This Lighting Measurements Guide provides test procedures and methods of obtaining and reporting data that promote evaluation of the photometric nighttime performance of roadway sign installations in a logical and uniform manner. It revises and replaces the previous edition last published in 1985. This Guide generally applies to all roadway sign installations using an integral lighting system. These signs may be externally illuminated, utilizing nontransparent (not translucent) surface materials (legend, border, and background); or, they may be internally lighted, utilizing translucent sign materials. This Guide does not address the measurement and evaluation of luminous source message signs (matrices of individual lamps or other luminous elements making up a message). In the context of this Guide, retro-reflective sign materials are considered only in so far as they yield luminance values due to their fixed lighting systems.