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Waving Goodbye to Flaggers – Exploring Alternative Traffic Control Devices

The Issue:

When performing two-lane road maintenance, what is the best way to control traffic for periods ranging from a few hours to a few weeks?

The Research:

Exploring Alternatives of Traffic Control Devices

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Flaggers direct traffic during maintenance sessions on two-lane roads.  The goal of this research was to find out whether the automated flagger devices that are used in some other states would help the Ohio DOT. In relation to this, the research investigated issues surrounding flagger devices’ safety, cost, staffing, and quality of traffic control.

Projects in this research were set in specific times and locations, and the team analyzed three different methods. The first method involved small roadside automated flagger devices with stop gates, the next method used standard-sized portable traffic signals, and the last method used standard human flaggers. The success of each method was determined by the number of cars that went through a red light or around a flagger after being told to stop.

Success rates were about the same for the flaggers and the small automated flagger devices. A key problem with the full-sized traffic signals was that the motorists who were already queuing did not always obey the red light, but sometimes simply followed the vehicles ahead of them. Because of this, the operation of these signals should be such that the entire vehicle queue can clear within one cycle.


After analyzing the results of the field tests, the costs versus benefits, and the motorists’ reactions, the recommendations are as follows. First, the research recommends using flaggers on projects that will only last for a few hours or when automatic devices are not feasible due to the location. Second, they recommend using automated flagger devices for projects that will occupy a location for more than a few hours at a time, up to a period of one day.

Automated flagger devices still require one employee to operate them, so it is important to remember that, although this might be safer, it still involves staffing issues. Third, the results recommended using large portable signals on high-volume roads. These signals can be utilized during longer-duration construction projects, on roads with flat shoulders, and at night. Using full-sized automatic traffic signals does come with specific challenges – they require more time and expertise to set up, and their cost can be prohibitive. All of these recommendations are based on the goals of increasing safety and reducing staffing problems.

Read the Texas DOT Final Report!

Read the Texas DOT Final Report!

Read the Final Report!

Read the Ohio DOT Final Report!











For More Information Contact:

Melisa Finley

Melisa Finley

Melisa Finley P.E.

Research Engineer
Traffic Operations and Roadway Safety Division,
Work Zone and Dynamic Signs
Texas A&M Transportation Institute
Headquarters and Research Building, Rm 253 College Station, TX 77843-3135

Phone: (979) 845-7596 Ext. 57596






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New Visions From Above & Beyond: Multiple Uses for UAVs in Transportation


Tech Brief

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Many have recently begun to investigate the use and applications of unmanned aerial vehicles (UAVs) in the transportation industry.  Researchers at Michigan Tech University have looked at several aspects of these applications as part of a research project with the Michigan Department of Transportation.  In their research they used UAVs to analyze roads, take 3D images of bridge decks, record traffic crash scenes, fly under bridges, and investigate various public utility structures.


Five main types of UAVs were evaluated in this project- a 6 rotor UAV, a small 4- rotor UAV, a mini UAV, a micro UAV, and a small blimp.

Each platform was equipped with a variety of cameras, thermal sensors, and LiDAR.  Several different types of transportation structures, including bridges, roads, pump stations, road construction sites, and roadway assets (including signs) were analyzed. In addition, a simulated crash scene reconstruction scenario was investigated as part of the study.

The 6 rotor UAV, a U.S.-made Bergen Hexacopter, was equipped with a Nikon D800 camera, a Hokuyo UTM-30LX EW LiDAR, and a Tau 2 FLIR thermal camera for various data collections. It was used to collect data and to carry out thermal sensing and 3D imaging (photogrammetry) of bridge decks. This let the team assess various bridge conditions including finding weak spots in the concrete and fatigue and flaws in the steel. This UAV also used cameras to collect data so that it could automatically recognize both signs and traffic lights.

The small 4- rotor UAV, a DJI Phantom Vision 2, had an integrated camera and was easy to fly, and was great for quick pictures and videos of traffic flow. It was to collect images at construction sites and simulated crash sites, and for visual inspection of bridges and the investigation of different structures conditions.

The “mini UAV”, a 4- rotor the Blackout Mini H Quadcopter (11 x 13 in), was also equipped with an integrated camera, and was designed to work in confined spaces such as pumping stations, tunnels, and culverts. It can be equipped with different cameras and sensors, depending on the project.

The 4- rotor micro UAV, a Helimax or Walkera Q 100S, was only 5 x 5 inches, and could fit in the palm of your hand. This UAV can fly inside almost any structure as well as over and around bridges. It uses a very small camera with a memory card so that it can either record images, or transmit live video back to a controller, such a person at an entrance to a confined space evaluating the safety of entry.

A small blimp was the final UAV application to be analyzed. The blimp had a Samsung 4G Camera and monitored traffic for several days. This platform produced near live video which was transmitted via cell phone signal, including to a demonstration traffic operations center during the Intelligent Transportation System (ITS) World Congress in Detroit, MI.

Another piece of equipment, the FPV Factory Mariner Waterproof Quadcopter UAV, was evaluated through this study. It was used to fly over or float on water and it worked well for analyzing underside bridge conditions that would otherwise require a diver or boat deployment to see and evaluate.

Conclusions and Recommendations

Read the Final Report!

Read the Final Report!

This research clearly shows that the applications for UAVs in transportation is limited only by the imagination. The combination of sensors and platforms that were developed for this research have moved in the past 15 years from science fiction to reality.

In a budget limited environment, these flexible remote sensing technologies can help address transportation agency needs in operations, maintenance, and asset management while increasing safety and decreasing cost.

Contact for More Information:

Colin Brooks

Colin Brooks

Mr. Colin

Senior Research Scientist
Manager of Environmental Science Laboratory
Michigan Tech Research Institute (MTRI)
3600 Green Court, Suite 100
Ann Arbor, MI 48105
Office Phone: 734-913-6858

Project Website:


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In the comments below, share with us:

What do you think are the most innovative applications of UAVs in transportation today?  Which of the applications in Colin’s research did you find most interesting?