“…Compared to the conventional ballast track, the ballastless track has the advantages of high structural stability, good stiffness uniformity, long service life, and less maintenance work [2,3]. Nevertheless, the complex natural environment, rain erosion, train load, and thermal load may lead to the ballastless track bearing some structural diseases, such as cracks, air voids, and delaminations [4,5,6]. These diseases may not be easily recognized by visual investigation.…”