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Human Factors Laboratory

 

Research Tools

 

Highway Driving Simulator Field Research Vehicle Sign Design and Research Facility MiniSim™ Driving Simulator

 

Highway Driving Simulator (HDS)

The Highway Driving Simulator (HDS) is a research tool used in the Human Factors Laboratory for a variety of behavioral studies related to safety and operations conducted for Federal Highway Administration (FHWA) and other stakeholders. The simulator consists of a full automobile chassis surrounded by a semicircular projection screen. Three high-definition projectors render a seamless 200-degree view (motorists' field of view) of high-fidelity, computer-generated roadway scenes. A virtual 360-degree field of view is generated by three liquid-crystal display (LCD) panels used in place of the vehicle's three rearview mirrors.

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Located at FHWA’s research center in McLean, VA, the driving simulator is a high-fidelity, state-of-the-art research tool that the Human Factors Laboratory uses to generate multiple driving scenarios for evaluation and analysis.

 

In 2012, the simulator was upgraded from three degrees of freedom to six degrees of freedom to enhance the motion base. This improvement makes the motion and vestibular perception (the perception of body position and movement) much more realistic for drivers. In addition, the driving simulator has a 120-hertz (Hz) eye-tracking capability (that is, it takes 120 samples per second), which allows researchers to investigate where participants are looking when they drive through various roadway scenarios.

When FHWA introduced the double crossover diamond interchange design in the United States in 2004 in Springfield, MO, the driving simulator played an important role in testing human factors issues related to that interchange. Although France has used the double crossover diamond interchange successfully for 30 years, this freeway interchange design was new to the United States. To assist with U.S. development, Michel Labrousse, director of the Centre d'Etudes Techniques de l'Equipment Normandie-Centre, provided records, signal layouts, and traffic flow and crash data from a groundbreaking installation in Versailles, France.

Many conventional interchanges in urban areas are congested and experience high crash rates. In comparison to a conventional diamond interchange, a double crossover diamond design involves drivers crossing from the right side of the road to the left side and then back, thus combining left-turning and through traffic movements. Because of this new design, one human factors concern was that drivers might become confused and make a dangerous maneuver. To evaluate this concern, FHWA researchers created visualizations in the simulator of various driving scenarios.

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The photo shows a simulated double crossover diamond interchange scenario taken from the driving simulator. The image shows a double crossover diamond interchange containing virtual traffic lights on overhead posts and on posts next to the roadway, various traffic signs (a Do Not Enter sign, a Wrong Way sign, a Left Turn prohibited sign, and onramp signs), and roadway markings (dashed lines, arrow signs).
This screenshot image from FHWA's driving simulator shows a sample
scenario used in a human factors study of the diverging diamond interchange.

 

The Missouri Department of Transportation (MoDOT) designed and built the Nation’s first double crossover diamond interchange in Springfield, MO, and opened it to traffic in June 2009. During the design phase, the Missouri engineers visited the Human Factors Laboratory to virtually drive through a simulated double crossover diamond interchange. At the same time, the laboratory’s researchers provided feedback on the details of the MoDOT design. The visualization and testing in the driving simulator helped to alleviate safety concerns about the new design. The FHWA researchers then created video clips from the simulation scenarios to facilitate outreach to the Missouri public.

A current study using the simulator examines issues related to driver distraction. Researchers are investigating whether advertising on changeable message signs is distracting to drivers. Some of the measures used in the study include the number and duration of eye glances to each sign, and whether participants notice a sign telling them to exit the freeway because there is a crash ahead. The researchers also want to determine whether there is any correlation between potential distraction from advertising on changeable message signs and safety concerns. The study is in the data-collection phase, and the results are expected to take another year.

 

Field Research Vehicle (FRV)

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Researchers at FHWA's Human Factors Laboratory use this field research vehicle to conduct onroad experiments to understand driver behavior and performance better.

A field research vehicle (FRV), an instrumented 2007 sport utility vehicle (SUV), is another tool in use at the Human Factors Laboratory. The SUV is outfitted with equipment to record GPS position, vehicle speed, and vehicle acceleration. The vehicle also is equipped with a state-of-the-art eye-tracking system that consists of two infrared light sources and three cameras mounted on the dashboard facing the driver. These cameras and lights are small and are not attached to the driver in any manner. The cameras are synchronized to the light sources and help track the head position and gaze of the driver.

