Previous research evaluated the use of unassigned sign colors from the "Manual on Uniform Traffic Control Devices" for incident management trailblazing; however, fluorescent sign colors were not evaluated. Since evidence suggests that fluorescence on signs improves conspicuity, the following colors were evaluated along a contrived test route with an instrumented vehicle: black on fluorescent coral, fluorescent yellow on fluorescent purple, black on fluorescent yellow-green, and yellow on purple in nonfluorescent colors. No significant differences in driving performance were exhibited among the four experimental sign-color combinations. Based on questionnaire results, the black on fluorescent yellow-green sign was preferred by younger and older drivers during both day and night visibility conditions. However, fluorescent yellow-green was subsequently assigned by the Federal Highway Administration for pedestrian, school, and bicycle crossings. For the remaining colors, black on fluorescent coral was ranked highest for visibility and overall preference, followed by fluorescent yellow on fluorescent purple, with nonfluorescent yellow on purple least preferred. Black on fluorescent coral was preferred over fluorescent yellow on fluorescent purple during daytime viewing conditions, while the reverse was true for nighttime. Drivers also commented that the arrow on the sign was too small to determine directional information from a comfortable distance.
Abstract