Developments in GPR Based NDT for Ballastless Track of High-Speed Railways

For the past decades, ballastless track has been developed and used successfully throughout the world. Due to the multi-layer concrete structure of a ballastless track, timely detection of problems becomes a significant challenge. Ground Penetrating Radar (GPR), as an effective nondestructive method, has been applied to ballastless track in the last ten years. This paper reviews the state-of-the-art of GPR for the ballastless track. The challenges and problems are highlighted and discussed. A Vector Network Analyser (VNA) based stepped-frequency GPR system is considered for the problems and detection requirements. The experimental results show that the proposed system can detect narrow cracks in the depth up to 50cm.