An eye-tracking device in the field research vehicle helps researchers study where drivers are looking when they drive through various roadway environments. There are three additional cameras mounted on the exterior of the vehicle's roof, directly above the driver's position, for capturing the forward driving scene. The cameras capture the panoramic view of the driving scene in front of the vehicle, and provide a forward view that is 80 degrees wide and 40 degrees high. The forward view area reaches from the left side of the windshield to a portion of the right side.

The research vehicle was used to collect data for a study that examines where drivers look when they are driving past commercial electronic variable message signs and standard billboards. The laboratory measured the signs and billboards for luminance, location, size, and other relevant variables.

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Sign Design and Research Facility

The Sign Design and Research Facility is another facility at the Human Factors Laboratory. It’s commonly referred to as the "sign lab." This facility consists of a 60-inch (152-centimeter) light-emitting diode/liquid crystal display (LED/LCD) high-definition television connected to a computer control center. A new infrastructure design software suite was recently added to the laboratory that will enable the rapid development of interactive static or dynamic roadway simulation environments. This new software will allow for better sign development, replication of existing signs, and the development of realistic roadways (including the use of existing geographic information system (GIS) data).

The sign lab enables researchers to present traffic signs to participants in a controlled environment. When developing new traffic signs, researchers need to determine the maximum distance at which participants can recognize and comprehend signs.

To do this, a participant sits at the computer and looks at the screen as a researcher, sitting at the control panel behind the participant, displays a sign of a small, distant object and then enlarges it using specially designed software so that its appearance approximates the way it would be viewed as a vehicle approaches the sign at a specified speed. The researcher then uses the size of the image at the moment the participant says that he or she recognizes it to approximate the sign's recognition sight distance. The computer precisely controls the sign display duration and image size, and measures the participant's reaction time. The researcher generally records sign comprehension using open-ended questions relating to the participant's understanding of the traffic sign. For example, the research might ask, "If you were driving and saw this sign, what action would you take?"

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When developing new traffic signs, researchers need to determine the maximum distance at which motorists can recognize and comprehend a sign. The FHWA sign lab, shown here, enables researchers to present traffic signs to participants in a controlled environment and study their responses.

 

Recently, FHWA researchers at the sign lab conducted two studies funded by the Traffic Control Device Consortium Pooled Fund Program, which combines States' funds into a pool for Federal research. The first study evaluated identification signs at freeway interchange approaches and the efficacy of the signs at providing motorists with information based on business logos. Currently, the Manual on Uniform Traffic Control Devices (MUTCD) limits the number of business logos on a single interchange approach sign to six. Whether increasing or decreasing this number would produce favorable results was one aspect of the study. The research also evaluated the effectiveness of using businesses' logos versus standard highway sign text.

The researchers showed 103 participants multiple combinations of four-panel, six-panel, and nine-panel signs, an example of which is shown below.

An example of the four-, six-, and nine-panel signs.
An example of the four-panel, six-panel, and nine-panel signs.

They displayed the signs on the television screen at a simulated distance of 121 feet (37 meters), approximately half the minimum legibility distance. Results suggested that participants were less able to identify specific business logos accurately compared to standard text on highway signs. (See FHWA Traffic Control Device Pooled Fund Program for more information.)

Participants also needed more time to identify artistic logos. Across each of the panels, identification accuracy was higher starting at the top of the sign and shifting downward from left to right. Additionally, more signs on a panel resulted in more eye glances away from the simulated road. Results from this study showed that any benefit of providing drivers with more service information, such as nine-panel signs, is outweighed by the potential risk of increasing driver distraction. The second study performed in the sign lab examined the legibility of multiple alternatives of symbols listed in the MUTCD. The alternatives were either currently used internationally, were State specific, or were generated by the lab or elsewhere. Each research participant evaluated each symbol. The team exposed the participants to scenarios containing each of the sign alternatives for each of the sign groups.

