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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation
Winter 2018
Issue No:
Vol. 81 No. 4
Publication Number:
Table of Contents

Ready for Takeoff

by James Gray, Bryan Cawley, and Alicia Sindlinger

Unmanned aerial systems are taking flight in highway transportation. Here's a bird's-eye view at how and where the industry is using them.


The Federal Highway Administration and State agencies are exploring the best ways to incorporate small unmanned aircraft systems into their transportation toolbox. Here, a member of a flight crew contracted by FHWA checks the camera on a small drone prior to flight.


Demand on the Nation’s transportation network continues to rise. Over the next 30 years, the population of the United States is expected to increase by nearly 70 million people. Freight volume is likely to increase by more than 40 percent during that same timeframe. To continue to meet traveler expectations for a safe and reliable transportation system, transportation agencies are looking for better ways to safely collect more precise and timelier information. Unmanned aerial systems could serve in many capacities to help reach these goals and keep the country moving.

Using unmanned aerial systems in transportation applications can improve system performance, increase efficiency, and enhance safety by providing information from a different perspective. The method of collecting information using unmanned aerial systems is generally safer, less expensive, and less time consuming. For example, transportation agencies might use them for aerial photography to support surveying and bridge inspection efforts, which are two time-consuming and expensive tasks if done by traditional methods.

An unmanned aerial system includes an unmanned aerial vehicle, a system for data collection/communication, and a ground-based operator. More simply put, the system includes an unmanned aircraft and the equipment necessary for the safe and efficient operation of that aircraft with capabilities for data collection. An unmanned aircraft vehicle, often referred to as a drone, is defined by statute as an aircraft that is operated without the possibility of direct human intervention from within or on the aircraft (Public Law 112-95, Section 331(8)). Drones come in many shapes and sizes. Some come with single or multiple rotors and others come as fixed-wing designs.

Rapid technological advances are making unmanned aircraft more efficient and accurate, and more readily available and affordable. A variety of these aircraft are now available with lighter, longer lasting, more powerful batteries; longer flight times; larger payloads; and more sophisticated flight control software. Combined with advances in digital camera technologies, smaller remote sensing options, and new developments in computer software, the possibilities for building a system and meeting specific needs are immense.


This small unmanned aircraft, disassembled and stored in a box, is one that FHWA's Western Federal Lands Highway Division has tested. It is a basic, fixed mono-wing aircraft and has few moving parts.


The same drone, assembled and on the ground after landing.


According to the U.S. Department of Transportation’s Beyond Traffic 2045 final report, annual worldwide spending on unmanned aircraft is expected to double to $11.5 billion over the next decade. The ready availability of unmanned aircraft, along with their powerful capabilities and the technological advances, are fueling an increased interest in their use for a variety of purposes in highway transportation.

History of Drones: Birthed from Military Use

In the United States, infrastructure-related applications of unmanned aircraft gained popularity after their use became common in military operations, especially for intelligence, surveillance, and reconnaissance. Military uses started even before the 20th century began.

According to author Ian G.R. Shaw, “In 1896, Samuel P. Langley developed a range of steam-powered aerodromes, unpiloted aircraft that were flown successfully along the Potomac River near Washington,DC. In those ninety-second flights, a glimpse of the future could be seen in the hovering aerodrome.”

Aerial surveillance emerged as early as the 1898 Spanish–American War when the U.S. military fitted a camera to a kite, producing one of the first aerial reconnaissance photographs. However, it was not until the early 2000s in the combat zones of Iraq and Afghanistan that unmanned aircraft saw a significant increase in use. As of late 2004, unmanned aircraft had flown more than 100,000 flight hours in support of Operation Enduring Freedom and Operation Iraqi Freedom.

In fiscal year 2000, the U.S. Department of Defense’s (DOD) funding for drones was around $284 million (note this was before the terrorist attacks on September 11, 2001). Between 2002 and 2010, the U.S. military’s inventory of drones increased forty-fold to a fleet size of some 11,000 drones, hundreds of which are weaponized. In fiscal year 2017, the military allocated approximately $4.61 billion for drone-related spending.

According to DOD, unmanned aircraft have proven to enhance situational awareness, reduce human workload, improve mission performance, and minimize risk to both civilian and military personnel. All this is at a reduced cost compared to more traditional methods of conducting intelligence, surveillance, and reconnaissance. Because of these demonstrated benefits, DOD estimates that the prevalence and uses of unmanned systems will continue to grow at a dramatic pace.

