A Critical Analysis Based on the Comparison Between Traditional and Advanced Approaches to the Visual Inspection of Bridges and Viaducts

Infrastructure management and maintenance is often based on visual inspections. This approach is prone to human error and influenced by inspector perception. Certain elements of infrastructures can be inaccessible to visual inspection and the use of drones to capture high-quality pictures of the structures is often helpful. This paper presents a comparison between evaluations of the same structures by two different teams of inspectors with comparable experience and preparation. The first inspection was performed in-situ using a traditional approach, aided by drones only for those elements that were impossible to reach. The second inspection used pre-recorded videos and pictures taken by drones, without the team of evaluators ever seeing the structure in person. For each structure, based on the data obtained from the inspections, both teams filled the same damage chart recording various types of damage on different materials. With the aim of exploring the effectiveness of inspections based on pre-recorded drone data, advantages and criticalities found on the field are presented with reference to several case studies. Based on this critical analysis, suggestions are proposed on how to optimize drone-assisted and drone-based inspections.