Colour is a silent language that affects our behavioural response in our day to day lives. The behavioural response happens naturally without us being aware of it. For example, the colour red can heighten our perception of danger just by seeing it. With regards to the traffic light, we all know that - a red light means “STOP”, a yellow light means “ SLOW DOWN” and green light means “GO”. But it is very interesting to know, why the traffic lights are red, yellow and green?
How It All Started:- The colours used by automobile traffic light system was originally adopted from the colour code system used by railroad engineers. The colour code was used by them as a traffic signal to control the trains on the railroad and to prevent fatal train collisions by providing trains with advance warning of danger.
The first colour that was selected by the rail road engineers to represent a stop signal was the colour red. This colour - the colour of blood - was selected because it symbolizes danger or warning. Thus, it was logically the most likely choice to get the attention of anyone.
For the other two colours, railroad engineers experimented with the colours green which was the colour for “caution” and white (clear) which was the colour for “go”. However, in the 1830s, these traffic signals lights were colored by using red, green and clear filters. But due to the use of these filters some very serious train collisions occurred as the street lights, distant stars, glare of the sunlight and other lights were easily mistaken for the “go” light. In addition to this, sometimes the red filter of a “stop” traffic signal fell out leaving the bulb emitting white light which in a sense would be signaling the message “go”. To correct this problem engineers made modifications where red light would be the signal “stop”, yellow light “caution” and green “go”.
Traffic system became worse with the coming of automobiles. Due to the fact that the railroad traffic colour system worked so well with the railroad system, it was readily adopted for automobile traffic light system. This adoption came through a police officer, William Potts of Detroit, of Michigan, USA. He used the same scheme of colours of the railroad traffic and built the world’s first 4-way three colour traffic light. This was installed in Detroit, USA in 1920.
During this time, African American Garrett Augustus Morgan (1877-1963), invented the electric automatic traffic light. This was installed in Cleveland, Ohio, USA in 1914 and had only two lights: red and green. However, the yellow light was added after the need for a “caution” light became crucial for the traffic signal to serve its purpose effectively. This is how the modern four-way traffic lights came.