Why are traffic lights green yellow and red instead of blue yellow and red (primary colors)?
2007-02-24 09:28:12 · 4 answers · asked by Anonymous in Cars & Transportation ➔ Other - Cars & Transportation
The present system of color coding was developed by the railroads around the time of World War I. But its roots go back much further. Tradition among railroaders has it that red was chosen for "stop" in commemoration of a farmer who tried to flag down an early choo-choo with his red shirt. This is cute, but BS. Red, the color of blood, has been a danger signal since time immemorial. It's said the Roman legions bore the red banner of the war god Mars into battle 2,000 years ago.
The other colors have changed over time. When the first primitive railroad signaling devices were developed in the 1830s and 1840s, red meant "stop," green meant "caution," and clear (i.e., white) meant "go." This system had several defects. One obvious problem was the fact that the white signal could easily be confused with an ordinary white light. What was worse, however, was the fact that the system wasn't fail-safe. This was tragically demonstrated sometime around 1914. The red lens supposedly fell out of a signal so that it erroneously showed a white indication. This caused a train to sail through the "stop" signal, resulting in a disastrous crash. The railroads subsequently decided to drop white and make green "go" and yellow "caution." Yellow presumably was chosen because it was readily visible and offered the most striking contrast to the other two colors. When the first electric traffic signals were installed in Cleveland, Ohio, in 1914, they used red and green indications. When the first modern automatic traffic signals were put up in Detroit in the early 1920s, they used red, yellow, and green, and that's what we're stuck with today.
2007-02-24 09:32:56 · answer #1 · answered by They call me ... Trixie. 7 · 0⤊ 0⤋
The colors originate from nautical right-of-way lights. The red usually has some orange in its hue, and green usually has some blue in it for people with red-green color blindness. This all comes from Wikipedia.
2007-02-24 17:39:55 · answer #2 · answered by Aaron R 1 · 0⤊ 0⤋
Blue doesnt stand out as much as green... so blue would be ineffective
2007-02-24 17:32:42 · answer #3 · answered by Anonymous · 0⤊ 0⤋
well because green they always thought of as go
2007-02-24 17:36:42 · answer #4 · answered by Anonymous · 0⤊ 0⤋