Drone-Assisted Structural Assessment of Medieval Masonry Arch Bridges: Innovative Methodologies for Heritage Conservation and Damage Diagnostics

Abstract

This research investigates the applicability and efficiency of Remotely Piloted Aircraft Systems (RPAS) in conducting detailed structural inspections of medieval masonry arch bridges, evaluating their capacity to supplant conventional assessment methods. Through case studies on two historically significant pedestrian bridges—Grajal Bridge (monoarch) and Brandomil Bridge (multiarch)—located in Spain, visual inspections were executed via multirotor drones equipped with high-resolution imaging systems. The drones enabled comprehensive diagnostic analyses of structural pathologies, including efflorescence, biological colonization, black crust formation, and material alveolization, particularly in otherwise inaccessible intrados and foundation elements. Results validate the deployment of RPAS as a sustainable, safe, and cost-efficient tool, mitigating occupational hazards and minimizing intervention invasiveness while preserving the architectural integrity of heritage assets. This work demonstrates the transformative potential of drone technology in preventive conservation protocols, structural health monitoring, and longitudinal documentation of vulnerable historic infrastructures.