Long-Term Monitoring of Small Displacements of Infrastructures with a Low-Cost GNSS Device

The monitoring of large infrastructures such as bridges, dams, and Tailings Storage Facilities (TSFs) is critical for ensuring structural safety and preventing catastrophic failures. Traditional geodetic monitoring approaches, while accurate, are often labour-intensive, expensive, and impractical for large-scale or remote deployments. This study evaluates the capability of dual-frequency low-cost GNSS receivers (ublox ZED-F9R) integrated with a minicomputer to measure millimeter-scale movements over extended monitoring periods. Two measurement campaigns are conducted: a 16-hour short-term test and a 60-day long-term deployment. A rigid aluminium beam with photogrammetrically measured baseline served as ground truth for assessing positioning accuracy. Short-term experiments demonstrated sub-millimeter accuracy while the 60-day campaign achieved 3D baseline measurement accuracy and precision below 2 mm despite significant environmental variations. The results confirm that low-cost dual-frequency GNSS systems can reliably detect centimeter/year-level deformations, making them suitable for monitoring slow-moving processes in critical infrastructure. The collected data, including raw GNSS observations, processed coordinates, and meteorological data, is publicly available for research purposes at https://doi.org/10.5281/zenodo.17378723.