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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 one of the research tools used at 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. Five projectors render a seamless 240-degree view (motorists' field-of-view) of high-fidelity, computer-generated roadway scenes.

The photo shows a male driver inside a full automobile chassis surrounded by a semicircular projection screen. The automobile and the project screen are located inside a darkened room. The screen displays a roadway scenario featuring other automobiles, traffic lights, roadway markings, and traffic signs.

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 to enhance the motion base, from 3 to 6 degrees of freedom. This improvement makes the motion and vestibular (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) so the researchers can investigate where participants are looking when they drive through the 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 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 over 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 novel design, one human factors concern was that drivers might become confused and make a dangerous maneuver. To evaluate this concern, the FHWA researchers created visualizations in the simulator of various driving scenarios.

Click here for videos.

 

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 image from FHWA's driving simulator shows a sample scenario used in a human factors study of the double crossover diamond interchange

 

The Missouri Department of Transportation (MoDOT) designed and built the first U.S. 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. At the same time, the laboratory’s researchers provided feedback on the details of the MoDOT design. This 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.

The photo shows a sport utility vehicle parked on a roadway. The vehicle has three cameras mounted on the outside roof, toward the front of the vehicle that reach from the left side of the windshield to the right side. These cameras record the forward driving scene.

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

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 would also like 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)

A field research vehicle, 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.

The photo shows a male driver inside the sport utility vehicle. Three cameras, which are circled in the image, are mounted on the dashboard and aimed at the driver. The cameras are not attached to the driver. The cameras help track the head position and gaze of the driver.

An eye-tracking device (the three circled cameras) in this 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 panorama of the driving scene in front of the vehicle, together providing an 80-degree-wide by 40-degree-high field of the forward view. 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 to examine where drivers look when they are driving past commercial electronic variable message signs and standard billboards. The laboratory measured the signs and billboards with respect to luminance, location, size, and other relevant variables.

 

Sign Design and Research Facility

Another facility at the Human Factors Laboratory is known as the “sign lab,” but is formally called the Sign Design and Research Facility. 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. 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 TV as a researcher displays a sign as a small distant object and then enlarges it 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 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?"

 

The photo shows a room with a small desk and a chair located in front of a table on which sits a high-definition television connected to a computer control center. The screen displays six traffic signs: three signs on the top row and three on the bottom row. Two signs on the top row – the sign on the far left and the sign on the far right – have two downward-facing arrows. The arrows point to the lower-left corner of the box. The middle box contains text, which is not legible in the photo. Two signs on the bottom row – the sign on the far left and the sign on the far right, have text which is not legible in the photo. The middle box contains an arrow that is pointing to the lower-left corner of the box.

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-, six-, 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 www.pooledfund.org/Details/Study/281for 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. In addition, 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 clearly outperformed the three other alternatives, garnering correct responses 95 percent of the time. In the case of the four alternatives for the TRUCK ROLLOVER sign, however, the results revealed no statistically significant differences in performance.

 

