In this report a survey is presented of traffic sign visibility problems, visibility of road markings and traffic signals, mainly based on investigations carried out during the seventies in the institute for perception tno, soesterberg, the netherlands. The report is divided into three chapters: properties of the driver, properties of the information carriers, and the influence of external conditions. In the first chapter it is concluded that no test exists which reliably selects the potentially hazardous driver. Apparently, the driver's task is too complicated for such a test. In some detail the following subjects are treated: visual acuity, visual field, colour vision, dark adaptation, night myopia, eye movements, attention, and reading time. The second chapter consists of a discussion of conspicuity, the distinction between signs with text or with symbols and the influence of spacing and stroke width on legibility. In connection with the phenomenon of retroreflection the influence of dew, rain, dirt, and the distinction between the different types of retroreflective materials are treated. Additionally, the subjects of matrix signs, road markings and traffic signals are discussed. In the last chapter the influence of fog, rain and public lighting on visibility of information carriers is surveyed. (Author/publisher).
Samenvatting