PSI - Issue 84

E. Renzi et al. / Procedia Structural Integrity 84 (2026) 1361–1368 E. Renzi et al. / Structural Integrity Procedia 00 (2026) 000–000

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• Rationalization of the data to be collected in the descriptive inspection form , through the separation into a section of “fixed data”, which do not change over time, derived from the Inventory Form or to be compiled during the first inspection of the structure, and a section of “variable data”, to be updated over time during the periodic inspections of the structure. Other supplementary annexes concern some defectiveness forms to be used during Level 1 inspections, which have been detailed by introducing integrations that make compilation more effective and clearer. In this case too, the data already collected with previous forms remain fully compatible and interoperable, without changes to the parameters or evaluation methodology. Specific fields and forms have also been introduced for structural elements and components previously not explicitly addressed, for which forms related to other elements had to be adapted. 1.2. Specifics about special inspections An important contribution of the new operational instructions concerns special inspections for post-tensioned precast concrete bridges and bridges in areas with evidence of flooding, erosional, and landslide phenomena, or recognized as high hydrogeological risk, with evidence of possible interference with the structure, as per paragraph 4.3 of the Guidelines. To support the execution of the special inspections provided for post-tensioned bridges, the corresponding data collection form, already present in the 2022 Guidelines in Annex D (MIMS, 2022), has been expanded and detailed in Annex D bis: Annex_D_Bis_Special_Inspection_Form_Post-Tensioned_Cable_Bridges_1 (CSLLPP, 2025). Regarding bridges in areas with evidence of flooding, erosional, and landslide phenomena, or recognized as high hydrogeological risk with evidence of possible interference with the structure, in the absence of specific indications in the 2022 Guidelines and Operational Instructions, the new Operational Instructions provide some additional annexes: Annex D bis, E, F and G (CSLLPP, 2025), containing templates and procedures that can be taken as useful references and that will be referenced in the following paragraphs. The new Operating Instructions 3.6.2bis, 3.6.3bis, 5.4 and 5.5 introduce the possibility to carry out a Level 3 assessment (VAL 3), which has a simplified nature and is less burdensome than Level L4 assessment (VAL 4), specifying the procedures that can be adopted (in fact, the hydraulic VAL 3 was not explicitly provided either in the Bridge Guidelines or in the 2022 Operating Instructions). Two cases are envisaged for applying this assessment: following a special inspection; following a L2 hydraulic assessment with a High or Medium-High Warning Class output. In other words, a preliminary level of in-depth analysis is foreseen, to be carried out based on more accurate knowledge and with probabilistic analysis of hydrological–hydraulic events, defining the levels as a function of return periods, even without performing the accurate structural assessment (VAL 4). This VAL3 assessment allows to determine whether it is necessary to proceed with monitoring, with a VAL 4 assessment of the bridge, or whether the structure falls back into the cycle of periodic inspections and assessments, performing a new assignment of the Warning Class by modified criteria. The supplementary Annex E ( Annex E – Special Hydraulic Inspection Indicators Form ) is a form dedicated to Hydraulic Special Inspection Indicators to improve data collection and specify when special inspections are required (§ 3.6 IG). The Hydraulic Special Inspection Indicators are: • Evidence of inadequate hydraulic freeboard (accumulation of floating debris on the structure; high-water marks on piers or abutments; flood traces on adjacent land; signs of impacts on the deck). • Evidence of erosive phenomena (visible scour at piers or abutments; foundations permanently below water level; evidence of damage to foundation protection works or to channel-bed stabilization works such as check dams/sills). • Other critical issues (evidence of damage to bank-stabilization works; bank erosion; tendency of the riverbed to wander/meander). The supplementary Annex F ( Annex F - Special Inspections and Level 3 Preliminary Assessment for Hydraulic Risk ) defines the procedures for in-depth hydraulic assessment in areas subject to flood/erosion risk, addresses further 1.3. Improvement of hydraulic inspection and monitoring procedures