High-Sensitivity Vibration Monitoring of La Marota Viaduct Using a Novel 128-Channel Laser Radar System

In this study, we employed a novel system combining massively parallel FMCW Laser Radar and Laser Doppler Vibrometry to monitor and analyze the structural vibrations of La Marota Viaduct, as part of a multi-year structural health monitoring project for high-speed railway infrastructure near Almodóvar del Río in southern Spain. The system features 128 parallel channels capable of non-contact velocity and displacement measurements with 40 kHz sampling rate, allowing the real-time capture of dynamic structural behavior across a wide range of frequencies from a single installation point. The optical measurements were in good agreement with the numerical models and the accelerometer and strain gauge results. The exceptional sensitivity of the interferometry-based technique, particularly in low-frequency domains below 2 Hz, combined with the large number of measurement points offers the potential for superior model performance compared to traditional accelerometer setups. The high resolution and rapid acquisition capabilities of the system facilitated detailed analysis of the bridge's vibrational modes, providing insights into structural health and potential areas of concern.