Selection and Application of Warning Lights on Roadway Operations Equipment (2008) / Chapter Skim
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Pages 22-31
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From page 22... ...
Three measures considered the nighttime identifiability of a maintenance vehicle with warning lights; the detectability of a pedestrian standing close to the maintenance vehicle; and the ranking of the vehicle lighting in terms of discomfort glare, attention-getting, and urgency. The study included an uninformed trial where participants viewed the lighting systems without knowing the nature of the study and also incorporated adverse weather in the testing conditions.
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Pedestrian Detection Distance. To establish each warning light's ability to allow a driver to see maintenance workers near a maintenance vehicle, the distance at which a participant could detect a pedestrian standing near the experimental dump truck was recorded.
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24 Figure 4. VDOT dump truck outfitted with warning lights.
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During the nighttime dry trials, the participant drove on the Smart Road toward the experimental dump truck that was displaying one of the four warning lights. The participant would verbally indicate when he or she could identify the light source as a vehicle, and when he or she could detect a pedestrian in the roadway near the truck.
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This result may be related to the light's effective intensity that caused participants to change lanes to avoid glare from the lights. – Results from all other warning lights were not significantly different from each other.
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. – A pairwise SNK analysis also found that the LEDs had a significantly shorter pedestrian detection distance than all other warning lights (Figure 9)
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the lit roadway provided lighting on or near the roadway that made the warning lights seem less glaring by comparison. – On average, the LEDs had the highest discomfort glare ratings, and the high-mounted beacons had the lowest (Figure 14)
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– Distance was a significant factor in all weather conditions, with discomfort glare ratings decreasing with increased distance. • Urgency – For the surprise trial, the high-mounted beacons were rated significantly lower for urgency than the other warning lights.
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Form Factor Method Figure 17. Pedestrian detection distance by the light source effective intensity (Form Factor method)
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• Adverse Weather – The influence of the rain and fog conditions did not seem to significantly influence the participants' subjective ratings of lighting system performance. – The rain and fog significantly reduced the vehicle identification and pedestrian detection distances for all the light sources and seemed to moderate the differences between the systems except for the LEDs.
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