Uses in Transportation

Unmanned aircraft have many potential uses in highway transportation—from inspection of construction and existing infrastructure assets to law enforcement and operations. According to a March 2016 survey by the American Association of State Highway and Transportation Officials (AASHTO), 33 State departments of transportation have or are exploring, researching, testing, or using this technology to inspect bridges and assist with clearing vehicle crashes, among other innovative applications. What follows is a closer look at how some States are using unmanned aircraft.


Minnesota Department of Transportation

The Minnesota Department of Transportation used this unmanned aircraft to test the drone's inspection capabilities on the Arcola Bridge near Crystal Bay, MN. Typically, this bridge is inspected using rope access because of its height.


Minnesota Department of Transportation

The drone proved to provide the level of detail needed to detect defects. In fact, the elements that are difficult to access through traditional methods were readily visible using the unmanned aircraft.


Minnesota Department of Transportation

The zoom lens on the drone's camera captured a high level of detail without having to position the unmanned aircraft too close to the bridge.


Construction. Drones can collect real-time environmental data (for example, air quality and temperature), survey difficult and inaccessible terrain, and track real-time construction progress. Imagery and data collected by unmanned aircraft have proven to be useful tools in design and preconstruction workflows and monitoring construction sites, among other uses.

In New York, the department of transportation reports an increase in contractors using unmanned aircraft for quantity calculations and routine construction monitoring, and to support model creation for automated machine grading.

Law enforcement and emergency response. Several law enforcement agencies are testing or using these systems at vehicle crash scenes.Using unmanned aircraft enables investigating officers to scan and document physical evidence, roadway dimensions, and characteristics more quickly than if they had to measure the evidence using traditional devices such as measurement wheels. They are able to clear crash scenes more quickly and restore normal traffic flow, resulting in fewer traffic delays related to crashes.

In Georgia, the Gwinnett County Police Department first used a drone in 2016 to investigate serious traffic crashes. The department began with two certified officers flying it over incident scenes to take pictures and video. The technology gives them a more complete view of the scene and saves time compared to waiting for a fire department ladder truck or using the police helicopter. The department hopes to have additional officers obtain their certifications and to extend its use of unmanned aircraft for other purposes.

Traveler information and data collection. Several types of traffic studies and research data acquisition efforts are well-suited for aerial surveillance by unmanned aircraft. A recent project by FHWA’s Office of Safety Research and Development used unmanned aircraft to collect data on lane choice and final destination for vehicles entering the study area. This particular application involved recording a 3-mile (4.8-kilometer) length of suburban freeway in Florida and three interchanges in Washington State. FHWA used unmanned aircraft systems to collect video from these areas to provide data for the analysis of driver behavior relative to lane selection along freeway segments between entrance and exit ramps. The technical results are available in the project report Enhancing Safety and Operations at Complex Interchanges with Integrated Signing, Marking, and Geometry.

Maintenance and infrastructure inspection. FHWA requests that States visually inspect and inventory all bridges on public roads with a span greater than 20 feet (6 meters) once every 2 years. These mandatory biennial bridge inspections are important for assessing the condition of bridges. However, some inspections require extensive climbing or equipment, which needs significant preparations and time to ensure safety. Using unmanned aircraft, bridge inspectors can gain supplemental information to support the condition assessment of critical elements of the bridge.

In 2015, the Minnesota Department of Transportation conducted a demonstration project using an unmanned aircraft for bridge inspection. The project team investigated use of the technology on four bridges located throughout Minnesota. The team evaluated the technology’s effectiveness as applied to bridge inspections based on field results. Overall, the study team observed that the safety risk to inspection personnel and the public is very low with the use of unmanned aircraft. The team also concluded that drones can provide a cost-effective way to obtain additional detailed information that otherwise might not be visible during routine inspections because of limited accessibility. For more information, visit

The Ohio Turnpike and Infrastructure Commission and Ohio Department of Transportation also are testing the use of drones to inspect bridges. In September 2016, the agencies demonstrated the technology on a turnpike bridge outside Fremont, OH. The demonstration showed how unmanned aircraft can supplement traditional inspection methods. For example, traditionally, inspectors sometimes climb the bridge using harnesses to visually access the underside of the bridge or require an under-bridge inspection truck parked on the outside lane or shoulder of the road with barrels set up to redirect traffic. If deterioration is identified using the unmanned aircraft, these traditional methods are then employed to get a hands-on inspection to verify the extent of the condition. The goal is to implement the technology throughout the State.


