Dobbins JLUS IMP Public Draft Light Pollution Study | Page 52
Measuring Light Output
Light output is measured in various ways. To understand lighting in the
current lighting regulations for each jurisdiction, a brief explanation of how
light output can be measured is provided as follows.
Footcandle Footcandle is an illuminance that equals one lumen
per square foot. One footcandle is equal to
approximately 10 lux (one lumen per square meter).
Lumens Lumens is the unit of measurement used to quantify
the amount of light, or brightness, produced by a
light source.
Wattage Wattage measures the amount of energy a bulb
uses.
Lighting Regulations by Jurisdiction
Cobb County
The Cobb County Zoning Ordinance, Section 134‐275.1 identifies regulations
for the Military Airport Hazard District for the purpose of establishing and
contributing to the safe operations at Dobbins ARB, to facilitate orderly
development around the airfield, to protect property values, and to control
and minimize noise and potential accident impacts on the surrounding areas
of Cobb County and the City of Marietta. As part of this ordinance, in
Section 134‐275‐1.4.4, the Military Airport Hazard District restricts any use
that would make it difficult for pilots to distinguish between airfield lights
and other lights, or that result in glare in the eyes of the pilots using the
airfield or impair the visibility of the airfield. While this supports pilot
visibility, the section is unclear on how this would be accomplished,
particularly for permitted uses.
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For areas outside of the Military Airport Hazard District, and those inside
subject to Section 134‐275‐1.4.4, outdoor lighting is regulated through
lighting plans approved by the County Department of Transportation. The
lighting criteria for the plans are outlined in Section 134‐269. Information
provided must include the location of all proposed lights and nearby County
roads and adjacent properties as well as the arrangement of all poles; height
of poles; number of luminaries per pole; mounting heights of luminaries;
wattage of proposed lights; mounting angle of luminaires; and lamp source
to be used. There are no provisions in the County Code permitting or
restricting temporary outdoor lighting or upward‐directional lighting in any
zoning district.
Sign regulations are included in the Zoning Ordinance. Electronic signs are
defined as a sign that is operated by computer controller, microprocessor
controller, or remote control and uses LED, liquid‐crystal display (LCD),
plasma, or like panels or screen. Per the ordinance, these types of signs are
restricted to nonresidential areas and to a brightness of no more
0.20 footcandles above ambient light as measured at a distance of 125 feet.
The only other restriction for brightness is that electronic signs may not
operate at brightness levels of more than 0.1 footcandles (the illuminance
equaling one lumen per square foot) above ambient light levels if within the
line‐of‐sight of a residentially occupied structure.
City of Marietta
The City of Marietta Zoning Ordinance includes an Air Installation
Compatible Use Zone (AICUZ) Overlay District in Section 712.05. The intent
of this district is to contribute to the safe operations of Dobbins ARB,
facilitate orderly development around the airfield, protect property values,
and to control and minimize noise and potential accident impact
surrounding the City of Marietta. Pursuant to Section 712.05.B.6.c,
development is restricted in any portion of the Overlay District if it will
“produce light emissions, which would either directly or indirectly
DRAFT Dobbins Air Reserve Base Light Pollution Study
March 2018