ABSTRACT
This chapter describes the minimum candlepower values for all types of retroreflective signs in settings representative of cluttered urban, suburban and dark rural environments. Signs are a primary means of communicating a variety of important and useful items of information to drivers. As a first step in fulfilling this function, signs must come to the attention of approaching motorists reliably, at an adequate distance, and under all reasonable operating conditions. The subjects drove a full-size station wagon, which was equipped with a distance measuring system working off the left-front wheel. The signs were positioned by two assistants, each of whom was responsible for half of the test route. The subjects made six passes through each complexity area. Signs were encountered at random points on each pass at intervals averaging about 1.5 miles. A sign would not typically appear at the same point on succeeding passes.
