Figure 6-17.Utilization curve
Streetlighting systems usually give lighting
Figure 6-18.Streetlight layout.
intensity from .01 to 0.5 footcandle; however, this
value is too low for any night activity requiring good
visibility. Figure 6-21 gives recommended
illumination intensities for specific night activities.
The following suggestions should be followed to
improve the efficiency of floodlighting systems:
Select floodlight locations so beams strike the
The minimum point footcandies are
fc min = (0.03) (50) (0.70) (0.56) = 0.58
Therefore, the average-to-minimum ratio of uni-
formity would be
surface to be illuminated as nearly perpendicular as
When lighting irregular surfaces, use two or
more floodlights to reduce sharp shadows caused by
A uniformity ratio of 3.40 meets the ANSI/IES
recommended roadway illumination levels (table 6-1)
for a major, commercial roadway.
For lighting extended horizontal surfaces, such
as work areas, mount floodlights high enough to