Influence of Varying Operational Parameters on the Defect Detection Performance of a High-Speed Ultrasonic Rail Inspection System During Field Tests

Abstract

Abstract Background Continuous monitoring is essential for detecting internal defects in rails and prevent derailment related accidents. Existing techniques do not facilitate continuous monitoring because they require specialized test cars and can only operate at speeds of up to 30 mph. Objective The objective of this study is to evaluate the performance of a high-speed rail inspection system using a non-contact ultrasonic technique with the potential of operating at train revenue speeds. Methods The technique utilizes air-coupled transducers that record the ultrasonic guided waves generated by the rail-wheel contact and does not require a controlled acoustic source of excitation. A modified version of the traditional Welch’s periodogram technique is utilized to extract the Green’s function between two points on the rail. The passively extracted Green’s function is then analysed statistically to detect structural discontinuities (e.g., defects) in the rail. Results Results from fields tests performed at the Transportation Technology Centre (TTC) in Pueblo, CO, USA, demonstrate possible test speeds as high as 80 mph. From these field tests, the performance of the system is evaluated using Receiver Operating Characteristic (ROC) curves for a range of different operational parameters including test speed, location of the sensors relative to the locomotive (source), signal-to-noise ratio (SNR) of the raw signals, SNR of the reconstructed transfer function, baseline distribution length in the statistical analysis, wheel-rail interactions, and redundancies introduced from multiple runs over the same track. Conclusions This study presents the current stage of development and performance of the passive rail inspection system with full-scale experiments under field conditions. The results indicate the potential of the system to operate at high speeds as well as possible avenues of future improvement to the system.