The photo shows a table with six columns and eight rows, making 48 boxes. The table is used to examine sign legibility and drivers’ comprehension. The columns are labeled Sign Category, Alt 1, Alt 2, Alt 3, Alt 4, and Alt 5. The rows are labeled Sign Category, Alternate Merge, Bike Symbol, Grade Crossing (“Crossbuck” in parentheses), Pedestrian Crossing, Truck Rollover with Advisory Speed Limit, Trucks in Roundabouts, Weave Symbol (“Diverge” in parentheses). 
In the first row marked Alternate Merge, the sign under Alt 1 is yellow and diamond shaped and has a black border. The sign shows a thick, vertical line on the left, which angles toward the right half way up. Another line shows a thick, vertical line on the right, which angles toward the left half way up. There is also a thin, short vertical dotted line between the angled lines that is the length of the vertical section of the angled lines. The sign under Alt 2 is yellow and diamond shaped and has a black border. The sign includes a dashed line in the center surrounded by two thick, black lines that angle inward and connect. The lines form a thick black arrow that points up. There is a thin, black line on each side of the thick, black lines. The sign under Alt 3 is yellow and diamond shaped and has a black border. The sign includes the word Alternate, which is located above the word Merge. The words are in all capital letters. The sign under Alt 4 is yellow and diamond shaped and has a black border. The word Form is above the word One, which is above the word Lane. All words are in capital letters. The sign under Alt 5 is yellow and diamond shaped and has a black border. The sign includes the word Single above the word Lane, which is above the word Ahead. All words are in capital letters.
In the second row marked Bike Symbol, the sign under Alt 1 is yellow and diamond shaped and features a representation of a left-facing bicycle. The sign under Alt 2 is yellow and diamond shaped and features a representation of a person on a left-facing bicycle. The person is seen holding the handlebars. The sign under Alt 3 is yellow and diamond shaped and features a representation of a person on a left-facing bicycle. The image does not include handlebars. The difference between the sign under Alt 2 and Alt 3 is the bicycle rider in the Alt 3 sign is more hunched over, as if in a race, and the bicycle rider in Alt 2 is sitting up straighter, as if riding slower. In both the Alt 4 and Alt 5 columns, the word None is centered in each box.
In the third row marked Grade Crossing (Crossbuck in parentheses), the sign under Alt 1 is a white X that is outlined in black. The inside of the X is white, and the word Rail is printed on the top-left portion of the X. The word Road is printed on the lower-right portion of the X. Beginning in the lower-left portion of the X and continuing to the top-right portion, the word Crossing is printed. The sign under Alt2 is a white X that is outlined in red. There are no words in the X. The sign under Alt 3 is a white X that is outlined in red. The inside of the X is white, and the word Rail is printed on the top-left portion of the X. The word Road is printed on the lower-right portion of the X. Beginning in the lower-left portion of the X and continuing to the top-right portion, the word Crossing is printed. In both the Alt 4 and Alt 5 columns, the word None in centered in each box.
In the fourth row marked Pedestrian Crossing, the sign under Alt 1 is yellow and diamond shaped and features a representation of a left-facing walking person. There is a small, yellow, rectangular box under that sign with a black arrow pointing to the lower-left corner of the box, indicating where the crosswalk would be located. The sign under Alt 2 is white and rectangular and outlined in black. A Yield sign (an inverted red triangle with Yield centered in the triangle and printed on top of a white background) is located at the top of the square. Under and to the left of the Yield sign, the word Here is printed in all capital letters. Under and to the right of the word Here, a black arrow is curved and pointing to the lower-left corner of the square. Under the arrow, the word To is printed, and behind the word To, there is an image of a person walking. The sign under Alt 3 is white and rectangular and outlined in black. A Stop sign (a red octagon with Stop centered in the octagon and printed in white in all capital letters) is located at the top of the square. Under and to the left of the Stop sign, the word Here is printed in all capital letters. Under and to the right of the word Here, a black arrow is curved and pointing to the lower-left corner of the square. Under the arrow, the word To is printed, and behind the word To, there is an image of a left-facing person walking. The sign under Alt 4 is a long, yellow rectangle. The words State Law are printed on top of the rectangle in black and in all capital letters. The words Within Crosswalk are printed in black and in all capital letters at the bottom of the sign. Below the word Law is an area in white. In the top of the white area, there is a Yield sign. Beneath the Yield sign the word To is printed in black and in all capital letters. Under the word To, there is a representation of a left-facing walking person. The sign under Alt 5 is a long, yellow rectangle. The words State Law are printed on top of the rectangle in black and in all capital letters. The words Within Crosswalk are printed in black and in all capital letters at the bottom of the sign. Below the word Law is an area in white. In the top of the white area, there is a Yield sign. Beneath the Yield sign the word To is printed in black and in all capital letters. Under the word To, there is a representation of a left-facing person walking.  
