It is important that road signs be easily visible at night. The Federal Highway Administration is currently conducting research on the visibility of signs at night. This research began in the 1980s. The studies examine how much light signs need to reflect for drives to see them at night. Key components of the study include performing field studies of drivers' nighttime visibility needs, developing a computer model for calculating minimum retroflectivity levels and conducting workshops to improve training efforts. Researchers found that drivers need more light as they age. Research also shows that retroflectivity has improved significantly in recent years, and that vehicle headlamp styles are changing, necessitating an evaluating of signs' ability to reflect these new styles. Results of the study indicate that new types of headlamps do not help improve visibility. Thus, the onus falls on sign designers to ensure visibility.
Abstract