UTU trains do not replace traditional track walks by track testing staff – although they do reduce the need for them. Instead, they direct the focus of track walks to areas needing inspection, saving time and money, and increasing the safety of the network.

TES staff undertake the role as an Ultrasonic Rail Flaw Detector Operator (URFDO) and operates a manual piece of rail flaw equipment, such as a B Scan stick (portable test process). The operator pushes a mobile test device over one rail individually or both rails simultaneously (at a walking pace) while visually interpreting test data on a monitor and ranking the flaw and reporting back to the relevant Rail Maintenance teams on the findings.

Typical service-induced discontinuities that occur in rail sections are head and web separation, horizontal split head, detail fracture, transverse fracture, engine burns, shelling, and bolt hole cracks. Head and web separations, as well as horizontal split heads, can be easily detected using a UT flaw detector with a 2.25 MHz / 0.50 in. straight beam transducer (such as our A106S) positioned over the rail centreline. By observing the returned signal, head and web separations can be confirmed through the loss of the back echo, which represents the reflection of the UT signal off the base of the rail.

Bolt-hole and transverse discontinuities are typically detected using 2.25 MHz / 0.50 in. angle beam transducers (such as the A540S paired with the ABSA-5T-X). Bolt-hole cracks tend to propagate at a 45-degree angle, making them particularly sensitive to detection when using a 45-degree angle beam transducer. Detecting transverse discontinuities and detail fractures, however, requires angle beam transducers with higher refraction angles (typically 60 to 80 degrees). Detectability improves for discontinuities that are angled downward in the same horizontal direction as the flow of heaviest traffic.