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Effects of Warning Lamps on Pedestrian Visibility and Driver Behavior

NCJ Number
Date Published
April 2007
38 pages
This field study was conducted in order to provide information on how warning lamps for parked emergency vehicles affect the vision and driving performance of passing civilian drivers, with a focus on ways in which the warning lamps might adversely impact safety.
Attention is given to those situations in which an emergency responder is standing or working near a parked emergency vehicle with warning lights flashing. The concern is that in such situations, the warning lamps may create glare for oncoming drivers, possibly reducing their ability to see and avoid emergency workers near the emergency vehicle. The study found that under the test conditions used, warning lamps did not have significant effect on participants' driving behavior in allowing sufficient lateral clearance when passing the experimental scene. When simulated emergency workers (mannequins) wore clothing with retroreflectivity, drivers allowed greater lateral clearance when passing the scene. The report recommends that future extensions of this study examine how the effects of color observed in the nighttime conditions of the current study might be altered under daytime conditions and how well subjective ratings of conspicuity correspond to objective measures of the effectiveness of warning lamps in alerting passing drivers to parked emergency vehicles. The study was conducted on a closed-course test track. Participants selected from the driving civilian population were asked to drive on the track at night while attempting to detect pedestrian mannequins that were positioned near a parked vehicle displaying experimental warning lamps. The warning lamps used LED sources and were varied in color (blue, red), flash pattern (steady, flashing in phase, flashing out of phase), and intensity (low, high). The pedestrian mannequins were varied in the level of retroreflective treatment with which they were marked (none, low, and high). 21 figures, 1 table, and 8 tables

Date Published: April 1, 2007