Traffic lights were used before the advent of the motorcar. In 1868, British railroad signal engineer J P Knight invented the first traffic light, a lantern with red and green signals. It was installed at the intersection of George and Bridge Streets in front of the the British House of Commons to control the flow of horse buggies and pedestrians.

Motorcars were introduced to the US in the late 1890s and the need for traffic control soon became obvious. A number of people came up with ideas for traffic control. In 1910, Earnest Sirrine of Chicago, Illinois filed for a patent (no 976,939) for what is considered the first automatic street traffic system, using non illuminated words STOP and PROCEED.

In 1912, Lester Wire of Salt Lake City, Utah invented an electric traffic light that used red and green lights. However, he did not apply for a patent. The next year, James Hoge received patent no 1,251,666 for a manually controlled traffic light system using electric lights. It was installed in Cleveland, Ohio in 1914, displaying the words STOP and MOVE.

The first traffic light system to use red and green lights were patented by William Ghiglieri of San Francisco, California in 1917 (patented no 1,224,632). His design could be operated manually or in automatic...

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http://hokyky..com/2016/08/did-you-know-traffic-light-has-been-in_12.html

and who says traffic is associated with vehicles alone?

Impressive