Maximizing Legibility of Unlit Freeway Guide Signs with Clearview Font and Combinations of Retroreflective Sheeting Materials

Abstract

The legibility of full-scale guide signs was evaluated in a controlled field study. The objective was to determine how the legibility of unlit guide signs could be maximized with combinations of font and retroreflective sheeting. Two fonts were tested: Series E (Modified) and Clearview 5WR, a modified version of Clearview 5W. Five combinations of retroreflective sheeting were also evaluated. The study included 30 subjects split into three age groups. Without informing the subjects, the researchers varied headlamp output to evaluate the legibility of various sign lighting levels. The results of the study clearly show that the most legible combination of font and retroreflective sheeting (of those tested) is the Clearview 5WR font and microprismatic legends on beaded, high-intensity backgrounds. Although the combination of microprismatic legends and backgrounds performed statistically equivalently to microprismatic legends on beaded, high-intensity backgrounds (in term of legibility distances), the research shows that the higher luminance contrast and lower costs associated with the latter combination make it a much more attractive application.