Recent developments and ongoing challenges in the implementation of UAS assisted bridge inspections

Abstract

In the past decade, the use of drones, or unmanned aircraft systems (UAS), to supplement engineering activities such as structural inspections has increased considerably due to the advances in the associated technology in terms of UAS positioning, operation, control, and payload capacity. High-resolution imagery of structures obtained using drones fitted with digital cameras can be post-processed using computer vision and photogrammetry techniques to potentially provide more reliable structure geometry and inventory, structure condition, and structural performance (SHM) data, in less time and possibly at a lower cost than current methods. This approach can aid Principal Inspections for bridge structures, particularly where access is difficult, obviating the need for expensive under-bridge equipment and/or lane closures. However, challenges remain for the widespread implementation of drones for bridge inspections, primarily relating to measurement accuracy and stabilisation of images recorded during drone flight, while issues around safety and regulation can also limit UAS operation for this purpose. This paper presents a brief overview of these challenges and investigates the use of computer vision and photogrammetry techniques for measurement and defect detection in bridge elements. This is carried out via the processing of images of concrete bridge elements obtained using low-cost drones.