Greater City Providence

LED Street Lighting

a single LED

Schematic by Greater City Providence’s resident EE Matthew Coolidge

According to a post on website, New York City is going to be testing out new LED street lamps.

New York City’s Department of Transportation has tapped the Office for Visual Interaction for testing LED street lighting around the Big Apple. If successful, all of the city’s 300,000 street lamps could one day be made up of LEDs.

This is a very cool idea, and in my opinion, an inevitable evolution. Since LEDs use less power than existing halogen, incandescent, or even fluorescent bulbs, it makes sense that this will be the choice in illuminating miles and miles of roadway. Moreover, when cities and states start ordering LED based street-lights, the quantity needed will no doubt force down the cost, eventually leading the way to more adoption of LEDs as a lighting source.

Taking this idea a step further, since LEDs require so little power, perhaps it’s not unreasonable to think of a street-lamp that charges itself with a solar cell? Unlike some other types of lamps that use a gas to illuminate, LEDs can turn on and off instantaneously. One could even imagine street-lamps smart enough to turn on or off automatically to scare the crap out of you save energy if there is no one in proximity.

Another website, states:

If all of the world’s light bulbs were replaced with LEDs for a period of 10 years, Schubert and Kim estimate the following benefits would be realized:

  • Energy savings of 1.9 – 1020 joules
  • Electrical energy consumption would be reduced by terawatt hours
  • Financial savings of $1.83 trillion
  • Carbon dioxide emissions would be reduced by 10.68 gigatons
  • Crude oil consumption would be reduced by 962 million barrels
  • The number of required global power plants would be reduced by 280

We’ve already seen how LEDs have been used to improve traffic signals. LEDs use less energy, and thus will cost less to operate in the long run. Some types of LEDs even have amazingly long lifespans, but it will take some early adopters, like (hopefully) NYC, to make this green-dream come true.

Matthew Coolidge

Matthew Coolidge is co-founder of Greater City Providence. In addition to the occasional blog post about cycling, sailing, or urban rant, he works as an Electrical Engineer, often traveling to major cities and ports around the globe, or simply Warwick.


  • Metropolis Magazine has a good article about LED street lighting in this month’s issue. One of the benefits they discuss is the quality of the light. The white of LEDs is more like day light and does not give off the yellow/orange glow that sodium vapor lights do.

    The white light of LEDs might even make people feel safer:

    In Anchorage, where local officials are switching an ambitious 16,500 streetlights to LEDs, a group of residents was asked to compare the fixtures’ soft-white color temperature – similar to full moonlight – to the treacly glare of high-pressure sodium. Respondents overwhelmingly declared the white light brighter, more attractive, and safer-seeming, says Michael Barber, the city’s lighting-program manager and resource-efficiency specialist, even though the old lamps emitted twice as many lumens. There’s a ­science behind this. According to John Bullough, senior research scientist at Rensselaer Polytechnic Institute, certain photoreceptors in human eyes are more active after dark and allow us to see better in white light.

    In New York they are replacing their cobraheads with LEDs, here’s a photo of the new deisgn:

    Photo from Office for Visual Interaction via Metropolis

    Ann Arbor, Michigan seems to be way ahead of other city’s in the implementation of LED lights. Here is an olde tyme style lamp from Ann Arbor that would feel right at home in Providence:

    Photo from City of Ann Arbor via Metropolis

  • The New York Times had several articles about LEDs ranging from lightbulbs, to factories, to Dean Kamen’s house and of course street lights in NYC.
    Search for articles:


  • Great link Matt. This seems like an absolute no-brainer in every respect. Is there any downside here at all? From a cost perspective, I imagine the savings will eventually have the bulbs pay for themselves…

  • I got LED christmas lights this year. I’ll let you all know how they work out.

  • Update. we put the lights on the tree tonight. Two strands. One half of one strand is already not working. Switched out the bulb closest to the outage. No change. So far, I’m not loving the LEDs.

  • Schematic above is not a good idea. When connecting multiple LEDs to the same power source you should either connect them in series or give each its own current-limiting resistor. Multiple LEDs in parallel with a single current-limiting resistor are not guaranteed to evenly share current. Manufacturing tolerances or temperature differences can cause one to draw more than its share of the current, overheat and fail. That can then either short the whole thing out, or fail open, at which point the others will draw too much current and then also die. This is why traffic lamps and streetlights use strings of LEDs in series with a single current-regulating circuit for each string, rather than just wiring a lot of LEDs in parallel.

