A standard practice on the nighttime performance of retroreflective sign sheeting performance used on traffic signs through viewing scenarios has been developed and is expected to be published soon. The committee determined that a supplementary guide will be needed to aid the practitioner in using this standard practice and help ensure that they are educated and competent about the practice and accurate in interpreting its output. Sign sheeting is only one variable in the practice, and the user should understand the intent and scope of the other variables to determine the best set of scenarios that suit their needs. Such variables include headlamp percentiles, vehicle types and mixes, sign placements, letter sizes and variables that are correlated with letter size, and the effect of visual complexity. The standard guide will elaborate on these variables, their interactions with each other, and their correlations with other variables that were outside the scope of the standard, helping the user make an informed decision on the representative scenarios and provide an accurate perspective on the output of the practice.
The title and scope are in draft form and are under development within this ASTM Committee.