Guided Wave Inspection and Monitoring of Railway Track

Cost-effective NDE of the vast length of aging railway track around the world remains a challenge for the community. Continuously welded rail is installed in tension but temperature changes can result in rail buckling if the initial tension is insufficient or fatigue cracks and ultimately rail breaks if the initial tension is excessive. The NDE challenge therefore includes both the detection of defects and the measurement of axial stress. Since continuously welded railway lines may be thought of as one-dimensional elastic waveguides, they are natural candidates for guided wave ultrasound, which offers the potential to interrogate a large length of rail from a single position. Guided waves have been proposed as a means of detecting the axial stress in rails to prevent buckling and also as a means of detecting complete breakage and cracks prior to breakage. This paper reviews the approaches used and the modeling methods available to support the development of nondestructive inspection and monitoring systems. Possibilities for future systems are also discussed.