This project focused on the evaluation of traffic sign sheeting performance in terms of meeting the nighttime driver needs. The goal was to develop a nighttime driver needs specification for traffic signs. The researchers used nighttime sign legibility and eye-tracker data to assess the performance needs of nighttime drivers on a closed-course facility as well as on the open road. The researchers also used internally illuminated signs during the research to control the sign luminance (rather than being constrained to the luminance curves provided by the retroreflective sheeting materials on the market). Using the results of the nighttime legibility and eye-tracker studies, the researchers developed a classification scheme for retroreflective sheeting materials based on luminance requirements derived from the study. Then the researchers modeled the retroreflective geometries resulting from common roadway scenarios (sign position, roadway type and cross-section, vehicle size, etc). Using the luminance requirements derived from the study and market-weighted headlamp flux matrices, the researchers developed an approach to sign sheeting specification that is based on nighttime driver needs. (Author/publisher)
Abstract