Evaluation of Taxiway Guidance Signs

Taxiway guidance signs, 3 feet high and 4 feet wide of a type similar to those used on highways, were evaluated for airport use by means of simulation and actual field trials. Retro-reflective sheeting of red, yellow and green colors was evaluated for color coding application in a taxiway guidance system. Legends, 18 inches in height, were prepared from white enamel and silver retro -reflective sheeting on a red background, black paint on a yellow background and white enamel on a green background. Retro -reflective disc s also were used on the legends for the red and green signs. The discs provided excellent long-range targets but legibility deteriorated as the signs were viewed at distances of 500 to 600 feet and less due to the increased angle from the aircraft light to the sign and the pilot eye, coupled with the white paint appearing black to the observer at these ranges. Tests also were conducted on sign illumination provided by a light source located ahead and below the signs. Test results showed that the signs would provide additional advantageous cues to pilots through means of color coding with (1) red used on the more critical areas such as runway crossings and Category II restricted movement areas, (2) yellow used on all movement areas not requiring red, and (3) green used on and in the vicinity of the apron for informational type guidance such as gate positions and destination identification.