In dense fog, adequate visibility of the delineator is important for providing the driver with road geometry cues. The present study proposes an illuminated delineator that uses fibre optic (FO) delineator. Although FO delineators can be expected to have good visibility in dense fog due to their high intensity and low scattering effect, there have been few studies dealing specially with this. Therefore, this study was conducted to evaluate the visibility of FO delineators in fog. The effectiveness of brightness and colour on the visibility of FO delineators was investigated in artificial fog. The dependent variables were luminance at the whole front face of the FO delineator and subjective visibility of the FO delineator. The major independent variables were fog, density, illuminance (0lx) and 2000 lx) in the observation room, brightness level of the FO delineator, and colour of the FO delineator. The FO delineator was observed as a sharp point set in dense artificial fog. The FO delineator provided sufficient visibility distance in dense artificial fog. Colour had less effect than brightness level on the visibility of the FO delineator. A highly scattered luminance was not generated in dense artificial fog if brightness of the FO delineator was maximised. On the basis of these results, it is concluded that FO delineators can provide good visibility in dense fog both in the daytime and at night time. (A)
Samenvatting