LED Roadway Lighting: Impact on Driver Sleep Health and Alertness (2021) / Chapter Skim
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Pages 22-35
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22 To address the project goals, two separate experiments were conducted: the Corneal Illuminance Dosage Experiment and the Driver Sleep Health and Alertness (DSHA) Experiment.
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Methods 23 to Virginia Department of Transportation (VDOT) and FHWA standards.
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24 LED Roadway Lighting: Impact on Driver Sleep Health and Alertness right track, and are approximately 32 in.
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Methods 25 blue content in the display's spectral power distribution) on the device being activated for the same white-colored screen as the first condition.
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26 LED Roadway Lighting: Impact on Driver Sleep Health and Alertness Driver Sleep Health and Alertness Experiment In this experiment, the effect of an LED roadway lighting type at three corneal illuminances on subjective and objective measures of driver sleep health and alertness were assessed, to determine the corneal illuminance that produces a measurable effect. The same objective and subjective measures of driver sleep health and alertness were also measured for a positive control, a negative control (no roadway lighting)
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Methods 27 is the traditional HID roadway lighting source. These two light sources have different SPDs (see Figure 6)
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28 LED Roadway Lighting: Impact on Driver Sleep Health and Alertness Experimental Approach Participants were recruited from the public to be tested at VTTI under the selected experimental conditions. In the positive laboratory control, a high-intensity LED luminaire at close range was used to suppress the dim-light melatonin onset and peak melatonin secretion.
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Methods 29 and the data were reviewed at the beginning of each experimental session. This ensured that each participant had maintained a normal sleep cycle throughout the experimental period.
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30 LED Roadway Lighting: Impact on Driver Sleep Health and Alertness PERCLOS -- the percentage of time a driver's eyelids are closed over a given period, generally 1 to 3 minutes (Dinges & Grace, 1998; Wierwille et al., 1994) -- has been determined to be a reliable objective measure of driver drowsiness (Dinges et al., 1998)
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Methods 31 Procedure Positive Control Positive control laboratory studies of nocturnal melatonin secretion served as reference points to compare melatonin levels in the experimental driving scenarios on the Smart Road. The objective of the positive control was to strongly suppress the earlier melatonin onset and peak melatonin secretion.
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32 LED Roadway Lighting: Impact on Driver Sleep Health and Alertness Naturalistic Driving Experiment Once the positive laboratory control sessions were completed, the exposure sessions to determine the effects of roadway lighting on DSHA in a naturalistic environment began. Only one lighting condition was experienced during each experimental session, and at least 1 week passed between experimental sessions.
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Methods 33 Participants drove the experimental vehicle from 1:00 AM to 3:00 AM at a speed of 35 mph while using low-beam headlamps. Vehicle speed was actively monitored by the in-vehicle experimenter, who was always seated in the back seat of the experimental vehicle.
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34 LED Roadway Lighting: Impact on Driver Sleep Health and Alertness as these activities might have confounding effects on melatonin level and alertness. Overall, participants completed five such driving sessions separated by a minimum of 1 week between sessions.
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Methods 35 Analyses Linear mixed-model (LMM) analysis was used to assess the effects of lighting type, level, and duration on melatonin level, reaction time, PERCLOS, SDLP, and KSS.
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