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A volume detector of a traffic light system at a neighborhood junction in Haifa
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This is the infrared volume detector that control the smart traffic lights systems (Green light on demand) in Israel. In this case it is mounted on its own post. Several pedestrian crossings in this juction have a crossing button that you must hit it in order for the pedestrian light to be green or it will never become green.
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In the 1950s Baltimore city (I donno about the other areas of Maryland in my area) but Baltimore City used Sonic sensor which goes over the road (like a streetlight but mounted lower) and when a car passes, it detects something related to sounds (like a bat would send sound and it bounces back if you know what I mean) and it would tell the light to turn green.
By the way i think that our LED traffic lights are actually build similar to the ones outside Israel, Ie.. with direct LED arrays and lens and without any reflectors, but the lens and the LEDs arrays is build in such a way that you can't see the LEDs and the entrie traffic light looks outside exactly like the incandescent ones but with brighter and saturated color and also they have a much narrower bands in their spectra.