When, and by whom, was it originally decided that green would signify "go", and red would signify "stop" in traffic lights?

trevorofbude

I have found a link which gives a reasonable explanation see :- http://www.straightdope.com/columns/read/437/who-decided-red-means-stop-and-green-means-go 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. Dec 02 11, 5:33 AM

coachpauly

On December 10, 1868, the first traffic lights were installed outside the British Houses of Parliament in London, by the railway engineer J. P. Knight. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic. Unfortunately, it exploded on 2 January 1869, injuring or killing the policeman who was operating it. Herbet Thorp wired the first permanent traffic lights in England. They are in Leeds. The modern electric traffic light is an American invention. As early as 1912 in Salt Lake City, Utah, policeman Lester Wire invented the first red-green electric traffic lights. On August 5, 1914, the American Traffic Signal Company installed a traffic signal system on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio. It had two colors, red and green, and a buzzer, based on the design of James Hoge, to provide a warning for color changes. http://en.wikipedia.org/wiki/Traffic_light Dec 02 11, 11:15 PM

sportsherald

This brings to mind the story I heard decades ago in school, and apparently confirmed in Wikipedia, that during the "Cultural Revolution" in Maoist China, there were attempts to switch the rules to red (Communism) meaning "go," and similarly, to switch to driving on the left, for ideological reasons. The same entry explains some cultural background to the apparently chaotic driving practices seen in modern China. http://en.wikipedia.org/wiki/Rules_of_the_road_in_the_People's_Republic_of_China Dec 03 11, 5:46 PM