RECENT DEVELOPMENTS IN ULTRASONIC TECHNIQUES FOR RAIL-TRACK INSPECTION

Abstract

Abstract With the rapid increase in the speed and density of global rail traffic, there is growing demand by governments and the rail industry for reliable and automated rail track inspection systems. This paper presents a brief overview of recent advances in ultrasonic non-destructive testing technologies that may be applied to rail track inspection. These techniques are described and their relative merits and drawbacks are highlighted and compared. The comparison indicates that no single ultrasonic technique can be used alone for comprehensive rail track inspection, and the combination of two or more techniques is required to achieve the required levels of accuracy and reliability. 1. Introduction In the last few years, there has been tragic loss of life in train derailment accidents across Europe. A major cause of train derailments is defects within the rail track, which may lead to breakage of the track under the stress of a high-speed train. Most of these accidents could have been prevented by better track inspection and maintenance. Track is currently inspected manually, and is highly subject to human error; furthermore, data is generally not collected and logged, making quality control and post-processing impossible. The recent trend is to partially or fully automate the inspection process, which could potentially save human life, money and time. Ultrasonic techniques are still the most popular non-destructive testing methods applied to problems such as the inspection of rail track. Sometimes defects cannot be detected because of the contamination of the rail surface (dirt, shelled rails etc.), which is referred to as “the blind spot problem”. Also, sometimes the rail track is considered “untestable” because of the presence of large shallow subsurface cracks which preventing the ultrasonic beams from passing through the remaining section of the rail