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Monitoring structure health of urban bridges with advanced multi-temporal InSAR analysis

ABSTRACT Acting as economic lifelines, bridges are essential infrastructure elements in China. The continuous monitoring of their stability therefore is of utmost significance to prevent the public death and injures resulting from bridge collapses. Typically, the deformation of bridges is detected by traditional on-structure surveying methods which are limited by the sparse measurements and large consumption of time and manpower. Thanks to the availability of numerous archived high-resolution spaceborne synthetic aperture radar (SAR) images coupled with the technology development of multi-temporal interferometry SAR, currently, millimetre level of subtle deformation monitoring and health diagnosis on bridges through the estimation of subsidence velocities using time-series SAR images has become a precise and cost-effective solution, assisting the conventional measures for bridges monitoring. Due to the fine level of detail information in X-band SAR images, the identification of even smaller bridges is possible. In this article, the special appearance of bridges over water in TerraSAR-X Stripmap images is discussed based on the backscattering mechanism analysis. Besides, an advanced high-resolution multi-temporal SAR Interferometry processing and analysis approach to enhance the capabilities for bridge health monitoring is illustrated based on the case study of Lupu Bridge in Shanghai, before discussing the existing challenges and future developments associated with bridge-specific deformation surveillance.