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The Institute of Space and Earth Information Science (ISEIS) of The Chinese University of Hong Kong (CUHK) and the German Aerospace Centre (DLR) jointly hosted the International Workshop on InSAR (Interferometric Synthetic Aperture Radar) Technologies for Urban Infrastructural Health Diagnosis recently.  In the workshop, the most innovative research on InSAR technologies for urban infrastructural health diagnosis was presented and the key challenges were discussed.  Prof. Hui Lin, Director of CUHK ISEIS and Prof. Richard Bamler, Director of the Remote Sensing Technology Institute, DLR co-chaired the workshop attended by nearly one hundred scholars and research students from mainland China, Germany, Italy, England, the Netherlands, Pakistan, the Philippines, and Sri Lanka. 

Civil infrastructures, including airports, roads, railways, pipelines and bridges, are the urban lifeline.  Under progressive natural and/or man-made stressors, slow ground subsidence and infrastructural deformation have become potential geo-hazards that threaten economic sustainability and human well-being. 　For instance, the sinkhole subsidence which occurred in November 2016 in Fukuoka, Japan, was probably caused by nearby tunneling works. 　Ground subsidence has caused large economic loss including more than one hundred billion RMB in the Pearl River Delta region alone. 

Prof Hui Lin remarked, ‘Due to the large volume, wide coverage, high utilization rate and complexities of the urban infrastructure, conventional monitoring approaches have failed to guarantee accuracy and timeliness.  Over the past decade, the international community has focused on satellite remote sensing for rapid urban infrastructure health diagnosis.  A number of countries have launched high-resolution radar remote sensing satellites, while many research institutions have put more resources into relative data processing software development to enhance the application of engineering to the technology.  These advances have shed light on a health diagnosis of urban infrastructure.’ 

Satellite-based InSAR technologies have the unique capability of monitoring spatially large-scale and temporally long-term movements of land surfaces.  As a remote sensing technology, this has some distinct advantages over conventional engineering methods, namely, (i) large scale monitoring capacity; (ii) high spatial density of measurements; and (iii) cost-effectiveness with no need for any instruments on structures, so providing an excellent solution for infrastructural health monitoring.  With the gradual maturity of InSAR technologies, it is time to use it as an operational tool for urban infrastructural health diagnosis.  In the workshop, it was suggested that international standards should be established in order to strengthen the relationships of international InSAR communities. 

InSAR is a key research area of ISEIS at CUHK.  To promote the development of InSAR technologies, ISEIS has hosted the InSAR training courses since 1998, carried out the ground settlement monitoring since 2002, and hosted the first international workshop on InSAR technologies for large man-made linear feature stability surveillance together with DLR in 2012.  In this workshop, the international community gave high praise to the contributions to InSAR technologies made by ISEIS, including the establishment of a ground satellite receiving station, the development of Skysense, the first Chinese commercial InSAR software, the InSAR experiments on airports, railways, highways and buildings, as well as its experience in cultivating many high-level research students and scholars.