22 August 2006
Shadows: Locate and select luminaires to provide a uniform illuminance
on the ground and eliminate dark spots and shadows. Such dark spots
can be distracting to drivers and also may conceal hazards.
Vertical Illuminance: Pole location, height, and luminaire selection all
contribute to adequate vertical illuminance.
Target Horizontal Illuminance ( 10%): Varies with type of surrounding
Research shows that peripheral vision and detection are enhanced under white light.
White light (as opposed to more orange light produced by high-pressure sodium)
renders objects sharper and provides excellent peripheral detection compared to high-
pressure sodium. This peripheral detection is critical at points where other vehicles may
be entering a roadway and pedestrians may be crossing the street.
In addition to providing better visibility, this has an energy impact as well. The same
visibility can be provided with a lower level of white light that would require a higher
level of HPS light.
and light trespass.