Traffic Light

================

A traffic light, also known as a traffic signal or traffic signals, is a luminous signal used primarily in road traffic at intersections, pedestrian crossings, and other areas where conflicting traffic flows may occur.

Designation

Traffic lights are referred to differently in various countries. In Germany, Austria, and Switzerland, they are designated as part of the Road Traffic Code (StVO) as a light sign system (LZA). In Austria, it is also referred to as a transport facility in the Austrian Road Traffic Code (§ 41), while in Switzerland, it is mentioned in the Signalisation Ordinance (SSV).

Functionality

Traffic lights arrange a specific behavior for road users by providing controlled signals. These traffic signs, varying in shape and color, each have a distinct meaning and apply only to the respective direction of travel or pedestrian crossing being regulated.

Colors and Conventions

According to a universally recognized convention, the lights of a traffic light can have only three colors:

* Red: indicating a stop
* Green: indicating free passage
* Yellow-Orange: warning of an impending change from green to red

While this premise is valid for all countries, not all nations use the same conventions regarding the sequence of color appearance. For example, in Italy, yellow is used to preannounce the imminent order to stop, whereas in other states, it may be used in combination with red to indicate the approach of a free passage.

History

The first recorded example of a traffic light dates back to 1868, when a police officer in London used red and green gas lamps to regulate traffic at an intersection. However, the modern electric traffic light is credited to Garrett Morgan, who patented his design in 1922.