The intuitive need for improved sign legibility has increased through the years as traffic volumes, speeds and roadway designs have advanced. Because of increased traffic volumes, low-beam headlight illumination at night has become more imperative. Signs are being located farther from the travelled lanes; higher speeds are requiring messages to be more legible at greater distances (for driver decision and response). Recent studies have indicated that even Engineering Grade (2200 and 3200 Series) Scotchlite or materials designated as Type I, Class A in S.P. No. 89-A, may be inadequate for some signing situations. Signs may be made larger and(or) incorporate materials which are brighter. Thus far, neither brightness nor sign size has exceeded optimum. Obviously, economics and other considerations come into issue.
Digital Object Identifier
Rizenbergs, Rolands L., "High-Intensity Reflective Materials for Signs" (1972). Kentucky Transportation Center Research Report. 921.