The following terms shall have the indicated
meanings:
CANDLE-POWER DISTRIBUTION CURVE
A curve representing the variation of luminous intensity
of the luminaire, measured in candelas in a plane through a light
center.
CUT-OFF LIGHT DISTRIBUTION
Light distribution for a luminaire such that candle power
per 1,000 lumens does not exceed 25 (2.5%) at 90° above nadir
or 100 (10%) at 80° above nadir at any location around the luminaire.
The cut-off classification is usually specified on the manufacturer's
published data.
DRIVEWAY ACCESS
A usable roadway suitable for vehicular traffic connecting
private buildings, parking areas and other facilities to public streets
and roads.
GLARE
The sensation produced by luminance sufficiently greater
than the luminance to which the eye is adapted so as to cause annoyance,
discomfort or loss in visual performance and visibility.
ILLUMINANCE
The density of light on a surface quantified in foot-candles,
measured by an illuminance meter or calculated by accepted engineering
techniques.
LEVEL OF ACTIVITY
Classification by the number of vehicles and level of pedestrian
activity in the area.
LIGHT DISTRIBUTION
The illuminance at all points on the illuminated surface
from specified light sources at specified mounting heights and spacing.
LIGHT TRESSPASS
The unwanted lighting of neighboring properties from light
sources intended for the proposed sites.
LUMINAIRE
A complete lighting unit consisting of a light source and
all necessary mechanical, electrical and decorative parts.
MOUNTING HEIGHT
The vertical distance of the light source from the illuminated
plane.
SPACING
The horizontal distance between adjacent light sources.
Lighting requirements for an outdoor area depend on the level of usage the facility is anticipated to receive. Table 1 in §
220-48.14 establishes four levels of activity, which correspond to the level of traffic and pedestrian activity. Each includes a broad range of activities. For activities not included in Table 1, the Planning Board, in consultation with the applicant, will assign a level consistent with the expected activity on the site.
Table 2 in §
220-48.15 includes illuminance recommendations for open parking facilities and driveways. These recommendations provide for the safe movement of traffic, for satisfactory vision for pedestrians and for the guidance of both vehicle operators and pedestrians. The illuminance levels are the lowest acceptable, consistent with the seeing task involved and the need to deter vandalism while meeting energy conservation constraints.
A. Light distribution. Illuminance is affected by interrelated
factors such as the characteristics of the specified light sources,
mounting heights and spacing. These and other factors must be chosen
so that illuminance meets the guidelines specified herein without
causing glare or light trespass.
(1)
General lighting. Luminaries for general area
lighting, whether pole- or wall-mounted, shall have cut-off light
distribution. Spotlights and floodlights shall not be used for general
lighting. Where supplementary lighting is desired (for example, for
building or sign illumination) the luminaires should be properly shielded
to avoid light trespass and glare.
(2)
External sign lighting. Where illumination of
freestanding signs is desired, the illuminator shall be chosen to
avoid glare in the area below and around the sign. If necessary, the
sign shall be constructed of opaque panels or surrounded by dense
shrubbery from the lower edge of the sign to the ground.
(3)
Mounting height of luminaires. Mounting heights
of luminaires, whether pole- or wall-mounted, shall be limited as
follows:
(a)
For development projects subject to site plan
review in the RR-80, RR-40, R-1, R-2, R-3, R-P and L-C Zoning Districts,
maximum mounting heights shall not exceed 20 feet.
(b)
For development projects subject to site plan
review in the C-N Zoning District, maximum mounting height shall not
exceed 22 feet.
(c)
For development projects in the C-H, C-S, I-G
and I-R Zoning Districts, maximum mounting height shall not exceed
30 feet or the roof line of the building, whichever is less, except
that mounting height for lighting located within 50 feet of a residential
property line shall not exceed 20 feet.
(d)
For development projects subject to site plan review in the Town Center Overlay District, see §
220-48.5C(3).
B. Minimum illuminances for general parking and pedestrian
areas. Minimum footcandles have been specified for the general parking
and pedestrian areas because an absolute minimum of lighting is necessary
for the identification of features for pedestrian safety. Levels should
not be lower than the recommended minimum at any point.
C. Minimum levels for driveway access. Minimum footcandles
have been specified based on the assumption that separate walkways
are provided for pedestrian activity. Where mixed pedestrian and vehicular
traffic is anticipated, higher levels of illuminance should be provided.
D. Illuminance at entrances. Illuminance at entrances
from public roads to private parking areas and private access driveways
must be adequate for vehicle operators to recognize entrance details,
to decelerate and to safely leave the traffic stream.
(1)
Glare and excessive contrast between public
road and private areas should be avoided.
(2)
Typical entrance illuminance levels are 0.5
to 2.0 footcandles.
E. Maximum illuminance at property lines. At the property
line of the subject property, illumination from luminaires shall not
exceed 0.1 footcandles on residential property or 0.5 footcandles
on nonresidential property, as measured on a vertical plan.
F. Energy management. Under certain circumstances it
may be desirable to reduce the lighting levels during periods of reduced
activity. For example, during peak use, the "high" activity lighting
level may be required. During inactive periods, where level of activity
is in the "low" classification, only security lighting might be required.
G. Neighborhood consideration. Within the requirements
of public safety, new lighting shall avoid nuisance to neighborhood
properties and shall not have adverse effect on the character of the
area as defined by zoning regulations.
If strict adherence to this policy results in
conflict, the Planning Board may, at its discretion, modify specific
requirements to achieve balance among competing requirements.