design elements - San Jacinto Texas Historic District

Luminaires with various cutoff angles.
IMAGE: SOURCE UNKNOWN
publish the “American National Standard
Practice for Roadway Lighting.” This
document establishes various classifi cations
for roadway, pedestrian walkway, and
bikeway lighting needs. It sets minimum
horizontal light levels (on pavements) and
vertical light levels (on building faces) for
each classifi cation with the goal of mitigating
confl icts between people and cars.
Benefi ts
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Full cutoff fi xtures eliminate direct
contribution to light pollution, light
trespass onto adjacent properties, and
problems with glare.
LED lamps have demonstrated reduced
energy costs of 35-60% compared to
standard high pressure sodium fi xtures.
The life expectancy of LED lamps can
range from 40,000 to 60,000 hours
compared with an average life expectancy
of 24,000 hours for high pressure sodium
and 12,000 hours for pulse start metal
halide lamps.
LED lamps produce whiter appearing
light than high pressure sodium.
LED lamps distribute their light in a more
controlled fashion than other lamps which
can reduce light trespassing issues.
Design & Maintenance Considerations
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Install full cutoff fi xtures without any
uptilt by installing the fi xture on a rigid
mounting arm without an adjustable
knuckle or slipfi tt er.
Full cutoff lighting may require additional
poles and fi xtures overall since the
individual fi xtures do not allow as much
light to be dispersed at shallow angles.
LED lamps are more likely to produce
glare than other lamps. Design to stay
within recommended guidelines for
uniformity ratios (defi ned as average light
level over minimum light level).
The total amount of light (lumens) emitt ed
by LED lamps is often less than other
lamps. This may limit their use in high
volume roadway applications.
Cost Considerations
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Full cutoff lighting can cost as much as
25% more than other types of lighting.
This is directly related to the need for
additional poles and fi xtures because
light does not get distributed as far with
full cutoff fi xtures. The individual fi xtures
cost approximately the same from the
manufacturer as other fi xture types do.
LED lamp fi xtures can cost 10-50% more
than their HPS counterparts.
SAN JACINTO TEXAS HISTORIC DISTRICT CORRIDOR STANDARDS │ 145