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

摘要

The main objective of this research was to compare the legibility distance of the negative-contrast (i.e., darker letters on a lighter background) Clearview Typeface System with that of comparable Standard Highway Alphabets on black-on-white signs in the daytime and nighttime for older and younger motorists. Mixed-case Clearview was compared to both mixed and all-uppercase Standard Highway Alphabets Series C, D, and E. (Mixed-case words have an initial capital letter followed by all lower-case letters. All uppercase words are the standard condition of regulatory, warning, and work zone signs.) These typefaces were selected for study, as they are the most commonly used typefaces in negative-contrast applications. In addition, the researchers at the Thomas D. Larson Pennsylvania Transportation Institute at Penn State evaluated the effects of inter-letter spacing and letter height on the legibility distance of mixed-case Clearview 2-B, 3-B, and 4-B. A small set of white-on-green (positive contrast) signs were displayed as well, comparing Clearview Typefaces 2-W, 3-W, and 4-W with Standard Highway Alphabet Series C, D, and E, all in mixed-case. This research was planned as Part 1 of a three-part study effort into the readability of negative-contrast highway signs. Part 1 would identify the relative legibility of various typefaces and mixed versus all uppercase words. Part 2 would address recognition, or the understanding of messages, using various typefaces in both uppercase and mixed case. Part 3 would address figure/field and format to learn how display variables may enhance sign readability.