Subsurface Evaluation of Railway Track Using Ground Penetrating Radar

摘要

This report details the implementation of 2 GHz horn antennas for measuring working ballast thickness using ground penetrating radar and the initial implementation of a 500 MHz horn antenna used for subballast and subgrade characterization. The work was performed as part of the first task order and modification task 1 in the fourth phase of a multi-phase ground penetrating radar research and development project. During the course of the project, it was found that the 2 GHz horn antennas produced data that contain reflections from the void space in clean ballast. The amplitude of the void space reflections was found to be indicative of the degree of fouling. A simple data processing scheme was implemented that converted the reflection amplitudes to color bands, which were assigned to relative degrees of ballast fouling. The 2 GHz antennas were tested on five different tracks covering more than 382 mi and produced color-coded data that correlated well with available ballast condition ground truth. Subballast and subgrade layering to depths extending beyond 6 ft and anomalous high amplitude reflection events were successfully identified with the 500 MHz antenna.