PSI - Issue 84

Francesco La Fortezza et al. / Procedia Structural Integrity 84 (2026) 368–375

369

Keywords: Highway bridges, Exceptional transport loads, Long-span bridges, Exceptional actions.

1. Introduction In July 2022, the “Linee Guida sui trasporti in condizioni di eccezionalità” [1] (hereinafter LG TE) were issued by Ministerial Decree No. 242 with the aim of defining a unified regulatory and technical framework for the management of exceptional transports across the entire national road and motorway network. These Guidelines are part of a broader process of updating the legislation on the safety of road infrastructure, introducing more structured and homogeneous criteria for assessing the passability of exceptional vehicles, particularly in relation to major structures and superstructures (pavements). The entry into force of the LG TE, originally scheduled for an earlier date, has been subject to repeated extensions. The current deadline for the full effectiveness of the Guidelines is set for March30,2026, until which date the transitional regime provided for by the Highway Code continues to apply. One of the most innovative aspects introduced by the LG TE concerns the management of major structures such as bridges, viaducts, and overpasses, for which a merely administrative assessment of transit is no longer sufficient; a precise structural technical verification is required. In particular, the Guidelines provide for the introduction of traffic load models dedicated to exceptional vehicles, designed to represent different transit scenarios on the structure, taking into account load distribution, vehicle position within the carriageway, and the operating conditions of the infrastructure. Passability assessments must be carried out in accordance with Ministerial Decree No.247 of July1,2022 “Linee Guida per la Classificazione e Gestione del Rischio, la Valutazione della Sicurezza ed il Monitoraggio dei Ponti Esistenti” [2] e “Istruzioni Operative per l’applicazione delle Linee Guida per la Classificazione e Gestione del Rischio, la Valutazione della Sicurezza ed il Monitoraggio dei Ponti Esistenti” [3], updated with CSLP Decree No. 413 of November 5, 2025, using an integrated approach to assess the residual structural safety level of the structure and the compatibility of the requested transit. This approach represents a significant step toward more informed, engineering-based management of existing infrastructure, especially in the presence of exceptional loads. Within this regulatory and technical context, SINA, an engineering company of the ASTM Group, has implemented the content of the LG TE into an operational decision-support tool for motorway concessionaires. The main objective was to develop dedicated software, called TES, capable of performing structural analyses on individual major structures and supporting the evaluation process necessary for granting authorisation and any conditions for the transit of exceptional vehicles. The starting point for the TES application development was the finite element modelling of the major structures on the networks managed by the individual concessionaires. Representative structural models were constructed for each structure, and sectional checks were performed in the engineering-significant zones, such as mid-span and support sections. These checks made it possible to evaluate the structural response of the structures under the various load schemes provided by the LG TE and to identify any critical issues related to exceptional transits. The modelling and verification activities enabled the creation of a structured database containing technical information and models for all major structures pertaining to each concessionaire. This archive represents a fundamental element for the systematic management of transit requests, allowing quick and coherent access to the data needed for technical evaluations. Subsequently, a user-friendly web application was developed, designed to make the tool easy and intuitive to use even for non-specialist users. The interface, accessing directly the database of modelled structures, simplifies and speeds up the authorisation process for exceptional transport requests. In particular, the application allows the user to define the entry and exit points of the exceptional vehicle on the infrastructure network. From this information, the system automatically identifies, through kilometre points, all structures affected by the selected route. Routes can vary in complexity: they can involve the entire motorway stretch, a limited section between two interchanges, or a single structure, as in the case of transit on a specific overpass. Once the relevant structures are identified, the software performs the structural checks required by the LG TE, providing a clear picture of the compatibility of the requested transit with the safety conditions of the infrastructure. In this way, the concessionaire has an objective and traceable tool to support the authorisation decision or any conditions. In addition to strictly structural aspects, the application also integrates geometric checks, essential for the safety of exceptional vehicle circulation. These include vertical clearance checks, carriageway width verification, curvature radius analysis, and assessment of the vehicle’s compatibility with the route geometry. The system can also take into account the presence of roadworks along the selected route, including possible interference with construction