PSI - Issue 62

Ettore De La Grennelais et al. / Procedia Structural Integrity 62 (2024) 1089–1096 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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2. Preliminary considerations The management of tunnel safety is a crucial element in safeguarding and managing the road network, ensuring user safety, and preserving the durability of this particular type of structures. In this context, the framework agreement between the National Autonomous Roads Corporation (ANAS) and BOLINA Engineering plays a significant role, focusing its efforts on the road network in Northeastern Italy. The importance of this agreement lies in the need to adopt advanced practices in compliance with current regulations to ensure the safety of numerous tunnel which are part of the ANAS network. Guidelines provide a robust regulatory framework for bridge safety management, proposing a stratified approach tailored to the criticality of individual tunnels. In this context, BOLINA Engineering, a strategic partner of ANAS, actively engages in engineering activities across the first three levels of checks prescribed by the National Guidelines. The activity can be summarized as follows. • Level 0 (Lev.0): Tunnel inventory. The activity involves the preparation or updating (any existing records are made available to the operator) of inventory sheets as outlined in the Guidelines, adopting the corresponding formats. • Level 1 (Lev.1): Tunnel inspection, including all necessary auxiliary arrangements, such as site preparation and platform rentals. A close inspection of all structural elements, the road platform, non-structural elements, and systems must be conducted for each structure. For each inspected structure, the “initial inspection sheet” and “defect sheets” must be completed as per Level 1 of the Guidelines (Docume nt D). If the parts to be inspected are objectively impossible to reach even with special means or are shielded by various obstacles (covering elements of cladding, lighting claddings, electrical systems, etc.), the contractor must report the criticality and agree with ANAS representatives (DEC or DL) on the actions to be taken, which may include the removal of said obstacles. The contractor must also coordinate with ANAS technicians all necessary modifications to traffic regulations required for on-site inspection activities. • Level 2 (Lev.2): Determination of the attention class according to the Guidelines based on the information obtained in previous levels and according to the severity judgment of identified defects. The Attention Class value is identified, with expert and specialized judgment, through Level 0 and Level 1 inspections. The determination of the Attention Class must include the study, analysis, and procedure for determining primary and secondary parameters, factors (hazard, exposure, and vulnerability), and hence the Attention Class, which must be performed using a “class and logical operators” approach, grouping each primary and secondary parameter into classes and combining the classes through logical flows. The Attention Class must be evaluated for the following areas: – Overall and geotechnical “global” structural Attention Class; – “Local” structural Attention Class; – Seismic Attention Class; – Road Attention Class; – Geological Attention Class associated with landslide risk; – Hydraulic Attention Class. The combination of Attention Classes results in a qualified overall Attention Class determined by a diffusion index obtained by applying appropriate combination matrices as outlined in the Guidelines. Additional specific activities are planned: – Geometric and defect surveys carried out based on precision photogrammetry and the generation of georeferenced point clouds on the basis of which physical models supporting the assessment of any evolutions over time of identified defect scenarios will be generated; – Possible installation of structural monitoring systems.