Long-Term Monitoring for Track Slab in High-Speed Rail via Vision Sensing

Track slab deformation has become a challenging issue in high-speed rail (HSR) operation in recent years. This article proposed a novel approach for track slab deformation monitoring based on computer vision techniques. The basic principle of visual measurement of track slab displacement is first introduced. Then the detailed process of slab displacement calculation from the on-site images is presented, including region of interest (ROI) extraction, determination of the target edge, and displacement calculation. In this process, considering the actual operation environment of in-service HSR lines, an improved Canny algorithm, which can adaptively extract the location information of the target is proposed and employed in the image processing. Based on the modular design method, an online monitoring system for the displacement of the track slab is established. The devised system is installed on an in-service HSR line for long-term slab deformation monitoring. The performance of the proposed system is verified by one-year monitoring data of slab displacement. The measurement results of the proposed system are compared with an existing linear variable differential transformer (LVDT) system, demonstrating that it can accurately report track displacement with lower cost and easier instrumentation. This research is expected to provide insights to the railway maintenance-of-way department for better management and maintenance of slab deformation, especially under high temperature.