For legibility testing, the researchers used software designed to increase the size of the sign gradually, simulating how the sign would appear as a motorist drives toward it at a specified speed. The researchers then measured the legibility distance for each sign. Following each scenario, the team recorded the participants' comprehension using open-ended and multiple choice questions, and by the participants' rankings of how well they thought the signs would work.

Results showed that some alternatives clearly performed better than others, while other comparisons were not as definitive. For instance, under the multiple choice questions, Alternative 2 of the WEAVE Symbol (DIVERGE) clearly outperformed the three alternatives, garnering correct responses 95 percent of the time. In the case of the four alternatives for the TRUCK ROLLOVER WITH ADVISORY SPEED LIMIT sign, however, the results revealed no statistically significant differences in performance.

 

Please click on an individual image to get more information

Sign CategoryAlt.1Alt.2Alt.3Alt.4Alt.5
Alternate
Merge
Alt 1 - This is an Alternate Merge sign that shows two lanes merging into a single lane. Alt 2 - This is an Alternate Merge sign that shows two lanes merging into a single lane. Alt 3 - This is an Alternate Merge sign that reads Alternate Merge. Alt 4 - This is an Alternate Merge sign that reads Form One Lane. Alt 5 - This is an Alternate Merge sign that reads Single Lane Ahead.
Bike SymbolAlt 1 - This Bicycle Sign shows a side view of a forward-facing bicycle. Alt 2 - This Bicycle sign shows a side view of a forward-facing bicycle. A person with a helmet is shown riding the bicycle. Alt 3 - This Bicycle sign shows a side view of a forward-facing bicycle. A person with a helmet is shown riding the bicycle. None None
Grade Crossing
(Crossbuck)
Alt 1 - This Grade Crossing symbol is in the shape of an X with the words reads Railroad Crossing displayed in all capital letters.
Alt 2 - This Grade Crossing symbol is in the shape of an X that is outlined in red. Alt 3 - This Grade Crossing symbol is in the shape of an X that is outlined in red with the words reads Railroad Crossing displayed in all capital letters. None None
Pedestrian
Crossing
Alt 1 - This Pedestrian Crossing sign shows a left-facing walking figure with a small sign beneath it that includes a downward left-pointing arrow. Alt 2 - This Pedestrian Crossing sign shows a left-facing walking figure beneath a Yield sign, indicating the driver must yield to pedestrians.
Alt 3 - This Pedestrian Crossing sign shows a left-facing walking figure beneath a Stop sign, indicating that the driver must stop for pedestrians. Alt 4 - This alternative Pedestrian Crossing sign shows a left-facing walking figure beneath a Yield sign, indicating the driver must yield to pedestrians.
 Alt 5 - This alternative Pedestrian Crossing sign shows a left-facing walking figure beneath a Stop sign, indicating that the driver must stop for pedestrians.
Truck Rollover
with Advisory
Speed Limit
Alt 1 - This Truck Rollover with Advisory Speed Limit sign shows an image of a truck tipping over, which is above a 35 MPH sign. Alt 2 - This alternative Truck Rollover with Advisory Speed Limit sign shows a curved arrow pointing down and toward to right, which is above a 35 MPH sign. Alt 3 - This Truck Rollover with Advisory Speed Limit sign shows an image of a truck tipping over beneath a right-pointing curved arrow, which is above a 35 MPH sign.
Alt 4 - This alternative Truck Rollover with Advisory Speed Limit sign shows a curved arrow pointing toward to the right, which is above a 35 MPH sign.
None
Truck in
Roundabouts
Alt 1 - This Trucks in Roundabouts sign displays the text reads, Watch for Wide Turning Trucks, written in all capital letters. Alt 2 - This Trucks in Roundabouts sign displays a truck attempting to turn left with a car in its way. Alt 3 - This Trucks in Roundabouts sign displays a truck on a roadway in the middle of the road with two cars behind it. A sign below the image reads Trucks Use Both Lanes, written in all capital letters. Alt 4 - This Trucks in Roundabouts sign reads, Trucks Use Both Lanes, written in all capital letters.
None
Weave Symbol
(Diverge)
Alt 1 - This Weave Symbol (Diverge) shows two intersecting arrows. Alt 2 - This Weave Symbol (Diverge) shows a straight line and a connected curved line, with dashed road markings in the middle of the lines.
Alt 3 - This Weave Symbol (Diverge) shows two intersecting arrows over a straight line with a connected curved line attached. There is a dashed line beneath the straight line. Alt 4 - This Weave Symbol (Diverge) shows two intersecting arrows over a straight line with a connected curved line attached. There is a dashed line beneath the straight line. None
In a study that examined sign legibility and drivers' comprehension, researchers asked participants to compare signs listed in the MUTCD to multiple alternatives.

