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Speaker 1: Welcome to brain Stuff from how Stuff works dot com

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Speaker 1: where smart Happens. Hi, I'm Marshall Brain with today's question,

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Speaker 1: why are they replacing all of the traffic lights with

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Speaker 1: L E D s? Most cities in the United States

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Speaker 1: are in the process of replacing their incandescent traffic lights

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Speaker 1: with L e ED units because of three big advantages. First,

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Speaker 1: L e D s are brighter. The L e ED

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Speaker 1: arrays fill the entire hole and have an equal brightness

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Speaker 1: across the entire surface, making them brighter overall. Second, LED

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Speaker 1: bulbs last for years, while halogen bulbs last for months.

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Speaker 1: Increasing the replacement interval can save big dollars for any city.

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Speaker 1: And Third, LED bulbs save a lot of energy. The

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Speaker 1: energy savings can be gigantic. Assume that a traffic light

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Speaker 1: uses one hundred watt bulbs today, the light is on

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Speaker 1: twenty four hours a day, so it uses two and

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Speaker 1: a half kilowatt hours of electricity. It means that one

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Speaker 1: traffic signal costs about twenty cents a day to operate,

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Speaker 1: or about seventy three dollars a year. There are perhaps

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Speaker 1: eight signals per intersections, so that's almost six hundred dollars

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Speaker 1: per year. In power per intersection, and a big city

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Speaker 1: has thousands of intersections, so it can cost millions of

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Speaker 1: dollars just to power all the traffic lights. Led bulbs

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Speaker 1: can easily save a million dollars a year or more.

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Speaker 1: These low energy bulbs also open up the possibility of

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Speaker 1: using solar panels instead of running an electrical line, which

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Speaker 1: saves money in remote areas. Be sure to check out

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Speaker 1: our new video podcast, Stuff from the Future. Join how

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Speaker 1: Stuff Work staff as we explore the most promising and

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Speaker 1: perplexing possibilities of tomorrow the house Stuff Works. I Find

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