Traffic Lights:

Meaning: These are signalling devices positioned at road intersections, pedestrian crossings and other locations to control conflicting flows of traffic.

• Green light: allows traffic to proceed in the direction denoted, if it is safe to do so
• Amber Light:   the yellow (or amber) light warns that the signal will be changing from green to red (and from red to green in certain countries.
• Red Lights:  the red signal prohibits any traffic from proceeding.  A flashing red indication is treated as a stop sign.

History

1. The first manually operated gas-lit traffic light was installed in 1868 in London.
2. Invented by : railway engineer JP Knight.
3. It featured moving arms, and gas-powered lamps in red and green for use at night time.
4. The project was short-lived after an explosion in 1869 when a leak in gas lines passing under the device exploded, and seriously injured the police officer operating the lights.

Electric Traffic Light System:

1. The first electric traffic light was developed in 1912
2. By: Lester Wire, a police officer in Salt Lake City, Utah
3. First Installed : In Cleveland, Ohio
4. Date : 5 August, 1914
5. Street: the American Traffic Signal Company installed a traffic signal system on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio.
6. It featured four pairs of red and green lights that served as stop-go indicators and each of them was mounted on a corner post.
7. worked via a manually operated switch inside a booth.

First three Colors light:

1. Year: In 1918
2. Place: New York

Traffic tree:

1. The most impressive traffic light specimen ever to be unleashed on the world’s streets was the Traffic Light Tree.
2. Created by French sculptor Pierre Vivant
3. year:  1998.
4. The imposing eight-metre tall tree consists of 75 sets of lights.
5. It has become a favourite spot for tourists in London.

Google Homepage: 

• Google remembers this historic day by a black and white doddle with the red-green lights of the traffic signal being the center of the attraction.
• Vintage cars, three at one end and three on the other, with alphabets G O O G L E on them move across the streets following the traffic signal rules.
• When you click on the doodle it directs you to the search page showing you the results to the query “when was the first traffic light installed” followed by various links giving the history and answers on the same.