Washington State Department of Transportation

The Washington State Department of Transportation used a drone to capture video footage for this up-close view of a slope on State Route 503 that requires stabilization.


In Washington State, heavy rainfall in March 2017 caused a major debris slide onto a section of State Route 503 east of Woodland, WA, blocking the highway. The threat of additional falling rocks and debris prompted an emergency slope stabilization project. Geotechnical engineers with the Washington State Department of Transportation used unmanned aircraft to inspect the hillside and to help develop a permanent repair. Conditions were too dangerous to have the geotechnical engineers access the site themselves.

“We’re really just scratching the surface of the untapped ways we can use unmanned aircraft for transportation purposes,” says Hari Kalla, acting associate administrator for the Office of Planning, Environment, and Realty at FHWA. “Many States and disciplines are still exploring how and whether unmanned aircraft can help them achieve their goals.”

Challenges to Implementation

Successfully and safely using unmanned systems requires trained and skilled staff, as well as an understanding of the technology’s abilities and limitations, and its supporting information-gathering equipment. Effective use of the capabilities requires highly trained unmanned vehicle operators, sensor and payload operators, and analysts to process, analyze, and disseminate the data collected.

Although the technology is advancing at incredible rates, limitations still exist. For example, the duration of an infrastructure inspection can last from hours to weeks but existing drone batteries have a relatively short charge life and limit actual time of inspection to less than an hour.

Staff also must understand and operate the equipment within the regulatory boundaries of the National Airspace System, Federal Aviation Administration (FAA), and State and local laws. These complexities have challenged implementation by transportation agencies.

From 2014 through 2016, the National Conference of State Legislatures (NCSL) brought together State legislators, legislative staff, and private industry representatives to discuss unmanned aircraft systems. The group worked to develop policy issues and options related to the use of small drones for agriculture, insurance, natural resource management, law enforcement, and a variety of other purposes. Discussion focused on concerns about privacy, safety, and business and economic interests. In a white paper titled Taking Off: State Unmanned Aircraft Systems Policies, the group provided highlights of Federal actions and a comprehensive look at State legislative action addressing unmanned aircraft.

According to NCSL, beginning in the 2013 legislative session, State lawmakers considered many pieces of legislation addressing unmanned aircraft. As of July 2017, 40 States have enacted laws and an additional 3 States have adopted resolutions. Common issues addressed in the legislation include defining unmanned aircraft systems, unmanned aircraft vehicles, and drones; their uses by law enforcement and other State agencies; their use by the public; and regulations for their use.


A contracted flight crew for FHWA sets up survey controls for a 2016 drone test flight in Montana.


In 2016, the FAA finalized the first operational rules for routine commercial use of small unmanned aircraft systems (Title 14 CFR Part 107). The rule went into effect on August 29, 2016. The provisions aim to minimize risks to other aircraft as well as people and property on the ground. The regulations require pilots to keep unmanned aircraft within visual line of sight. Operations are allowed during daylight and during twilight if the drone has anticollision lights. The new regulations also address height and speed restrictions and other operational limits, such as the prohibition of flights over unprotected people on the ground who are not directly participating in the unmanned aircraft operation. In addition, the rule requires that the person actually flying a drone must be at least 16 years old and have a remote pilot certificate with a small unmanned aircraft rating, or be directly supervised by someone with such a certificate. For more information, visit

FHWA and Partners Evaluation of Drones

In 2013, FHWA’s Exploratory Advanced Research Program conducted a literature scan of research completed from 2006 to 2013 and focused on autonomous micro unmanned aerial vehicles for transportation applications. The scan provided background information to increase researchers’ knowledge and understanding of the topic, and contributed to the process of identifying priorities and opportunities for strategic investment in further research.

Currently, AASHTO is conducting a domestic scan of unmanned aircraft technology in highway construction and maintenance. Researchers are recording users’ initial investments, long-term and short-term plans for agency use of the technology, disposition of data collected, device performance in varying environmental conditions, and other practical assessments. The purpose is to visit the current adopters to document: (1) how they are using drones (for example, for inspection, inventory, survey, or other purpose); (2) why, how, and where they are using the technology; and (3) the way they are storing data.

