The widespread use of retroreflective materials for information, regulation, and warning signs and the inclusion of retroreflective materials in many official standards suggest that a framework of luminance standards for minimum visual performance be adopted. Such a construct assumes that a variety of signing materials are available from which predictions of performance may be made. A methodology is provided to compare signing materials in a variety of placements, road geometries, and distances for existing types of retroreflective materials. The study compares the performance of retroreflective materials for existing headlamps and under many circumstances of use. Information is also provided on allowances for such factors as complex nighttime surroundings, the unalerted driver, and the relative importance of sign priority.