The service in question concerns the execution of “urgent and indispensable works aimed at restoring the safety conditions of the Mongiove, Torretta, Calavà, Petraro, Rometta artificiale, Bonsignore, Malerba, Serra Inglese, and San Biagio tunnels on the A/20 Messina – Palermo highway, located on the Palermo-bound carriageway.”

The investigation activities included the preparation of “Inspection Evaluation Sheets,” georadar tests inside the tunnels, concrete sampling using a coring machine, sampling of reinforcement bars, assessment of the thickness of carbonated concrete layer, etc.

The field inspection and material investigations were carried out for the aforementioned tunnels between March and May 2021, and were divided into three phases: the first phase involved visual inspection, the second phase focused on georadar investigations, and the third phase involved the collection of concrete cores and steel bars.

The inspection and investigation activities were conducted either during regular traffic conditions, with the passing lane (left lane) initially closed and later the driving lane (right lane), or with the complete closure of the Palermo-bound carriageway. The visual inspection in the field was performed using the appropriate survey forms prepared by the DEC office, taking into account the guidelines of the 2020 Tunnel Inspection Manual and the New Defect Catalog of the MIMS (Ministry of Infrastructure and Sustainable Mobility).