Abstract
This paper presents additional data on seeing factor effec tiveness ratings for roadway lighting. Such ratings provide an essential basis for highwat engineering evaluation of traffic, economic, and human benfits. Field measurements for different roadway lighting systems are continuing, are significant, and should be reported for the guidance of highway eng&neers interes- ted in imp.oving night motor vehKicle transportation. Preliminary test show that about twice as much pavemetn brightness is required for equivalen L+M visibility when the target is dynamic instead of static.This is based on ratings by eight observers.