Pedestrian Conspicuity at Night: How Much Biological Motion is Enough?

Source: Transportation Research Board

"Although earlier research has shown that positioning reflective markers to depict biological motion can dramatically enhance pedestrian conspicuity at night, the mechanisms responsible for this effect remain unclear. In order to determine the effects that the number of reflective elements and natural pedestrian motion have on pedestrian conspicuity, this paper conducted an experiment in open-road conditions. 120 participants were driven along a residential route at night and pressed a button to indicate that a pedestrian was present. Pedestrians, who either stood still or walked in place, were positioned to the right of the roadway and wore either black clothing or black clothing plus 304 cm2 of retroreflective material in one of four different configurations. The mean response distance for the vest condition (23.8 m) was not significantly different from the mean response to the black condition (30.6 m). When pedestrians walked in place, all conditions with markings on the extremities became significantly more conspicuous, with response distances ranging from 88.9 m (ankles) to 113.5 m (biological motion). Although the advantages of marking the extremities were reduced when the pedestrians were standing still, the biological motion configuration (63.2 m) remained significantly more conspicuous than the other conditions. Marking just the ankles was effective only when the pedestrian was walking. These results confirm the conspicuity benefit of placing reflective markings on the major joints of pedestrians and indicate that both form perception and motion perception contribute to this benefit."

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