A field experiment was performed in which eight different configuration and color combinations of commonly used rotating focused-beam emergency vehicle lights were quantitatively compared over several dimensions of information transfer relative to rate and direction of motion at night. Observers viewed the lights at a distance of 300 to 500 yards through the windshield of a vehicle parked in the driving lane of an unused road. The vehicle bearing the lights moved back and forth at various rates of speed, directly on the viewer's axis of vision, with little or no lateral movement. Differences were found between the various lights in terms of subject response distributions, apparent illusions of motion, signal to noise ratios within response patterns and error scores. Red lights were generally superior to blue, and monocolor lights were superior to combinations of red and blue in the same light. Twin lights were superior to single beacons, and models with a sequential mirror-generated flash pattern were superior to plain ones. Several of the lights created an illusion of motion when actually at rest. This was most severe for the side-to-side twin light using red lenses. A trade-off was noted between conspicuity and information transfer, in that the lights which were most conspicuous against a road environment background were not those with the best information transfer characteristics. (Author/publisher)
Samenvatting