Willis Lamm's
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"GOING DARK!" Eaglelux 2-Color Fixed 4-Way Traffic Signal Type 42E |
The first electric two-color traffic signal was designed and installed in 1912 by Salt Lake City police officer Lester Wire to assist traffic officers at intersections. (The first three-color signal was designed by Detroit Traffic Police Superintendent William Potts in 1920.) These early signals were manually controlled. Eventually both the two color and three color signals became "automatic" or electrically controlled. |
Green indication.
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Dark interval during change.
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Red indication.
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Eagle Signal soon factory configured their standard two color signal controllers with the four circuit "red overlapping green" change sequence. In reality this two color overlap display was safer than having the signal going dark, particularly in early days when signals were often painted black or dark green. Although the law required drivers to stop at any unlit traffic signals, motorists unfamiliar with an area and not knowing which intersections had signals might not notice a dark colored unlit signal. While a few two-color signals displaying the red-green overlap were in service as late as 2003, the "dark out" displays were generally eliminated by the 1970s. |
A two-color signal in Daytona Beach, FL. |