PSI - Issue 84

N. Kheirkhahan et al. / Procedia Structural Integrity 84 (2026) 33–40 N. Kheirkhahan et al./ Structural Integrity Procedia 00 (2026) 000–000

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Fig. 3. Distribution of relative global efficiency loses in sub-networks, categorized by buffer radii, around the removed edge for road types.

4.3. Criticality score The study uses the Augmented Link (A-link) framework developed by Postorino and Sarnè, 2025 to assess the resilience of Messina road network. The method integrates endogenous network properties with multi-hazard assessment into a single link-level score. Failure scenarios are simulated using percolation theory, where edges are sequentially removed to induce network resilience (Artime et al., 2024; Dong et al., 2020). For each edge, the criticality score is the product between the normalized global efficiency loss (range 0–1) within fixed buffer radii and the discrete multi-hazard value (range 0–3), identifying links whose failure most disrupts connectivity. Fig. 4 shows the resulting spatial distribution of link criticality across all buffers.

Fig. 4. Criticality of all edges under multi-hazard exposure: Scatter plots display normalized global efficiency loss versus hazard scores for six buffer radii. Each dot represents an edge, with color indicating the combined criticality score from hazard intensity and global efficiency loss. While the same ten edges consistently appear among the top-ranked, their order varies slightly across buffer radii, reflecting the buffer’s influence on criticality scores. Notably, segments on the national road SS113 Settentrionale Sicula (ID 148) and the provincial road SP43bis Strada Panoramica dello Stretto (ID 3757), both primary roads, consistently rank highest, indicating that primary roads exposed to high multi-hazard risks represent the key vulnerabilities in the Messina network. 5. Discussion This study evaluates the baseline resilience of Messina road network using percolation theory to simulate worst case disruptions. By removing edges, it identifies the critical links that preserve network connectivity. The results of the global efficiency loss within buffers show that motorway road removal consistently causes the most considerable global efficiency losses across all buffer radii, suggesting that it poses the greatest risk to overall network performance. Primary and secondary roads also maintain high criticality, while extreme losses are concentrated among higher-order roads. The A-link approach calculates a hybrid criticality score for each edge by integrating endogenous and exogenous features with single- and multi-hazard indicators across four single-hazard and one multi-hazard scenario, providing a comprehensive assessment of road vulnerability under multiple hazards. Because earthquake hazard values are nearly uniform (value of 2), criticality in this case depends primarily on global efficiency losses. In contrast, tsunami, flood, and landslide hazards exhibit combined effects, with their most critical segments occurring where both hazard values and global efficiency losses are highest. The analysis further identifies