LED Street Light Research Project

The revised approach became one of recommending specifications
for business district LED fixtures that would:
› Meet all new Lighting Ordinance requirements
› Improve on the LED fixtures already in place in Pittsburgh
As the City’s LED street lighting program would be implemented
over a period of several years, it was understood that a more
rigorous design and testing of LED fixtures, certification of appropriate
fixtures, and recommended LED revisions to the Lighting
Ordinance would follow this initial research as a Phase II project.
Recommendations
Initial recommendations for new business district street lighting
and fixtures are in three forms:
8. General criteria that convey the design and performance
intent of business district LED street lighting
9. Base performance criteria for new LED fixtures, including photometrics,
color, controls, and design
10. Evaluation criteria for a simplified testing procedure of
manufacturer-submitted fixtures as part of the bidding selection
process
In addition, upgrade recommendations are made for additional
controls and accessory wayfinding lighting. With the exception of
the additional controls and wayfinding recommendations, these
formed the basis for the City’s solicitation of 3,100 LED fixtures
for 30 of the city’s business districts as Phase 1 of the LED street
lighting program.
The findings generated from the research modified the City’s
original intentions for the Phase 1 program. Originally the intention
was to replace only the lamps with new LED arrays and
retain the fixture housings and lenses. Because of the existing
September 2011
fixture housings and reflector designs specifically for HID lamps,
not LEDs, and the inability of the acorn fixture to control lighting
spread, the RCI research team recommended and the City agreed
to replace the entire fixture with LED-appropriate fixtures and to
consider other fixtures to replace the acorns. The value of electronic
controls for monitoring and addressing individual fixtures
was recognized as a desired feature and City requested that the
recommendations also include a control-ready requirement in the
base criteria for all new LED fixtures.
Technical and Aesthetic Performance for Business District
LED Lighting
The performance of these luminaires is intended to be superior
to the performance of the HID luminaires they are replacing. This
is true in terms of energy consumption, but is also true in terms
of visibility, glare, and more accurate color rendition. Within the
criteria that are noted below, the intent is to benefit from better
lighting performance and multiple tasking of street lighting, with
the assumption that street lights should “illuminate but not be
seen.”
Although LED lighting can be very even, it is the intent of these
recommendations to comply with the City’s lighting regulations at
the lowest acceptable evenness ratio in order to control for glare
and visual clarity.
General Criteria
› Luminaires for LED replacement are existing business district
cobra head, teardrop, shoebox, acorn, and globe luminaires.
› The entire luminaire head is to be replaced, not just the HID
lamps. The luminaire is to attach to existing pendants or poles
similar to existing cobra head, teardrop, shoebox, acorn and globe
Pittsburgh LED Street Light Research Project 85