Glued-Laminated Timber Arch Bridge Inspection Using UAV

The use of unmanned aerial vehicles (UAV) are gaining popularity for bridge inspection due to its capabilities to efficiently reach an inaccessible place, collect imagery, and identify damage. Bridges inspected manually are found to be time consuming, and involve safety risks for the inspector on hard-to-reach places. Therefore, it is necessary to advance the current bridge inspection technology using UAV. The main goal of the paper is to inspect different types of damage of an in-service glued-laminated arch bridge with concrete decking using a commercially available UAV and evaluate the UAV's ability for collection good quality bridge inspection data. As part of the inspection, the arch timber stringer bridge located near city of Keystone in the state of South Dakota was selected. Preliminary inspection was performed over the bridge to identify major damage locations using UAV, and then a detailed inspection was conducted for damage specific to the bridge components such as stringers, abutments, and underneath deck. High-quality digital images on the components with different degrees of damage/deterioration were captured using UAV. Then, these images were used to identify the types of damage on each component: cracks on concrete abutment, exposed rebar and efflorescence on concrete deck, and checks and stains on glulam stringers. The damage identified by UAV was compared to those from the inspection report completed by South Dakota Department of Transportation (SDDOT). Key findings showed that the UAV-enabled inspection efficiently discovered detailed damage for individual bridge components, and provided results almost identical to those gained from the inspection report.