22 August 2006
Light Pollution / Trespass: The use of fully shielded or full-cutoff
luminaires eliminates direct light above the horizontal plane. While all
lighting contributes to light pollution, direct light has the largest
contribution. Using cut-off optics and low wattage lamps can minimize
light pollution. Shielded luminaires minimize the chance of light trespass
on a neighboring property or building.
Modeling of Faces or Objects: By providing vertical illuminance from
multiple directions, pedestrians' faces will be visible and accurately
Peripheral Detection: Detecting hazards relies heavily on peripheral vision.
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.
Reflected Glare: Consider the potential for reflected glare based on
luminaire location and surface characteristics.
Shadows: Locate luminaires to eliminate shadows that could hide
Vertical Illuminance: Adequate vertical illuminance lights possible hazards
as well as other pedestrians.
Target Horizontal Illuminance ( 10%): 5 lux (0.5 fc)
Pedestrian walkways using a pedestrian scale poles allow for adequate vertical
illuminance to light individuals and their faces. If the luminaires are decorative, a lens or
louver should shield the lamp, prevent direct glare, and minimize the possibility of light
trespass. Eliminating glare and providing uniformity provides the best security lighting.
Low wattage lamps and shielded or cut-off luminaires minimize light pollution.
Locate poles in paved areas when possible to avoid blocking irrigation spray heads.
When luminaires are positioned in planting areas, locate in shrub rather than lawn areas
to avoid damage from mowing and edging.
RULES OF THUMB:
Mounting Height: Use 3.0 4.3 m (10 14 ft) poles for pedestrian
Spacing to Mounting Height: When beginning a design, start with an 8:1
spacing to mounting height ratio and modify accordingly to meet critical
Locate Poles at Intersections and Nodes. Consider the visual layout of
equipment rather than a strict adherence to spacing criteria.