Legibility of the Clearview Typeface and FHWA Standard Alphabets on Negative- and Positive-Contrast Signs

The main objective of this research was to compare the legibility distance of the negative-contrast Clearview typeface with that of comparable FHWA Standard Alphabets on black-on-white signs in the daytime and nighttime for older and younger motorists. Mixed-case Clearview (2-B, 3-B, and 4-B) was compared with both mixed-case and uppercase FHWA Standard Alphabets (Series C, D, and E). In addition, the researchers evaluated the effects of letter height on the legibility distance of mixed-case Clearview. A small set of positive-contrast white-on-green signs were displayed to compare Clearview Typefaces 2-W, 3-W, and 4-W with FHWA Standard Alphabet Series C, D, and E, which are all mixed case. Overall, signs that used Clearview negative-contrast in mixed case performed as well as FHWA Standard Alphabets in uppercase (even though the Clearview fonts took up less sign space than the FHWA Standard Alphabets) and better than mixed-case FHWA Standard Alphabets in both daytime and nighttime. Overall, Clearview in positive contrast (white on green) outperformed the comparable FHWA Standard Alphabets. In addition, a survey conducted with state departments of transportation of their current use of Clearview in positive contrast and their potential use of Clearview in negative contrast is discussed.