What is the history of traffic lights ?

What is the history of traffic lights ?

We can always find  traffic lights on each intersection .
Red meant “stop” and green meant “caution.”
But do you know the orgin of  traffic lights ?

1.The orgin of color scheme for traffic lights.

While some of the specifics have been lost to history, it is known that this color scheme derives from a system used by the railroad industry since the 1830s. At this time, railroad companies developed a lighted means to let train engineers know when to stop or go, with different lighted colors representing different actions. They chose red as the color for stop, it is thought, because red has for centuries been used to indicate danger. For the other colors, they chose white as the color for go and green as the color for caution.

2.Why use yellow color scheme for  traffic lights ?

The choice of a white light for go turned out to cause a lot of problems. For instance, in an incident in 1914 a red lens fell out of its holder leaving the white light behind it exposed. This ended with a train running a “stop” signal and crashing into another train. Thus, the railroad decided to change it so the green light meant go and a caution “yellow” was chosen, primarily because the color is so distinct from the other two colors used.

3.Traffic signals‘ birth in London

The world’s first traffic light came into being before the automobile was in use, and traffic consisted only of pedestrians, buggies, and wagons. Installed at an intersection in London in 1868, it was a revolving lantern with red and green signals. Red meant “stop” and green meant “caution.” The lantern, illuminated by gas, was turned by means of a lever at its base so that the appropriate light faced traffic. On January 2, 1869, this crude traffic light exploded, injuring the policeman who was operating it.

However, this method turned out to be unsafe. In 1869, a traffic signal exploded following a leak in one of the gas lines below, severely injuring the policeman operating it. This led to the semaphore project being dropped in London.

America’s evolves the signal system

In America, the semaphore system continued to be rolled out, with more and more motorists, carts and trucks travelling on the road. However, with more traffic officers found it was difficult to judge congestion.

Potsdamer Platz in Berlin, Germany, in 1925 with the  traffic light tower in the centre.Hulton Archive
While some cities began installing traffic towers, allowing officers to have a higher view of the traffic, in Utah in 1912, policeman Lester Wire developed the first electric traffic light system with red and green lights.

Two years later, the first electric signal was installed in Cleveland. It was based on a design by James Hoge and allowed police and fire crew to control the signals in case of emergencies.