Traffic lights
Introduction
Traffic lights, also known as traffic control signs,[1] are signaling devices that are placed at road intersections and other places to regulate traffic, and therefore, pedestrian traffic. The first traffic light, designed by John Peake Knight, was installed in London in 1868.
The rise of traffic signs is linked to the rapid increase in automobile traffic, especially in the United States after Henry Ford introduced the Model T in 1908 and began mass production from 1913. For the first time, cars were cheap and reliable enough for commuting.[2].
Etymology
The word semaphore comes from the Greek σῆμα (sema), which means signal, and φόρος (foros), which means carrier, that is, a semaphore is what "carries the signals".[3].
In Spanish, centuries ago, signal towers were called semaphores, which extended throughout the territory, from which, by means of optical signals (lights at night, colored flags during the day), important news was communicated, faster than with a galloping horse. This was also the name given to the stations from which the optical telegraph signals established on the coasts and in ports were transmitted and whose objective was to announce the arrivals and maneuvers of ships coming from the high seas or sailing in sight or to give them urgent notices by means of balls or flags or to receive them from them. The semaphore consisted of a high mast on which the lookouts made signals using crossbars with the aforementioned balls or with flags and, if it was night, with flashlights. Typically, semaphores were in communication with nearby telegraph stations.[4].
Currently, a traffic light can be considered a mechanical or electrical device that regulates vehicle and pedestrian traffic at road intersections.
The dictionary of the Royal Spanish Academy defines the traffic light as:[3].
History
On December 10, 1868, the first traffic light was installed in London. It was designed by railway engineer John Peake Knight, who based it on railway signals of the time. The first traffic light was very different from the current one, with two arms that were raised to indicate the direction in which to stop. In addition, red and green gas lamps were used for night operation. However, this first traffic light was manual, requiring a police officer to control it at all times. This first traffic light exploded just one month later, on January 2, 1869, seriously injuring the police officer who was controlling it.[5][6].