## 4 Discussion  
The integrated use of PS-InSAR monitoring with traditional geotechnical data allows for enhanced decision-making regarding maintenance prioritization, emergency response planning, and resource allocation for high-speed railway operations [22]. The early identification of high-risk zones supports preventive reinforcement strategies, such as grouting, drainage improvement, and subgrade stabilization, thereby ensuring continued safe operation and reducing the potential for service disruptions.  
The application of PS-InSAR techniques for monitoring ground deformation along the Honam High-Speed Railway has clearly demonstrated the effectiveness of satellite-based remote sensing in identifying both spatial and temporal patterns of settlement in complex geotechnical environments. Compared with traditional monitoring methods, such as leveling and GNSS surveys, PS-InSAR provides broad coverage and high temporal resolution, enabling the continuous observation of subtle displacements over extended areas [15; 19]. This study's results corroborate the findings of previous research, which emphasized the advantages of PS-InSAR in infrastructure monitoring, particularly in areas affected by long-term subsidence and soft ground conditions [21].  
The spatial distribution of subsidence observed in this study aligns with the known geotechnical conditions of the railway corridor, where thick alluvial deposits and high  
Figure 8: Deformation at the corner reflector site based on the PS-InSAR and leveling survey results.  
groundwater levels contribute to ongoing consolidation settlement. The identification of critical subsidence zones between chainage 67 km and 82 km underscores the need for targeted ground improvement and reinforcement strategies. Moreover, temporal displacement trends revealed seasonal fluctuations, with acceleration during wet periods and deceleration during dry seasons, which can be attributed to fluctuations in pore water pressure and the soil moisture content.  
A key finding of this research is the strong correlation between PS-InSAR-derived displacements and ground-based measurements, such as leveling and corner reflector data, with R\({}^{2}\) values exceeding 0.93. This high degree of consistency validates the use of PS-InSAR as a reliable tool for long-term monitoring and confirms its potential for integration into railway maintenance and safety management systems. Furthermore, the ability to detect accelerating settlement trends before they exceed critical thresholds presents opportunities for predictive maintenance, reducing the likelihood of costly emergency repairs or operational disruptions. Moreover, combining PS-InSAR monitoring with conventional geotechnical data enables enhanced decision-making for maintenance prioritization, emergency responses, and efficient resource allocation in high-speed railway operations [22]. The early identification of vulnerable zones further supports preemptive reinforcement measures, such as grouting, drainage improvement, and subgrade stabilization, helping to mitigate risks and maintain continuous safe operation.  
Despite these advantages, certain limitations must be considered. PS-InSAR performance can be affected by vegetation cover, atmospheric artifacts, and geometric decorrelation, especially in areas with rapid land cover changes or complex topography [16, 18]. Therefore, the integration of PS-InSAR with other geotechnical data and field surveys remains essential to ensure comprehensive risk assessments and the design of effective mitigation measures.  
The implications of this study are substantial for high-speed railway infrastructure management. By establishing a PS-InSAR-based monitoring system, railway operators can efficiently identify high-risk sections, plan maintenance interventions, and allocate resources strategically. This approach supports a shift from reactive to preventive maintenance strategies, enhancing safety, extending the infrastructure lifespan, and minimizing operational downtime.