Performance of signs under dew and frost conditions. Paper prepared for the 57th Annual Meeting of the Transportation Research Board, Washington, January 16-20, 1978.

A common cause of loss of signing conspicuity (target value) and clarity at night is light scattering from droplets or dew or crystals of frost on retroreflective signing materials. The relative performances of a number of available combinations of signing materials were subjectively examined under natural dew and frost conditions. The performance of all combinations of sign materials appeared to be less affected by frost than by dew.