The scan will improve understanding of the technology as well as benefits and the return on investment. The scan and its resulting report will help accelerate national deployment by demonstrating the technology’s usefulness and best practices. The scan also will provide information concerning where additional research and development are needed to support increased use of this technology.

In addition, FHWA’s Western Federal Lands Highway Division has built a strong business case for using unmanned aircraft as a more effective means to obtain critical topographic information used for many highway designs and to calculate material quantities. To make the business case for procuring the technology, FHWA started by identifying the data requested by the division’s design and construction customers, and then identifying the most appropriate means of gathering or developing that data. One of the major needs of the design phase is topographic data.Designers use topographic data to lay out the alignment, grade, and side slopes of the road project, and then to calculate construction quantities.

Currently, Federal Lands Highway (FLH) has three UX5-HP fixed-wing unmanned aircraft and a DJI Phantom 4 Pro, and several FLH employees have obtained their FAA pilot certificates.The FLH offices conducted test and production flights in 2017 and are now developing their policies and procedures for unmanned aircraft operations.

The Western Federal Lands Highway Division conducted a test project for using small unmanned aircraft during construction to relocate and reconstruct Pleasant Valley Road in Flathead County, MT. The project site is approximately 30 miles (48 kilometers) west of Kalispell, MT, in the Lost Trail National Wildlife Refuge. The division scheduled two flights for the project, one prior to construction in May 2016, and the second after construction in June 2017.

The division compared the data from the first flight (May 2016) to previous aerial light detection and ranging (LiDAR) data, and the results showed nearly identical accuracies. The division will use the additional data collected during the June 2017 flight to compare quantities calculated using the unmanned aircraft survey with those using typical survey procedures. If the results are within acceptable tolerances, the concept will prove valid, and the division may look at moving forward to develop its own unmanned fleet.


Software capabilities used for the FHWA tests include advanced mission planning and drone control during flight. This software-generated image shows the unmanned aircraft's flight path.


“I see so many potential uses for unmanned aircraft at the division,” says Bill McQuiston, senior highway designer and unmanned aircraft vehicle pilot/technician at the Western Federal Lands Highway Division. “The enthusiasm I am seeing for this type of advanced technology is contagious, and the possibilities unlimited.”

Reaching New Heights

Interest in using unmanned aircraft for transportation purposes goes well past the borders of the United States. The World Road Association-PIARC is also documenting international use of drones with a focus on low- and middle-income countries. A final report and presentation will be available on the World Road Association-PIARC’s Web site at

With no sign of interest in drones dissipating any time soon, FHWA continues to work to advance and define the role of unmanned aircraft in transportation applications. The agency has several activities currently in the planning stage related to market readiness. Activities include technical briefs that provide comprehensive guidance needed to assist transportation agencies and local governments in effectively using the technology; information-sharing workshops to disseminate hands-on knowledge, lessons learned, and best practices taught by champion States and subject matter experts; and a Web site to house all applicable information.

“The benefits of unmanned aerial systems far outnumber the challenges to implementation,” says Thomas Everett, associate administrator for the FHWA Office of Infrastructure. “We’ve seen what’s possible as testing has been underway across the country, and we’re looking forward to transportation agencies realizing the safety, time, and cost savings compared to using traditional practices for these transportation applications.”

James Gray is the preservation engineer and unmanned aerial systems specialist with the FHWA Office of Infrastructure. He joined FHWA in 2006 and has held multiple positions in FHWA’s Eastern Federal Lands Highway Division prior to his current position. He earned an M.B.A. from the Pennsylvania State University and a B.S. in civil engineering from Michigan State University. He is a licensed professional engineer in Michigan.

Bryan Cawley is the division administrator for the Wyoming FHWA Division Office. Since joining FHWA in 1997, he has held a variety of positions in multiple FHWA offices. He holds an M.B.A. from the University of Nebraska, an M.S. in construction engineering from Iowa State University, and a B.S. in civil engineering from the University of Utah. He is a licensed professional engineer in North Dakota.

Alicia Sindlinger is the associate editor of Public Roads.

For more information, contact James Gray at 517–702–1834 or