Development of Road Lighting Technology and Dimensioning
The results show that in road and street lighting conditions the light level has a strong effect on the visibility of moving targets. The effect of light spectrum is not linear in different parts of the visual field. Light spectra did not affect visibility when the target was viewed foveally. At lower mesopic levels differences in peripheral visibility were found between light spectra.
The findings suggest, that the conventionally used HPS lamps are not necessarily the most optimal light sources for low luminance levels of street and road lighting. Light sources with higher content in the blue wavelength region may be more optimal for visual performance especially in street lighting applications, where the dimensioning levels are low. The use of e.g. metal halide lamps in street lighting of city areas may also be justifiable because of the better colour properties of this lamp type.