Monitoring the dynamic displacements of railway track

Abstract

This paper reports the development and testing of two independent, innovative techniques for measuring rail displacements. One system combines remote video monitoring with particle image velocimetry, using a webcam and a small telescope. The second uses sleeper mounted geophones that give a voltage output proportional to the velocity of motion, which can be filtered and integrated to calculate displacements. Laboratory validation tests show that the video monitoring system can measure peak-to-peak displacements to within 0.04 mm from a distance of 15 m for frequencies less than 4 Hz. The geophones measure peak-to-peak displacements to within 0.07 mm for frequencies as low as 1 Hz. Data from three different standards of railway track and/or train speeds are used to explore and quantify the limitations of each system in the field.