 

MiniSim™ Driving Simulator

 

In partnership with the National Highway Traffic Safety Administration (NHTSA), the Human Factors Laboratory houses a MiniSim™ driving simulator, a part-task simulator consisting of a quarter-cab setup that includes an adjustable driver's seat; driver controls, such as pedals and a steering wheel; and a meter cluster that includes a speedometer. The MiniSim™ has three 42-inch (107-centimeter) forward-display LCD televisions, software, and computers for generating driving scenes and controlling vehicle dynamics.

 

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The photo shows the MiniSim, which consists of a quarter-cab setup that includes an adjustable driver's seat, pedals (which are not visible in this image), a steering wheel, and a meter cluster that includes a speedometer. The MiniSim™ has three forward-display LCD televisions. On the far left screen, a simulated side-view mirror is shown. On the far right screen, a simulated rearview mirror is shown. The televisions display a two-lane roadway with yellow lines in the center of the road.  A telephone pole and a road sign on the right side of the road are shown in the center screen. The road sign is not legible in the photo. There are also two trees shown on the left side of the center screen. There is a field of trees in the far right screen and a grassy area with a few trees in the far left screen. The photo shows the MiniSim, which consists of a quarter-cab setup that includes an adjustable driver's seat, pedals (which are not visible in this image), a steering wheel, and a meter cluster that includes a speedometer. The MiniSim™ has three forward-display LCD televisions. On the far left screen, a simulated side-view mirror is shown. On the far right screen, a simulated rearview mirror is shown. The televisions display a two-lane roadway with yellow lines in the center of the road.  A telephone pole and a road sign on the right side of the road are shown in the center screen. The road sign is not legible in the photo. There are also two trees shown on the left side of the center screen. There is a field of trees in the far right screen and a grassy area with a few trees in the far left screen.

The MiniSim™ driving simulator shown here enables researchers to conduct low-cost studies to answer specific questions or preliminary research prior to a larger scale test.

 

The MiniSim™ is useful for evaluating driver performance in simple environments, such as various infrastructure-related studies that do not require the full immersion of high-fidelity driving simulation. This tool enables researchers to conduct low-cost studies to answer specific questions or to conduct preliminary research prior to a large-scale simulation or onroad research.

A recent study using the MiniSim™ examined driver performance on horizontal curves of rural two-lane roadways. According to the Fatality Analysis Reporting System, a total of 23,740 fatalities resulted from run-off-road crashes on the horizontal curve sections of rural two-lane roadways from 2005 to 2009; an average of 4,748 fatalities per year. An analysis of the National Motor Vehicle Crash Causation Survey suggests that a driver who is familiar with a roadway is twice as likely to be involved in a run-off-road crash as one who is unfamiliar with it. In addition, a driver who is in a hurry is 3.2 times more likely to be involved in a run-off-road crash than a driver who is not in a hurry. Also, an inattentive driver is 3.7 times more likely to be in a crash than an attentive driver.

The research team examined possible procedures for establishing a driver’s familiarity with a roadway, eliciting a state of distraction because of being in a hurry, and determining the effect of these factors on driver performance on rural two-lane horizontal curves, as compared to baseline conditions. Measurements included vehicle speed and lane positioning.

Results indicate that the methodological procedures were effective at simulating the precipitating events and might be useful in future experiments by providing realistic driving situations for the development of dynamic traffic control devices using simulation.

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Laboratory Manager

Yang, David
david.yang@dot.gov
202-493-3284

Turner-Fairbank Highway Research Center
6300 Georgetown Pike
McLean, VA 22101-2296

 

Other Links

» FHWA's Office of Safety
» Resource Center Safety and Design Team
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101