Implementation of Multitemporal Synthetic Aperture Radar for Ground Hazard Risk Monitoring on Railway Right of Way

Railway transportation has been the backbone of national economies worldwide. When geohazards occur and damage the network, they affect railway operations, resulting in delays and detrimental social and economic effects. A potential tool for monitoring the vast network for geohazards is satellite-based radars. Interferometric synthetic aperture radar (InSAR) may be used to study a wide range of geophysical phenomena. Its ability to study geohazards is frequently constrained by several challenges stemming from adverse atmospheric effects and wave scattering associated with site conditions and terrain characteristics. The authors have developed the framework of a monitoring system that uses satellite radar imagery analysis for identifying geohazard-prone locations through continuous monitoring of large regions. This paper discusses one implementation of multitemporal InSAR techniques that includes the new concept of a “Rolling SAR Image Stack.” In addition, it introduces three postprocessing techniques that enable the detection of critical locations where geohazard failures may initiate along the railway right of way before an event takes place. A site characterization and classification guide is introduced to facilitate the selection of the most effective SAR analysis method for monitoring the area of interest. The guide considers on-site conditions affecting the quality and availability of radar data. This paper summarizes the investigations, methodologies, and approaches that led to the development of the workflow of the proposed monitoring system and demonstrates the ability of the proposed monitoring framework to identify critical locations of geohazard failure potential through implementation case studies.