Transforming Tunnel Lining Inspection Using Novel Non-Destructive Testing Approach

This project downselected and validated an advanced image-based Non-Destructive Testing (NDT) methodology for inspecting metallic-clad concrete road tunnel linings in National Highways infrastructure. X-ray Backscatter (XBS) was identified as the optimal solution for detecting surface defects in the concrete tunnel lining through the steel cladding. The study evaluated various handheld XBS systems, and their performances were assessed through a series of controlled workshop-based trials on a representative concrete artefact with artificially created surface defects, followed by field validation trials on a live tunnel asset. The imaging performance of these XBS systems was quantitatively evaluated. While not a substitute for cladding removal, the trialled methodology demonstrated encouraging potential as a complementary tool to support tunnel maintenance efficiency. Initial results indicate it may provide useful quantitative data to inform maintenance decisions; however, these findings remain preliminary. Further refinement and validation are required to establish its reliability and consistency. Current research is focused on automating the deployment process, which is presently manual, with longer-term efforts exploring AI-based analysis to support future scalability and efficiency.