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Publication Number: FHWA-HRT-04-139
Date: December 2005

Enhanced Night Visibility Series, Volume VIII: Phase II—Study 6: Detection of Pavement Markings During Nighttime Driving in Clear Weather

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Figure 1. Equation. Contrast Ratio. C equals a quotient with a numerator of the difference between L sub T and L sub B and a denominator of L sub B. Back to Figure 1.

Figure 2. Photo. Application of the liquid system pavement marking. The photo shows a mobile truck-mounted, self-contained pavement marking machine applying a white edge line on the Smart Road at the testing facility. The weather conditions are clear and sunny, and there is no frost or moisture on the roadway. Back to Figure 2.

Figure 3. Photo. Application of the fluorescent thermoplastic pavement marking system. This photo shows the handcart used to apply the thermoplastic. The weather conditions are clear and sunny, and there is no frost or moisture on the roadway. Back to Figure 3.

Figure 4. Photo. Application of fluorescent pavement markings using the long-line truck. The photo shows a conventional long-line truck used by the State department of transportation applying fluorescent paint on the Smart Road at the testing facility. The weather conditions are clear and sunny, and there is no frost or moisture on the roadway. Back to Figure 4.

Figure 5. Photo. SUV 1 with hybrid UV–A + HID. The photo shows two hybrid UV–A headlamps and two high intensity discharge headlamps attached to a modular light rack bar that is attached to the front of an experimental sport utility vehicle. The high intensity discharge headlamps are mounted on the far right and far left front, and the hybrid UV–A headlamps are mounted adjacent to them toward the center of the vehicle. Back to Figure 5.

Figure 6. Photo. SUV 2 with three or five UV–A and HLB or HID. The picture shows the front end of a sport utility vehicle with the headlamps removed and a modular light rack attached. In front of the vehicle's own headlamps are two HLB headlamps. Taking up almost all the space between them are three round, black UV–A headlamps. Two more UV–A headlamps hang beneath the HLB headlamps. Back to Figure 6.

Figure 7. Photo. Pickup with HOH and HHB. The photo shows two high output halogen headlamps and two halogen high-beam headlamps attached to a modular light rack on the front of an experimental pickup truck. One high output halogen headlamp and one halogen high-beam headlamp are housed together on the right front of the vehicle, and the other pair is housed together on the left front of the vehicle.
Back to Figure 7.

Figure 8. Photo. Sedan with HLB–LP. The photo shows the front of the experimental sedan used in the study. The sedan is equipped with standard halogen low-beam headlamps. Back to Figure 8.

Figure 9. Photo. Smart Road. The photo, taken on a clear, sunny day, is an aerial view of a section of the Smart Road. The section of road is fairly straight with one gradual curve. The photo shows that there are no other structures in the immediate vicinity. Back to Figure 9.

Figure 10. Diagram. Pavement marking material setup. The diagram depicts the Smart Road facility roadway surface where the three pavement marking materials were applied. The diagram from an overhead perspective shows a slightly curved road with a turnaround at each end. It is noted that the section of road is approximately 1.7 miles long and that the only direction of travel during data acquisition was up the road. The diagram shows that the fluorescent, acrylic-based paint with drop-on glass beads was applied at the bottom of the road and notes that 1,333.8 feet of the pavement markings were exposed. The fluorescent thermoplastic with drop-on glass beads was applied toward the middle section of road, and 606.4 feet of the pavement markings were exposed. The liquid system was located at the top section of road, and 1,010 feet were exposed. Back to Figure 10.

Figure 11. Bar graph. Student-Neuman-Keuls post hoc results on beginning detection distance for the main effect: VES. The graph is titled "Beginning Detection Distance by VES." The X-axis is labeled "Vision Enhancement System," and the Y-axis is labeled "Mean Distance (unit: feet)." A bar is present for each of the 11 vision enhancement systems. Letters above each bar indicate the Student-Neuman-Keuls groupings. The graph shows that with the exception of HLB–LP, the values for all HLB conditions (ranging from approximately 290 to 310 feet) are significantly greater than those of all the HID conditions (ranging from approximately 255 feet to 265 feet), the HHB (approximately 260 feet), and the HLB–LP (approximately 240 feet). Beginning detection distance for HOH (approximately 280 feet) was significantly smaller than that for hybrid UV–A + HLB (approximately 310 feet) and significantly greater than that for HHB (approximately 260 feet), all HID conditions, and HLB–LP. HLB–LP had the lowest beginning detection distance at approximately 240 feet. Back to Figure 11.

Figure 12. Bar graph. Student-Neuman-Keuls post hoc results on beginning detection distance for the main effect: pavement marking. The graph is titled "Beginning Detection Distance by Pavement Marking." The X-axis is labeled "Pavement Marking," and the Y-axis is labeled "Mean Distance (unit: feet)." There is a bar for each of the three pavement marking types. Letters above each bar indicate the Student-Neuman-Keuls groupings. The graph shows that the mean beginning detection distance for fluorescent thermoplastic (approximately 285 feet) and the liquid system (approximately 285 feet) were both significantly greater than that for the fluorescent paint (approximately 245 feet). Back to Figure 12.

