A brightness inventory of contemporary signing materials for guide signs. Paper resented at the 50th Annual Meeting of the Highway Research Board HRB, Washington, D.C., January 1971.

The brightness of contemporary sign materials on guide signs as seen by the driver in both day and night viewing conditions has been measured. The readings were made at several distances and under both high-and low- beam illumination. The measured results are presented for a variety of sign materials in common use. Discussions of the paper as well as authors' closure are included. (See also PB 466 for preprint of paper).