06 January 2014

Motion-activated street lights

These are being marketed primarily as energy- and cost-saving devices -
...the Dutch entrepreneur found some statistical data showing that just keeping the city lights on costs Europe, alone, over 10 billion Euros each year and is responsible for more than 40 percent of a government’s energy usage... 
- but I'll applaud them primarily for the minimizing of light pollution.
...he retrofits existing street lamps with a specialized interlinked network of sensors that automatically dials down the brightness when no one is around and restores maximum radiance upon detecting the presence of oncoming human activity, such as moving cars, pedestrians and bicycles... Though he wouldn’t disclose how much installation would cost, Shah assures that it would take municipalities about three to four years to make up for the initial investment in annual cost savings. 
The rest of the story is at Smithsonian.


  1. Hmm.. OK I'm curious, and this is an idle question..

    How much power do the sensor take? And how long do they last? (compared to just leaving the light on.)

    To run this, you need to power a sensor of some type -- probably a motion detector? So even if the light is off (how much power does the light use?) the sensor will need to powered (how much power does the sensor use?). And of course, the sensor and switch are an extra set of equipment to fail. Replacing things that fail will cost time and money -- and does cycling the light on and off reduce the lifetime of the light?

    I'm just curious -- I assume this does save energy and money. But I don't think I've ever seen anyone calculate this out.

  2. What about if you are traveling at a high speed and there's a moose standing on the pavement? How much visual notice will you get that you need to make a correction to avoid hitting said moose?

  3. A couple of things.... First, I like the idea. I would (to avoid the whole moose-in-the-road scenario) design the lights to come on farther ahead. Second, consider how many roads have only a SINGLE car driving down them. That means if two or three (or 20) cars are on such a road, you have no savings--or much less.

    I also wondered if crime might be an issue. But if someone is standing in the shadows...it would seem the light would come on tracking THEM.

    Here's another issue. You are wondering whether to turn down a darkened street. You do. You go 1/4 of a mile...only to find that in the darkness is the burned out shell of a car in the middle of the road. You must now backtrack. Unless, that is, the zombies in the shadows, sensing a chance for you, now rush out as you are turning around.

  4. We have a problem with streetlights that just go off, usually just as I approach them. When I'm out walking dogs at night, I'm pretty safe, but it really bothers me that they seem to know when I approach, and only then do they turn off. This goes on for many blocks. I'm really not paranoid, it just the timing seems odd.

  5. Led lights are on dim mode then become bright when passing .

  6. Reminds me of "Alien Earth" By Robin Hobb. How Tug, the alien embedded into the ship, turns on the lights for Connie and John when they wake up from their interstellar sleep.

    The day the AIs of the world turn against us they will stop turning on the lights and play tricks on us...


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