Monitoring and early-warning technique for expressway substructure defect detection based on ultra-weak FBG array sensors

The aging of expressway pavements poses a significant threat to safety and functionality, particularly exacerbated by extreme climate events. Real-time, non-intrusive detection technologies are essential for identifying concealed defects before accidents occur. In this work, an Ultra-Weak Fiber Bragg Grating (UWFBG) array system is used to detect road defects without disrupting traffic. Field tests for voids beneath the pavement show that the UWFBG system can accurately locate subgrade voids using intensity-based waveforms. Frequency analysis provides additional details on concealed defects. This method supplies a transformative solution to early warning of subsurface issues, significantly improving expressway safety and intelligent management level for the ultrahigh-throughput traffic network.