Wednesday, March 28, 2018

"2700 K" is Big News for Street Lights

    The new Director of the District Department of Transportation (DDOT) has announced an important policy shift for the future of all of the city's 71,000 street lights. If carried out,  the policy could keep more of the historic character of Washington's streets and avenues when the new lighting infrastructure is rolled out. The change would be good for residents' health, too!

    Director Jeff Marootian spoke about DDOT's street light conversion at the meeting of Sheridan-Kalorama Advisory Neighborhood Commission 2D on March 19, using a technical term for the color temperature of the new Light Emitting Diode (LED) lights.

   "My goal is to go to 2700 Kelvin in many places, if not all places, in DC."

    Visible light has different "colors" depending on the wavelength. Street lights shine at different "color temperatures" depending on technology. DC's  present system of incandescent and high pressure sodium street lights glow in amber tones about 1900 to 2100 Kelvin. But they suck up many times the power of new LED lights.  

    In the photo below you see DC's amber-hued high pressure sodium lights on the west side of 18 Street where it crosses Mass Ave NW.  On the east side of 18 Street (at left, where guide Bonnie Garrity is pointing) you see a 4000 Kelvin LED.  (The photo was taken during RMA's  February 21 Street Light Tour. See Tour Slideshow for more. )

    Most cities are converting to LED street lights to save on power. Also a modern light system includes other "smart city" services like local light controls, wi-fi and monitoring of traffic (the latter prepares for driverless vehicles).  In his remarks to the ANC, Director Marootian stressed that technology for these systems is moving very fast and he hopes the District will be at the forefront.
    But the city began planning its move to low-power LED lights years ago. For much of the last decade, a higher blue-white color temperature was associated with safety.   Some cities such as Milan, Italy installed blue-white LEDs throughout. In the District DDOT began installing 4000-5000 Kelvin lights in alleys and elsewhere. 

    A DDOT pamphlet on the modernization program, some years ago, said that by 2014 most lights would be 4000 Kelvin.
   But the American Medical Association issued a report in 2016. (1) It warned that high color temperature street lights interfere with human melatonin, which naturally prepares our bodies for sleep. Pollinators get confused by these lights; they also interfere with plant growth. Their glare presents a hazard, especially for older drivers.

    To promote better policy, a DC Street Lighting Task Force now represents more than 100,000 residents by enrolling local groups including ANC 2D and Restore Mass Ave.  The Task Force has amassed technical data to show the streets would be just as safe for traffic and pedestrians with lights no more than 2700 Kelvin. 

      It appears the new Director of DDOT agrees. "I meet with the Street Light Task Force monthly," Director Marootian said at the March 19 meeting.

      Not clear is where 4000 and 5000 Kelvin blue-white lamps will be allowed in the District in future - or which of that kind already installed will stay.  The Street Light Task Force counted more than 4,000 LEDs of 4000 and 5000 Kelvin in 2017. (2) Fully 24% or 1,107 are in Ward 7.  But these very bright lights are not hard to miss in Ward 2, which includes downtown and Dupont Circle, and in the commercial corridors of Ward 3.

Correlated Color Temperature in Kelvins (US Department of Energy)

    At stake are the terms of a Request for Proposals (RFP) which DDOT is preparing with the Office of Public and Private Partnerships (OP3).  The RFP would enable private companies to bid for the job of modernizing all the city's street lights and related infrastructure. (3) The RFP is to be issued this spring but it must be reviewed by the City Council first. 

     Council Member Mary Cheh, as Chair of the Committee on Transportation and the Environment, held a roundtable on the issue in June 2017. At that time, the Director of DDOT appeared to agree that such bright lights would not be installed until a policy was agreed. (According to local reports, such lights have been installed anyway.)

     At the public ANC meeting, Marootian, who took office in January, did not say whether or which of the present 4000- 5000 Kelvin LEDs would be replaced. 

    He did say "my goal is no more than 3000 Kelvin along Massachusetts Avenue," where, starting west from Dupont Circle, his department plans to replace the lights as part of a big infrastructure project.     

    Restore Mass Ave, a member of the STLF,  has urged warm-white lights of 2700 along Massachusetts Avenue.   The residents of 2540 Mass, one of Mass Ave's most famous apartment houses, have petitioned Council Member Cheh and Ward 2 Council Member Jack Evans for lights no brighter than 2700 Kelvin.
RMA President Deborah Shapley and Jeff Marootian 
at a Dupont Circle meeting in December
(1) American Medical Association

 (2) What-is-the-Street-Light-Task-Force (June 2017).

(3) Smart Lighting Project page

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