Figure 13. Bar graph. Results on beginning detection distance for the interaction: VES by Pavement Marking. The graph is titled "Beginning Detection Distance for the VES by Pavement Marking Interaction." The X-axis is labeled "Vision Enhancement System," and the Y-axis is labeled "Mean Distance (unit: feet)." Three bars represent the three different pavement markings for each VES. Values were comparable for the HLB conditions (HLB–LP excepted) and HOH for each of the pavement marking types. Fluorescent paint detection distances for these VESs ranged from approximately 265 to 300 feet. Fluorescent thermoplastic detection distances for these VES ranged from approximately 285 to 320 feet, and the liquid system detection distances ranged from approximately 305 to 315 feet. Differences emerge when examining the HHB, all HID conditions, and HLB–LP, where detection distances for fluorescent paint (approximately 200 to 230 feet) were modestly lower in comparison to fluorescent thermoplastic (approximately 250 to 300 feet) and the liquid system (approximately 255 to 310 feet). Back to Figure 13.

Figure 14. Bar graph. Student-Neuman-Keuls post hoc results for beginning detection distance for the main effect: age. The graph is titled "Beginning Detection Distance by Age Group." The X-axis is labeled "Age," and the Y-axis is labeled "Mean Distance (unit: feet)." There is a bar for each age group. The graph shows that the mean distance for young participants (approximately 300 feet) was significantly greater when compared to middle-aged (approximately 265 feet) and older participants (approximately 255 feet). Back to Figure 14.

Figure 15. Bar graph. Student-Neuman-Keuls post hoc results on ending detection distance for the main effect: VES. The graph is titled "Ending Detection Distance by VES." The X-axis is labeled "Vision Enhancement System," and the Y-axis is labeled "Mean Distance (unit: feet)." The graph shows that mean distances for HLB conditions (ranging from approximately 240 to 250 feet), with the exception of HLB–LP, are significantly greater than values for the HID conditions (ranging from approximately 195 to 215 feet), and the HLB–LP (approximately 180 feet). HHB (approximately 220 feet) is significantly smaller than
five UV–A + HLB, HLB, and HOH (ranging approximately from 245 to 255 feet) and significantly greater than hybrid UV–A + HID (approximately 195 feet) and HLB–LP (approximately 180 feet). Back to Figure 15.

Figure 16. Bar graph. Student-Neuman-Keuls post hoc results on ending detection distance for the main effect: pavement marking. The graph is titled "Ending Detection Distance by Pavement Marking." The X-axis is labeled "Pavement Marking," and the Y-axis is labeled "Mean Distance (unit: feet)." There is a bar for each type of pavement marking. The graph shows that the mean detection distance for the liquid system (approximately 235 feet) was significantly greater than the distance for the fluorescent paint (approximately 205 feet); however, neither was different than fluorescent thermoplastic (approximately 230 feet).
Back to Figure 16.

Figure 17. Bar graph. Results on ending detection distance for the VES by Pavement Marking interaction. The graph is titled "Ending Detection Distance for the VES by Pavement Marking Interaction." The X-axis is labeled "Vision Enhancement System," and the Y-axis is labeled "Mean Distance (unit: feet)." Each VES system has three bars, representing the three pavement marking types. The graph demonstrates that values generally were comparable for the different pavement marking types within each VES condition. HHB was an exception where detection distance of the liquid system (approximately 270 feet) was longer than the detection distance of the fluorescent paint (approximately 175 feet) and the fluorescent thermoplastic (approximately 225 feet). Detection distance for the fluorescent paint across the VESs ranged from approximately 175 feet with HHB to 240 feet with five UV–A + HLB. The detection distance for the fluorescent thermoplastic across the VESs ranged from approximately 195 feet with HLB–LP to 255 feet with HOH. The detection distance for the liquid system across the VESs ranged from approximately 190 feet with hybrid UV–A + HID to approximately 270 feet with the HHB and five UV–A + HLB. Back to Figure 17.

Figure 18. Bar graph. Student-Neuman-Keuls post hoc results on ending detection distance for the main effect of age. The graph is titled "Ending Detection Distance by Age." The X-axis is labeled "Age," and the Y-axis is labeled "Mean Distance (unit: feet)." The graph shows that the distance for young participants (approximately 290 feet) was significantly greater when compared to middle-aged (approximately 220 feet) and older (approximately 230 feet) participants. Back to Figure 18.

Figure 19. Photo. Aerial view of the Smart Road. The photograph shows a paved road with a large turnaround at one end extending down into a valley at the other end. Back to Figure 19.

Appendix C: Contrast Sensitivity Test Diagram. The diagram shows the form the experimenters used to document the results for each participant's contrast sensitivity exam. The diagram shows a graph with contrast sensitivity from 3 to 300 on the left Y-axis, contrast threshold from .3 to .003 on the right Y-axis, and spatial frequency (cycles per degree) from .5 to 6 on the X-axis. There is a column of numbered circles above each cycle per degree, indicating participant response. There are two diagrams, one for recording the results of the right eye and one for the results of the left eye. Back to Diagram.

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