TM
5-811-1/AFJMAN
32-1080
CHAPTER 10
ROADWAY AND AREA LIGHTING
10-1. General.
but will not exceed 25 percent of the mounting
height. Light distribution characteristics of any
Quantity and quality of illumination will conform
luminaire will suit the mounting height, road
to the latest issue of the Illumination Engineering
geometry, and uniformity required. Vertical and
Society's (IES) Lighting Handbook, except as modi-
lateral light distribution and control of these
fied in this chapter. Data contained in IES RP-8
characteristics will be indicated for each lumi-
provides a basic reference relating to the princi-
naire.
ples of standard roadway lighting practice. Unless
(1) Vertical. Vertical light distributions, based
otherwise indicated, illuminances are always on
on spacing-to-mounting height ratios, are catego-
the horizontal plane at ground level. Where di-
rized as short, medium, and long distribution.
rected, illuminances will be modified to be in
Short distribution is suitable for pole spacings no
greater than 4.5 times the mounting height; me-
conformance with current energy conservation pol-
icies.
dium distribution is suitable for pole spacings from
4.5 to 7.5 times the mounting height; and long
10-2. Roadway lighting Design.
distribution is suitable for pole spacings from 7.5
a. Illuminances. The average maintained hori-
to 12 times the mounting height. Medium distribu-
tion is the most appropriate choice for the mount-
zontal illumination recommended by IES is based
ing heights and spacings utilized on military
on the type of traffic flow and the character of the
surrounding area. On military installations, the
installations.
(2) Lateral. Lateral (transverse) light distribu-
values for road and area classification used will
tions, based on the shape of the half candlepower
range from 4 lux (0.4 footcandles) to 13 lux (1.3
footcandles). Luminaires located along roadways
isocandela trace which falls within the longitudi-
nal distribution range, are classified as Types I
and intersections at spacings ranging from 150 to
200 feet can provide illumination within this
through V. A general guide to their use, compiled
from date in IES RP-8, is shown on figure 10-2.
range as shown in table 10-1. The definitions of
the IES classifications in table 10-1 can be found
Selection is dependent upon whether the luminaire
in the current IES Lighting Handbook. Spacings
is situated at the side or at the center of the road,
whether the luminaire is located between intersec-
are approximate and may vary somewhat depen-
tions or at an intersection, and the roadway width.
dent upon the actual luminaire type, mounting
Since most luminaires are mounted at the side of
height, roadway width, and other conditions apply-
ing. Lux and footcandles are related by an approx-
the road, Types II, III, or IV are used more often.
imate 10-to-1 factor.
Type II is used to light narrow roads, and types III
b. Luminaires. Luminaires of the enclosed type
and IV are used for lighting progressively wider
utilizing high-pressure sodium (HPS) lamps will be
roadways.
(3) Control. Control of the amount of light in
used. A discussion of the characteristics of various
the upper portion of the beam above maximum
light sources is presented later in this chapter.
Figure 10-1 indicates a typical roadway lighting
candlepower is classified as cutoff, semicutoff, or
noncutoff. Semicutoff limits the lumen output
installation. Bracket length is dependent upon the
above the nadir to 5 percent at 90 degrees horizon-
location of the luminaire and the roadway width,
Table 10-1. Illumination Versus Spacing.
HPS
IES Classification
a
lux
lamp
Spacing
Area
Road'
feetb
(footcandles)
wattage
Residential
100 . . . . . . . . . . . . . . . . . . . .
Local . . . . . . . . . . . . . . . . . .
4(0.4) . . . . . . . . . . . . . . . . . . . 170 . . . . . . . . . . . . . . . . . . . .
Intermediate
9(0.9) . . . . . . . . . . . . . . . . . . . 200 . . . . . . . . . . . . . . . . . . . .
250 . . . . . . . . . . . . . . . . . . . .
Collector . . . . . . . . . . . . . . .
Intermediate
13(1.3). . . . . . . . . . . . . . . . . . 150.. . . . . . . . . . . . . . . . . . .
250 . . . . . . . . . . . . . . . . . . . .
Major . . . . . . . . . . . . . . . . . .
a
Required average maintained illuminance, with a uniformity ratio meeting IES requirements.
b
Based on units mounted 30 feet above the roadway on the same side. For intermediate areas, road width is assumed to be 40
feet and for residential areas to be 30 feet.
c
Based on R3 pavement classification.
10-1
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