Image analysis for detecting the transverse profile of worn-out rails

Abstract

Over its useful life a railway track is subject to many mechanical and environmental stresses which gradually lead to its deterioration. Monitoring the wear condition of the railway superstructure is one of the key points to guarantee an adequate safety level of the railway transport system; in this field, the use of high-efficiency laser techniques has become consolidated and implemented in diagnostic trains (e.g. the “Archimede train” and the “Talete train” ) which allow to detect the track geometric parameters (gauge, alignment, longitudinal level, cross level, superelevation defect, etc.) and the state of rail wear (vertical, horizontal, 45-degree etc.) with very high accuracy. The objective of this paper is to describe a new nonconventional procedure for detecting the transverse profile of worn-out rails by means of image-processing technique. This methodological approach is based on the analysis of the information contained in high-resolution photographic images of rails and on specific algorithms which allow to obtain the exact geometric profile and the measurement of the relevant deviations compared to new rails of the same typology. The analyses and the first results, obtained from laboratory researches, concern rails cross sections taken from railway lines under upgrading. The procedure has shown high precision in the wear evaluation as well as great rapidity in being performed.