The Legibility of the Clearview Typeface System Versus Standard Highway Alphabets on Negative- and Positive-Contrast Signs

Garvey, Philip M.; Klena, M. Jennifer; Eie, Wei-Yin; Meeker, Donald; Pietrucha, Martin T. · 2015 · ROSA P / Mid-Atlantic Universities Transportation Center

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Summary

This study evaluates the legibility of the Clearview Typeface System compared to Standard Highway Alphabets on negative-contrast (black-on-white) and positive-contrast (white-on-green) highway signs. Motivated by the Federal Highway Administration’s (FHWA) 2004 interim approval of Clearview for positive-contrast guide signs and a request to extend research to negative-contrast applications, the researchers aimed to determine if Clearview offers similar legibility improvements for regulatory and warning signs. The study also assessed the impact of inter-letter spacing, letter height, and driver age on reading distances. The research was conducted at the Thomas D. Larson Pennsylvania Transportation Institute at Penn State using a controlled test track. One hundred fourteen licensed drivers, categorized into younger (18–34), middle-aged (35–64), and older (65+) groups, participated in daytime and nighttime trials. Subjects drove at 15 mph toward signs mounted at standard heights and recorded the maximum distance at which they could correctly read the text (legibility threshold). The experiment compared mixed-case Clearview (weights 2-B, 3-B, 4-B) against mixed-case and all-uppercase Standard Highway Alphabets (Series C, D, E). Variables included standard and reduced inter-letter spacing, and capital letter heights of 6.0 inches and 4.8 inches. A supplementary survey of state and local Department of Transportation agencies assessed current usage and willingness to adopt negative-contrast Clearview. Results indicated that for negative-contrast signs, standard inter-letter spacing yielded the longest legibility distances. Mixed-case Clearview performed equivalently to all-uppercase Standard Alphabets but significantly outperformed mixed-case Standard Alphabets, particularly for Clearview 3-B and 4-B. Reducing Clearview letter height to 4.8 inches resulted in legibility distances equivalent to 6.0-inch mixed-case Standard Alphabets, suggesting potential space savings. For positive-contrast signs, 6.0-inch Clearview significantly outperformed comparable Standard Alphabets, and 4.8-inch Clearview matched the performance of 6.0-inch Standard Alphabets. Legibility distances were consistently shorter at night and for older drivers. However, statistical significance for older drivers was limited; while mean distances favored Clearview, only specific comparisons (e.g., Clearview 4-B vs. Series E) reached significance. The DOT survey revealed that 64% of responding agencies use positive-contrast Clearview, with generally positive feedback, though only 30% expressed inclination to use negative-contrast Clearview pending further approval and evidence. The findings suggest that Clearview offers legibility advantages over mixed-case Standard Alphabets in negative-contrast applications and maintains its superiority in positive-contrast settings. The ability of smaller Clearview fonts to match larger Standard fonts implies potential efficiency in sign design. While older drivers showed improved mean legibility with Clearview, the lack of broad statistical significance highlights the need for further research into recognition tasks and specific design variables to fully validate benefits for aging populations. The study provides critical data for FHWA and state agencies considering the expansion of Clearview usage to regulatory and warning signs.

Key finding

Mixed-case Clearview typefaces on negative-contrast signs provided significantly longer legibility distances than mixed-case Standard Highway Alphabets, while 6-inch Clearview typefaces on positive-contrast signs outperformed comparable Standard Alphabets.

Methodology

on_road

Sample size: 114

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