Traffic Light R/G (X and Arrow)

Traffic Light

Voltage input: 12/24/220V

Size: 200mm

Traffic Light

Traffic lights, traffic signals, or stoplights – also known as robots in South Africa^[1][2] and Namibia – are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control the flow of traffic.^[3]

Traffic lights consist normally of three signals, transmitting meaningful information to road users through colours and symbols including arrows and bicycles. The regular traffic light colours are red, yellow (also known as amber), and green arranged vertically or horizontally in that order. Although this is internationally standardised,^[4] variations exist on national and local scales as to traffic light sequences and laws.^[5]

The method was first introduced in December 1868 on Parliament Square in London to reduce the need for police officers to control traffic.^[6] Since then, electricity and computerised control has advanced traffic light technology and increased intersection capacity.^[7] The system is also used for other purposes, for example, to control pedestrian movements, variable lane control (such as tidal flow systems or smart motorways), and railway level crossings.

The first system of traffic signals was installed as a way to replace police officer control of vehicular traffic outside the Houses of Parliament in London on 9 December 1868.^[8] In the first two decades of the 20th century, semaphore traffic signals like the one in London were in use all over the United States with each state having its own design of the device. In many cases, it was controlled by a traffic officer who would blow a whistle before changing the commands on this signal to help alert travellers of the change.^[9]

Traffic Light

In 1912, the first electric traffic light was developed by Lester Wire, a policeman in Salt Lake City, Utah.^[10] It was installed by the American Traffic Signal Company on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio.^[11][12][13] The first four-way, three-colour traffic light was created by William Potts in Detroit, Michigan in 1920.^[14] His design was the first to include an amber ‘caution’ light along with red and green lights.^[15] Potts was Superintendent of Signals for the Police Department of Detroit. He installed automatic four-way, three-colour traffic lights in 15 towers across Detroit in 1921.^[16][15][14] By 1922 traffic towers were beginning to be controlled by automatic timers more widely. The main advantage of the use of the timer was that it saved cities money by replacing traffic officers. The city of New York was able to reassign all but 500 of its 6,000 officers working on the traffic squad; this saved the city $12,500,000.^[17]

Garrett Morgan received a patent for the design of manually-operated three-way traffic light with moving arms in 1923.^[18]

The control of traffic lights made a big turn with the rise of computers in America in the 1950s. One of the best historical examples of computerized control of lights was in Denver in 1952. In 1967, the city of Toronto was the first to use more advanced computers that were better at vehicle detection.^[7] The computers maintained control over 159 signals in the cities through telephone lines.^[19]