Monitoring rail track bolt loosening using fiber-optic distributed acoustic sensing

Bolt loosening in railway tracks poses considerable safety and operational risks, such as track misalignment, wear and tear, maintenance challenges, and operational disruptions. This study explores the use of acoustic signals from wheel-rail interactions to detect bolt loosening. Specifically, it demonstrates capability of optical fiber distributed acoustic sensing (DAS) technology for monitoring or detecting bolt loosening on a rail track sample. The research includes a fundamental analysis of different test scenarios and a performance comparison between two types of optical fiber sensing cables used in this application. Implementing this advanced technology would enable railway operators to perform real-time monitoring, reducing the need for labour-intensive manual inspections and minimizing disruptions to train operations.