Implementing a Drone Program

By Matt Hebdon, Alicia McConnell and John Zuleger, Contributing Authors

Implementing drones into a bridge inspection program is an exciting endeavor, and a strong foundation is critical for safe and effective missions. Successful integration requires a comprehensive understanding of safety, regulations, equipment, personnel and operations. 

The National Cooperative Highway Research Program (NCHRP) 12-122 project provides a holistic approach to using drones for bridge inspections and element-level data collection. The American Association of State Highway Transportation Officials (AASHTO) is expected to release subsequent guidelines, “Drone Applications for Bridge Inspections: Element-Level Bridge Data Collection,” which aims to help agencies incorporate drones into their inspection practices, this year.

But where should a drone program start? Where will it fit in an organizational structure, and what authority will the program have to operate safely and effectively? 

The first chapter of the proposed guidelines sets forth that organizations should identify which department will oversee drone operations and appoint a drone program manager with expertise in practical, supervisory and regulatory areas. The program manager’s role includes establishing the organizational structure, policies and effective management. 

Collaboration with Information Technology (IT), legal and safety teams is essential to integrate drones smoothly into existing operations. Policies and procedures must cover Federal Aviation Administration (FAA) Part 107 compliance, flight safety, emergency procedures, data management and post-processing. 

Effective program management involves remote pilot training, equipment maintenance, budgeting and continuous quality control, with internal improvements based on lessons learned in the field.

Drone Fleets and Equipment

Success depends on selecting the right drone and equipment. The third chapter of the proposed guidelines considers factors such as mission objectives, flight performance and security considerations, which are all key factors in the decision-making process.  

Drones come in various form factors (size, flight controls, sensors, payload capacity, etc.), but the most common families for inspection applications include single-operator with an integrated camera and dual-operator systems with options for interchangeable cameras or payloads. 

High-resolution cameras and mechanical zoom lenses are essential, while LiDAR, thermal sensors, and 3D modeling tools may aid in enhancing traditional inspections. Obstacle avoidance features and Real-Time Kinematics (RTK) technology can also be beneficial for in-flight safety, especially in environments with complex structural elements, turbulent airflow and GPS-denied environments. 

Other considerations include payload capacity, flight time, weather and wind resistance and security, particularly as it relates to cybersecurity and the legality of foreign-manufactured drones.

When selecting a drone, the following factors should be evaluated:

• Form Factor and Payload: Promotes and optimizes function, portability and size for mission goals.
• Flight Time and Range: Affects operational efficiency and the coverage area.
• Camera Resolution and Sensor Types: Impacts the quality of the inspection data and an inspector’s ability to determine defects during and after flight.
• Obstacle Avoidance: Determines the drone's proximity limits to structures and maneuverability in tight or congested spaces.
• Autonomous Capabilities: May enhance flight efficiency but should be used with caution to ensure data accuracy.

Remote Pilot-In-Command

A skilled and certified Remote Pilot-in-Command (RPIC) workforce is essential for a successful drone program and is outlined in the fourth chapter of the proposed guidelines. 

A comprehensive training pipeline, which includes FAA Part 107 certification and basic flight proficiency training, is necessary to ensure competence specific to bridge inspection applications. Basic flight proficiency should cover airspace regulations, evaluation of site conditions and obstacles, weather, navigation and emergency protocols. 

The hands-on portion should focus on practical piloting skills such as takeoffs, landings, maneuvers and emergency responses. Advanced training can include mission-specific topics like sensor operation, real-time data collection and advanced capabilities like autonomous or semi-autonomous flight.

Drone Inspection Operations

Drones are valuable tools for inspection operations across various industries, including infrastructure and public safety. They complement traditional inspection methods, helping inspectors access difficult-to-reach areas. 

Effective drone inspection programs recognize that the drone is a tool in the inspector’s toolbox that can be inserted in current access escalation (i.e. from the ground, ladder, lift, to rope access) and the fifth chapter of the proposed guidelines demonstrates various flight and collection techniques. 

The role of the drone is to assist in collecting data, but the inspector remains responsible for interpreting and verifying the findings. Inspections most commonly involve capturing high-resolution images or video that can also be supplemented with advanced methods such as 3D photogrammetric models or thermal scans. Standardizing data collection procedures ensures consistency and reliability.

Pre-Flight Mobilization

Before performing a bridge inspection with drones, it’s essential to evaluate site accessibility and address any potential risks, including congested or controlled airspace, remote pilot skill, obstacles and required permits. 

FAA authorization may be required for bridges that reside in controlled airspace. The choice of drone should depend on the structure type – generally speaking, smaller drones work well for conventional inspections, while larger drones are better suited for complex structures such as major river crossings.