  • Oh, touche, ellindsey. You make an excellent point.

    Jen, I withdraw my previous comment. Perhaps the problem with your tree lights is that they DO match my schematic!

    Ellindsey, I appreciate your attention to detail, and I have updated my schematic above.
    Thanks for keeping me honest! -Matthew

  • LED might be using less electricity than the average house lighting, but the 100 lm/watt of (white) office TL5 tubes or the 200lm/watt of (yellow) Natrium street light tubes are very hard to beat. And if they are going to use LED’s for street lights, please use the red glow at startup.

    The best energy-saver: turn of street lights after the evening rush hours. Just light the highway exits and major crossings.

  • The best energy-saver: turn of street lights after the evening rush hours. Just light the highway exits and major crossings.

    Because there’s no one ever out after the sun goes down strolling along on the sidewalks of a city or town.

    Certainly not on a warm summer night, maybe going to get a slice of pizza or ice cream, maybe going to meet friends for a drink.

    Yes. After dark, there are never any pedestrians in a city.

  • The electricity use savings over sodium vapor lights may be negligible, but I think in a city like Providence, we’d be looking to convert our decorative lighting like Ann Arbor has, which do not use sodium vapor bulbs. Also, another cost savings in addition to energy is labor. Sodium vapor lamps have an expected lifespan of 3-5 years, whereas the LED lights have an expected life of 2 decades (according to the Metropolis article). Judging by the number of decorative lights I see out around Providence, the lifespan of whatever bulbs are in those aren’t too much better. While the upfront cost of LED lights is currently higher than traditional options, city’s such as Raleigh, Anchorage, and Ann Arbor expect to recoup those costs over time through labor savings.

    Also the ability to to direct the light better is an attractive feature of LEDs. In areas like Benefit Street, where the Historic society is adamant about having decorative lighting we often sacrifice safety for this type of lighting. If we can have decorative lights that focus brighter light where needed (i.e. on the street and not up in the sky or into people’s yards) then we get the best of both aesthetics and safety.

    As we prepare to rebuild the streetgrid in the land soon to be vacated by Route 195, now would be a good time for Providence to prepare a pilot program for decorative LED streetlights in that area. If they work well in the 195 land, we can start to roll them out through the rest of the city.

  • Just too bad the normal orange low-pressure-sodium street lights are much more efficient then white LEDs. Actually those orange street lights can be over 100% MORE efficient then high powered LED lights that would be needed for street light duty.

    White LEDs also have a short life time, and the more powerful they are, the shorter the the life span. White LEDs are really blue LEDs with a phosphor coating, the coating wears down and eventually blocks out all light.

    The only advantage that white LEDs have over low-pressure-sodium is that they emit white light instead of orange, much more pleasing, but in terms of efficiency, it is a HUGE step backwards.

  • Just to add, the life span of White LEDs is so low, you would most likely be replacing them just as often as sodium vapor bulbs.

  • While many people seem to be so concerned about astetics, keeping old style lights, rather than using cost saving Led’s. Yet, they also, CRY when the City, State and, Government has to raise their taxes to pay for all the FREE lighting they receive and keeps them safe. Has anyone ever seen the reality of how much brighter and safer these lights really are. Not, to mention the fact that they use 90% LESS electricity than conventional bulbs and Embarassingly outlast old fashioned bulbs. I would be HIGHLY in favor of Raised taxes IF LED’s were not used. GO GREEN and STOP crying

  • Also, to consider, if ALL cities and Towns Switched, Imagine the less oil demand which would be required to be imported. Then we could ALL save on the prices of Oil and GAsoline alone. Just think about it!

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  • Hi all, great topic! Seamus here from WHITElight in Ireland we specialize in LED street lighting and have carried out many projects here in Europe. LED lighting is not all it seems, we have had major problems in the past with drivers and heat which is a big problem for LED lighting also if the LED is on more than 8 hours it starts to deteriorate. The high power C**E LED which you are using are giving about 28lm per watt after a 100 hour burn this is useless for street lighting and you will be replacing most of them in the next 2 years due to issues with heat and browning I know because we were there 2 years ago. The best combination of equipment is medium power LED (RGB) with current limiting driver in a well ventilated fixture but at the moment the lm output is not sufficient for street lighting. We are using blue LED coated with phosphate which works well but will it last 50,000 hours we do not think so we would now predict 30,000 hours but improving all the time.

