Bridge Vertical Deformation Monitoring Using GBSAR Repeat-Pass Observations

Document Type : Original Article


School of Surveying and Geospatial Engineering, College of Engineering, University of Tehran, Tehran, Iran



This study presents the feasibility and performance evaluation of a developed ground-based synthetic aperture radar (GBSAR) system for monitoring vertical displacement in bridge structures. Bridges, as critical transportation infrastructures, require regular assessment to ensure safety. In recent years, ground-based radar and synthetic aperture radar (SAR) systems have demonstrated their effectiveness as non-contact displacement monitoring tools for structural displacement monitoring. This study utilizes a prototype GBSAR system consisting of a W-band radar, TI-AWR1642BOOST, with a maximum signal bandwidth of 4 GHz, incorporated with a 15 cm horizontal mechanical rail to enhance cross-range resolution. To evaluate the performance of the GBSAR, two types of experiments were conducted: laboratory experiments in a controlled situation and outdoor simulations by creating a light-weight bridge and inducing displacements through the addition or removal of loads on its surface. The results obtained from the laboratory experiments showcased a measurement accuracy ranging from 50 to 80 micrometers in vertical displacement, while the results from the simulated bridge showed a final accumulated vertical displacement error below 1 mm. These overall results validate the applicability of the developed GBSAR system for vertical displacement monitoring of structures with sub-millimeter accuracy.


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