On-Site Safety

Safety briefings should be held with on-site personnel to review workflow, logistics, site hazards and emergency protocols. Flight and/or inspection crews should define the inspection parameters, be mindful of traffic and traffic control limits and maintain situational awareness during flight. 

Remote pilots should be aware of potential hazards, such as trees, power lines, vegetation and wildlife interference. Pre-flight checklists, equipment logs, and daily inspections are essential for maintaining operational safety.

Detection Calibration

Before beginning inspections, conducting sensor tests at the site is crucial to account for changing lighting conditions and sensor performance. 

Inspectors should ensure that defects are detectable at varying distances and lighting. Image quality may differ between what’s observed during the flight and later analysis in native 4K format. 

Although technology like artificial intelligence (AI) can help analyze the findings after the flight, it is not commonly used to identify defects in real-time during the actual inspections of bridges.

Drone Accessibility to Structures

The RPIC should consider the type of drone that best suits the structure. Smaller drones are typically sufficient for conventional bridges, while larger, dual-controller drones are better suited for more complex structures to allow a dedicated RPIC to navigate while a second operator focuses on inspection. 

Flight and sensor capabilities directly affect defect detection. For example, elements like cables are accessible for 360-degree views, while intricate multi-girder systems may make navigation and accessibility for viewing defects more challenging. Closer flight proximity yields better inspection quality but may be less comfortable or unachievable for the RPIC.

Lighting conditions play a significant role in sensor performance, especially in confined spaces. To maintain adequate image quality, camera exposure adjustments may be necessary, though they can affect the clarity of recorded data. 

Drones with mechanical zoom lenses and integrated or detachable lights can aid in visibility, but such features may come with limitations, such as reduced image quality.

Inspections for Various Structures

• Decks and Substructures: Drones can effectively inspect monolithic bridge decks and substructures, often without needing to enter travel lanes. Higher-resolution cameras or zoom lenses may be necessary for more detailed inspections.
• Girders, Beams, and Bearings: Drones are effective at capturing data on these common structure types. Small drones with advanced obstacle avoidance systems can navigate between girders and bearings, though care should be taken to avoid turbulence and vortex shedding, which may pull the drone into the structure.
• Complex Bridges: Larger structures, such as trusses or cable-supported bridges, require skilled RPICs and may benefit from dual-controller workflows between the RPIC and sensor operator. These drones can fly at a slightly larger offset distance, reducing wind interference, and zoom lenses are useful for capturing detailed images and video of large spans.
• Tunnels and Culverts: GPS-denied environments like tunnels can benefit from advanced obstacle avoidance systems. Supplemental lighting, propellor guards and adjustable camera exposure can help ensure data quality in these environments.
• Channels and Scour: Automated missions are ideal for inspecting large areas like river channels. Pre-programmed flights can capture data to be processed into 3D models, providing insights into channel degradation and scour patterns.

Post-Flight Procedures

Post-flight data review is a necessary step for refining and analyzing collected data. Inspectors should analyze data in high resolution, as live video feeds into the controller are often of lower quality. 

3D models and AI analysis can help interpret data but should not replace human evaluation. Post-processing tools can enhance image quality, and AI may assist in detecting patterns, but inspectors should remain vigilant about phenomena like alarm fatigue and selective attention that can impair data review.

Data Management

Effective data management for storing, processing and reporting inspection findings can be cumbersome, especially with data set size increasing exponentially with high-resolution video recordings. 

The sixth chapter of the guidelines proposes a framework for implementing secure data storage systems, for immediate use (hot storage) and long-term access (cold storage). Security protocols should ensure that sensitive data is protected and compliance with regulations is maintained. 

The Skies Ahead

A program is only as good as its people, and no program should expect only to create policy doctrines and be successful. Program development should always incorporate experienced personnel providing hands-on training for managers and flight crews.  

Developing a comprehensive drone program requires strategic planning, investment in technology and a commitment to training and security. Organizations can unlock the full potential of drone technology by establishing a clear organizational structure, selecting appropriate equipment, training skilled flight crews, conducting safe and efficient inspection operations and implementing robust data management practices. 

Staying informed about regulatory changes and technological advancements will ensure sustained program success as drone applications evolve. Happy and safe flying! RB

Matt Hebdon is an associate professor at Utah State University. Alicia McConnell works at Rawlins Infra Consult as aerial, technologies advisor. John Zuleger is an infrastructure advisor at Rawlins Infra Consult.

The authors would like to recognize Jeff Sams, CBI, Rope Access Program Manager – Michael Baker Intl., and Ryan Stevens, Research Assistant – UT Austin for their contributions to the research and guidelines.