Perception of Pedestrian Traffic Signals by Pedestrians with Varying Levels of Vision

Abstract

This study evaluated the usability of pedestrian signals by persons with varying visual acuities under different conditions of symbol size, crossing length, and type of background behind the signals. While viewing photographs presented on a computer monitor under unimpaired viewing conditions (approximately 20/20 visual acuity) and under simulated visual impairment (approximate acuities of 20/100 and 20/300), participants attempted to determine the pedestrian phase (“Walk” or “Don't Walk”) and to report the number presented by the countdown timer display. Performance on the phase discrimination task by those with simulated 20/300 acuity and with symbols 9 and 12 in. high often was little better than chance despite a highly controlled environment (i.e., no moving vehicles or environmental distractions) and signals that were subjectively determined to be in excellent working condition and of high visibility (i.e., good luminance–contrast, no glare). Reading the countdown display was essentially impossible. Participants with simulated 20/100 acuity were rather successful in phase identification, and they averaged more than 87% correct under all stimulus conditions. But room for improvement existed compared with performance under 20/20 conditions. Reading the countdown display was difficult for participants with simulated 20/100 acuity; they averaged between 6.5% and 58.5% correct under the various stimulus conditions. The effect of different backgrounds on the usability of the signals, as well as the implications of the findings about signal size and crossing length on the current signals standards, are discussed.