Evaluation of the Clearview Font for Negative Contrast Traffic Signs

Texas Department of Transportation (TxDOT) sponsored research has shown that the Clearview font provides longer legibility distances than the Highway Gothic font Series E (Modified) when used on freeway guide signs with positive contrast of white letters on a dark background. Additional studies have shown that Clearview outperforms other versions of Highway Gothic fonts on other, smaller types of guide signs. These results have helped support the adoption of the Clearview font into the Federal Highway Administration¿s (FHWA) Standard Highway Signs book. The Clearview font has been developed with two sets of fonts¿one for positive contrast signs and another for negative contrast signs. Prior to this research project, there were no studies documenting the performance of the Clearview font for negative contrast signs such as those found in the regulatory and warning sign series. This research project evaluated the negative contrast Clearview font in black letters on fluorescent yellow, fluorescent orange, and white backgrounds. The researchers performed a laptop-based presentation survey and a closed-course field study. The laptop survey used static, in-context sign images to compare sign fonts. The field study was a dynamic recognition and legibility test using full-sized retroreflective signs during the day and at night. The field study compared the standard font to three treatments of the Clearview font. The results of this research project show that the Clearview font provides the same performance as the current FHWA font series for negative contrast traffic signs with the exception of the nighttime recognition. In this instance, the straight replacement of Clearview did not achieve similar recognition distances as the FHWA font series until the stroke width was increased to the next weight. The recognition distance provided by traffic signs can be considered one of the most critical measures of effectiveness when assessing sign performance. Therefore, because there were no statistically significant increases in recognition or legibility distances for any of the Clearview fonts tested, and because the results of the nighttime recognition analysis showed a decrease in recognition distance when the FHWA font was replaced with the Clearview f ont, the researchers recommend that TxDOT continue using the FHWA font series for negative contrast signs.