  • led street light can now be powered from dc or ac voltage due to the newer drivers for the led that have come out. this lets led street lights be powered from solar panels or a small wind turbine on the pole.there are videos on you tube showing this.led can be dimmed or turned on/off without shorting there life.there are now lighting system that are connecting street lights as network devices on power company grids allowing them to be dimmed/turned on or off remotely.cree one vendor of led chips will be having led with higher lm there test led hit 161 lm in testing. I donated two beta led street lights to north attleboro electric for testing.

  • On a related note, I just spotted this article on LEDs getting even more efficient:

    From the article:
    “The new polarization-matched LED, developed in collaboration with Samsung Electro-Mechanics, exhibits an 18 percent increase in light output and a 22 percent increase in wall-plug efficiency, which essentially measures the amount of electricity the LED converts into light.”

  • With all these comparisons of LED to other technologies, there is no mention of magnetic induction light technology. This technology has been around for 100 years and has just recently been updated and costs brought way down.
    Magnetic Induction Lights have a lifespan of 100,000 hours and are as efficient or more efficient than LED, have a higher Lumen per watt (80+ for induction vs. 40-60 for LED), and costs are much less. The LED technology is, on average, 3-5 times more expensive.
    Also, the Induction light technology is the greenest of all products on the market. It does have a small about of amalgam, however, it is 99% recyclable.
    LED is a new buzz-word in the world of street lighting, however, it is a technology that has its issues. LED has a solid-state circuit board, like the one in your computer. Your computer has a fan in it to keep it cool. LED’s have a heat sink in it, however, there is no or little air circulation to keep it cool.
    Cities like New York get very hot in the summer. This combined with the internal heat of the circuit, is not good.
    Induction lamps can be used for very low temperature (around 20 degrees below 0F and high temps of over 200 degrees F).
    Also, the Amko SOLARA induction light has had ongoing testing for over 13 years, but has been on the market 3 years. The testing includes aging controls, high temperature lamp aging over, etc. to artificially induce the life of the light to make sure it can last atleast 70% of life at 60,000 hours.
    The Amko SOLARA induction light is dimmable and has been designed to be used with the Amko Eclipse controls to further increase energy savings.
    See or email with any more questions or comments. (

  • cleanlight greenlight has just sold their first city streetlights with way more to come. Look at this product and you’ll never look back to old stodgy lighting. Tremendous ROI and excellent color.

  • Just because LEDS are the latest dosent mean they are the greatest. Power plants dont produce more power like the gas peddle does for your car. The power produced during the day and night are about the same, only much more is needed at peak hours then late night hours (when street lights are on) So although it dosent use as much power, that power is still being produced anyway, so no savings is really happening when you think about it

  • If a utility sees overall less demand they will eventually compensate by reducing production. For the city there would be a tangible cost savings. The installation of LED streetlights more importantly sends a strong message and gives a visual suggestion to the public that we all need to reduce our energy consumption. LEDs use less energy that compact fluorescents. If every building in the city only replaced only their exterior lighting with LEDs the energy and cost savings would be huge.

  • Mark:
    I let your first advertisement go through. I’m not allowing a second.

  • As in hybrid lights using wind and solar, we keep input interface as 24VDC,36VDC,48VDC etc, GreenZM’s strength is its structure, light distribution photometric technology and PSU technology, (Lighting power will be half after 6 hours, say, if lighted on 18:00PM, power is half after 24:00PM as few traffic at nights), with 2 parts as PSU (Power Supplier Unit) + Lighting Boards, (PSU Input is 85VAC ~ 265VAC, Output is 48VDC, which is the hybrid interface for wind/solar power). You guys can connect solar panel in series to create 48VDC.

Providence, RI
5:12 am8:24 pm EDT
Feels like: 72°F
Wind: 7mph WNW
Humidity: 65%
Pressure: 29.8"Hg
UV index: 1
90°F / 68°F
86°F / 59°F
79°F / 61°F