In this paper, results of an operational study investigating thelegibility distance of unlighted overhead guide signs are presented. Opaque sign backgrounds, as well as engineer, superengineer, and high-intensity reflective sheetings were used in combination with button-removable and high-intensity reflective copy. There was no significant difference between lighted and unlighted signs (lighted, 787.7 Ft; unlighted, 788.1 Ft) by sign material. Several sign combinations performed better than others. Engineer reflective sheeting was legible at more than 900 ft both on the lighted and on the unlighted routes, whereas engineer reflective sheeting with high-intensity stick-on copy was legible at 775 ft (lighted) and 646 ft (unlighted). The following combinations were visible at more than 800 ft: superengineer/button (863 ft), high-intensity/stick-on (825 ft), and superengineer/stick-on (811 ft). This paper appeared in transportation research record no. 1149, Visibility for highway guidance and hazard detection. For covering abstract see IRRD no 817811.
Abstract