Improvement of conspicuity of trailblazing signs, Phase III : evaluation of fluorescent colors.

Neale, Vicki L · 2001 · ROSA P / Virginia Transportation Research Council (VTRC)

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Summary

This study, Phase III of a series on improving the conspicuity of trailblazing signs for incident management, addresses the need for a unique sign color distinct from standard construction signage. Previous phases identified limitations in existing color schemes, particularly the confusion caused by using black-on-orange signs for both construction and emergency detours. This phase specifically evaluated fluorescent colors, which laboratory research suggested could enhance visibility, to determine if they offered superior conspicuity for drivers navigating unfamiliar diversion routes. The researchers employed a 4 x 2 x 2 between-subjects experimental design, testing four sign color combinations: black on fluorescent coral, fluorescent yellow on fluorescent purple, black on fluorescent yellow-green, and non-fluorescent yellow on purple (as a baseline). The study involved 91 drivers, categorized into younger (18–34 years) and older (55+ years) groups, who drove a 19.6 km route in Montgomery County, Virginia, during either daytime or nighttime conditions. Data collection utilized an instrumented vehicle to record objective driving performance metrics, including late braking reactions and navigation errors (wrong or missed turns). Additionally, participants completed post-drive questionnaires to assess subjective preferences regarding visibility, readability, and overall acceptance of the sign colors. The results indicated no significant differences in objective driving performance among the four experimental sign color combinations. However, subjective preference data revealed distinct trends. Black on fluorescent yellow-green was the most preferred color by both younger and older drivers during both day and night conditions. Nevertheless, this color was eliminated from consideration because the Federal Highway Administration had reserved it for pedestrian, school, and bicycle crossings. Non-fluorescent yellow on purple showed increased preference at night but lower overall preference compared to the fluorescent options. Between the remaining contenders, black on fluorescent coral was ranked significantly higher than fluorescent yellow on fluorescent purple for visibility and overall preference. Trend analysis suggested black on fluorescent coral was preferred during daytime, while fluorescent yellow on fluorescent purple was preferred at night. Drivers also noted that the directional arrow on the signs was too small to be read comfortably from a distance. Based on these findings, the authors recommend adopting black on fluorescent coral as the unique sign color for incident management trailblazing. They also recommend increasing the size of the directional arrow to improve legibility. The study concludes that while fluorescent materials offer potential benefits, regulatory constraints and subjective preferences must guide the final selection to ensure the sign is both unique and acceptable to the driving public.

Key finding

Black on fluorescent coral was ranked significantly higher than fluorescent yellow on fluorescent purple for visibility and overall preference, and was recommended as the unique incident management sign color.

Methodology

naturalistic

Sample size: 91

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• sign visibility legibility
• vehicle conspicuity
• emergency work zone conspicuity
• vru conspicuity
• signage environment
• roadway lighting effects