Traffic Lights: Every day, billions of people around the world follow the same simple traffic rules. Stop at red light, move at green light and get ready at yellow light. These colors have become such a natural part of modern life that most people never stop to think why they were chosen. Let us know what is the answer to this question.

Color signals were first introduced

Modern traffic signaling can be traced back to British railway companies in the 1830s and 1840s. Early railways needed a reliable system to communicate with train drivers and prevent collisions on busy tracks. One of the key people involved in developing these signaling ideas was Henry Booth. He was an engineer associated with the Liverpool and Manchester Railway. At that time three colors were used for railway signaling. Red meant danger or stop, green meant caution, white meant safe or move ahead.

The early use of white as a proceed signal ultimately created a dangerous confusion for train drivers at night. Railway operators found that in the dark the white signal lights could easily be mistaken for stars or other distant lights. In a major incident, the red glass lens installed on a railway signal reportedly broke and fell, exposing the white lamp behind it. The train driver mistakenly thought the white light was a signal that the track was clear and it was safe to proceed. Due to this misunderstanding the trains collided. After this accident, the railway officials removed the white color and chose green. Also yellow color became the new caution signal.

World’s first traffic light

This system, which started with the train, became the foundation of traffic lights. The first road traffic signal in history was installed outside the Houses of Parliament in London on 10 December 1868. This system was designed by John Pick Knight. He adopted the concept of railway signaling for road traffic management. Initially its gas version was prepared and only red and green lamps were used. A police officer used to operate these signals by hand to control horse carriages and pedestrians.

electric traffic light

The next major breakthrough came in 1912 when Lester Wire built the first electric traffic light in the United States. Later in 1920, William Potts, another American police officer, officially introduced the modern three-color traffic light system by adding a yellow or amber signal between the red and green.

Why was red color chosen for stopping?

There was a scientific reason for choosing red color for stop signals. Red light has the longest wavelength in the visible color spectrum. It is approximately between 620 to 740 nanometers. Due to this longer wavelength, red light scatters less in dust, fog, smoke and rain. Psychologically too, humans naturally associate the color red with danger, caution and emergency.

Why does green mean moving forward?

Green was chosen because the human eye is very sensitive to green wavelengths. It is approximately between 500 to 565 nanometers. This sensitivity helps people quickly identify the green signal both during the day and at night.

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