In the fifth row marked Truck Rollover with Advisory Speed Limit, the sign under Alt 1 is yellow and diamond shaped with a black border. It shows a straight black line toward the bottom of the sign with an image of a tractor trailer tilting toward the left at a 45-degree angle. Above the tractor trailer is a curved arrow pointing down to the right. The arrow is centered in the diamond-shaped sign. Beneath the diamond-shaped sign, a small, square, yellow sign appears with 35 printed in large black numbers. Beneath 35, MPH appears in smaller, upper-case letters. The sign under Alt 2 is yellow and diamond shaped with a black border. It shows a straight black line toward the bottom of the sign. Above the straight line is a curved arrow pointing down to the right. The arrow is centered in the diamond-shaped sign. Beneath the diamond-shaped sign, a small, square, yellow sign appears with 35 printed in large black numbers. Beneath 35, MPH appears in smaller, upper-case letters. The sign under Alt 3 is yellow and diamond shaped with a black border. It shows a straight black line toward the bottom of the sign with an image of a tractor trailer tilting toward the left at a 45-degree angle. Above the tractor trailer is a curved arrow pointing to the right. The arrow is not centered in the sign; it is above the tractor trailer and toward the left side of the sign. Beneath the diamond-shaped sign, a small, square, yellow sign appears with 35 printed in large black numbers. Beneath 35, MPH appears in smaller, upper-case letters. The sign under Alt 4 is yellow and diamond shaped with a black border. It shows a straight black line toward the bottom of the sign. Above the straight line is a curved arrow pointing to the right. The arrow is not centered in the sign; it is above and toward the left side of the sign. Beneath the diamond-shaped sign, a small, square, yellow sign appears with 35 printed in large black numbers. Beneath 35, MPH appears in smaller, upper-case letters. In the Alt 5 column, the word None in centered in the box.
In the sixth row marked Trucks in Roundabouts, the sign under Alt 1 is yellow and diamond shaped and has a black border. Inside the sign, Watch for Wide Turning Trucks is printed in all capital letters and centered within the sign. The sign under Alt 2 is yellow and diamond shaped and has a black border. There is an image of a tractor trailer and arrow indicating that the tractor trailer is about to make a left turn. A car is seen on the tractor trailer’s left side. The sign under Alt 3 is a long, white, rectangular sign with a black border. It shows a tractor trailer driving in the center of a two-lane road, with two cars behind the tractor trailer, one in the left lane and one in the right lane. Under the image, Trucks Use Both Lanes is printed in all capital letters. In the Alt 5 column, the word None in centered in the box.
In the seventh row marked Weave Symbol (Diverge in parentheses), the sign under Alt 1 is yellow and diamond shaped and has a black border. There are two black arrows. One arrow points upward and slants diagonally up and to the left and then straightens to a vertical direction. The other arrow points upward and slants diagonally up and to the right and then straightens to a vertical direction. The arrows intersect in the center of the sign. The sign under Alt 2 is yellow and diamond shaped and has a black border. It shows a solid black line to the left of the center of the sign. A curved line that faces toward the right connects to the solid black line. A dashed line is shown where the two lines connect. The sign under Alt 3 is yellow and diamond shaped and has a black border. There is a thin black line in the center of the sign; the line is solid at the top and dashed at the bottom. There is another line that diverges from the right from the solid line. There are also two black arrows of the same thickness. One arrow points upward and slants diagonally up and to the left and then straightens to a vertical direction. The other arrow points upward and slants diagonally up and to the right to a vertical direction. The arrows intersect below the center of the sign. The sign under Alt 4 is yellow and diamond shaped and has a black border. There is a thin black line in the center of the sign; the line is solid at the top and dashed at the bottom. There is another line that diverges from the right from the solid line. There are also two black arrows. One arrow points upward and slants diagonally up and to the left and then straightens to a vertical direction. The other arrow points upward and slants diagonally up and to the right to a vertical direction. The arrows intersect below the center of the sign. The arrow that points to the left is slightly thinner than the arrow that points to the right. In the Alt 5 column, the word None in centered in the box.

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 also house 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 including 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.

 

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™ 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 one not in a hurry, and 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 drivers' familiarity with a roadway, eliciting states 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