. / Procedia Structural Integrity 84 (2026) 384–391

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1. Introduction The problem of the management of existing bridges on the Italian road network it is currently of extreme importance, given that most of the structures have overseed its design lifetime and that the road and rail traffic, in terms of flow and loads, has been tremendously incremented. The age of existing bridges, the traffic demandand the natural hazards are important aspects to be considered in the maintenance process for correct Asset Integrity Management (AIM). The tragedy of the collapse of the Morandi bridge in Genoa occurred in August 2018 highlighted the need to expand the range of action of the national code in terms of structural assessment of existing roads and highways (Calvi et al, 2018). This event delineates a total change in the history of the bridge assessment in Italy and in Europe and led to the publication of guidelines by the Italian Ministry of Transportation (MIT) (MIT, 2020), herein referred to as “the Guidelines” or as LLGG. In 2022, the current version of the LLGG was released following a period of experimental application on Italian highways (MIT, 2022). These guidelines aim toconsolidatethe various threads of research in this field, and it is the first document in Italy specifically dedicated to bridge management and bridge load rating. Starting from the release of the first version of the Guidelines in 2020, the authors have been involved in several assessment programs in Italy and in other countries dealing with different kinds of bridges and viaducts. Thanks to the application of the Guidelines for different bridges and for different clients and thanks also to the international experiences of the authors, the aim of this work is to present some of the peculiarities of the assessment process. An extensive research work devoted to the publication of practical procedures for the better explanation of some elements related to the bridge assessment is currently ongoing by the RELUIS Consortium in Italy (Italian network of the university laboratories of seismic and structural engineering). As part of this project, throughout 2026 several guidelines will be published to assist the engineer during the assessmentprocess. Inthe following, some of the main highlights deemedto be useful for practical applications and future improvement of the Italian Guidelines are provided based on the recent experiences of the authors. In the first part, a review of the available codes and regulations applicable to the assessment of bridges within the Italian and International context is presented. Then, the study highlights the critical issuesencounteredduring the knowledge phase, introducing the concept of the Performance-Based Testing campaign, and analyzingsome typical issues that engineers must address during the assessment procedures. Finally, the analysis of the results of the bridge load rating procedure applied to a big portfolio of bridges is presented. This study offers practical insights for engineers/managers dealing with the assessment of bridges and helps identify the peculiarities and elements that should be included from the beginning of the assessment process, as well as aspects that need further development within the regulatory framework. 2. National and International codes and regulations Bridge design and bridge assessment share similar principles but evaluating existing bridges requires considering a broader set of variables. Unlike design, being overly conservative during assessment can lead to unjustified load restrictions or costly interventions. In Italy, early regulations focused mainly on inspections: the first national code appeared in 1967 but did not address load rating or seismic verification. A more modern framework emerged only after the 2003 Molise earthquake, with OPCM3274 introducing seismic provisions for bridges. Further progress came between 2005 and 2009 through the RELUIS research guidelines for seismic assessment. The 2018 Italian Technical Standards (NTC18) included general criteria for evaluating existing structures, later amended by CIR19, which for the first time acknowledged the need for reduced reliability levels when assessing older structures. The collapse of the Morandi Bridge in 2018 marked a turning point, leading to the first dedicated national Guidelines for bridge monitoring and assessment (2020, updated 2022). These guidelines introduced new vehicular load models, partial factors aligned with the fib APFM method (FIB, 2016), and different reliability objectives. A detailed review of the application of the Guidelines to a stock of Italian bridges for the definition of the structural foundational and seismic risk classification can be found in Salvatore et al (2024). However, the Guidelines still lack detailed procedures for different bridge types and give limited indications on testing campaigns, leaving much to engineering judgement.