Editing Traffic light (section)

== History ==
{{Main|History of traffic lights}}
In December 1868, the first system of traffic signals, which was a semaphore traffic signal, was installed as a way to replace police officer control of vehicular traffic outside the [[Palace of Westminster|Houses of Parliament]] in [[London]]. This system exploded on 2 January 1869 and was taken down. This early traffic signal led to other parts of the world implementing similar traffic signal systems. 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]]. These traffic signals were controlled by a [[traffic officer]] who changed the commands on the signal to direct traffic.{{sfnp|Sessions|1971|p=22}}

In 1912, the first electric traffic light was developed by [[Lester Wire]], a policeman in [[Salt Lake City]], [[Utah]].<ref>{{cite web |last=Bellis |first=Mary |date=5 February 1952 |title=The History of Roads and Asphalt |url=http://theinventors.org/library/inventors/blasphalt.htm |website=theinventors.org }}</ref> In August 1914, it was installed by the American Traffic Signal Company on the corner of East 105th Street and [[Euclid Avenue (Cleveland, Ohio)|Euclid Avenue]] in [[Cleveland]], Ohio.{{sfnp|Sessions|1971|pp=27–28}}<ref>{{cite journal |date=August 1914 |title=New Traffic Signal Installed |journal=The Motorist |publisher=Ken Pub. Co |pages=28–29}}</ref><ref>{{Cite web |title=Traffic signals: A brief history |website=Washington State Magazine |publisher=Washington State University |first1=Larry |last1=Clark |date=Fall 2019 |url=https://magazine.wsu.edu/web-extra/traffic-signals-a-brief-history/ |access-date=19 December 2021 |language=en-US}}</ref> In 1920, the first four-way, three-colour traffic light was created by [[William Potts (inventor)|William Potts]] in [[Detroit, Michigan]].<ref name=":11" /> His design was the first to include an amber 'caution' light along with red and green lights.<ref name=":12" /> Potts was Superintendent of Signals for the Police Department of Detroit. In 1921, he installed automatic four-way, three-colour traffic lights in 15 towers across Detroit.<ref name="Pollard082">{{cite journal |last=Pollard |first=Justin |date=September 2008 |doi-access=free |url=https://digital-library.theiet.org/content/journals/10.1049/et_20081518 |via=IET Digital Library |title=The Eccentric Engineer: The History of Traffic Lights Is Full of Twists and Turns |journal=Engineering and Technology |volume=3 |issue=15 |page=93 |doi=10.1049/et:20081518 |doi-broken-date=7 December 2024 }}</ref><ref name=":12">{{cite web |url=https://www.thehenryford.org/collections-and-research/digital-collections/artifact/227457/#slide=gs-225140 |title=First Tri-Color, Four-Directional Traffic Signal, 1920 |website=The Henry Ford |url-status=live |archive-url=https://web.archive.org/web/20240312133450/https://www.thehenryford.org/collections-and-research/digital-collections/artifact/227457/#slide=gs-225140 |archive-date= Mar 12, 2024 }}</ref><ref name=":11">{{cite web |url=http://large.stanford.edu/courses/2011/ph240/miller1/docs/moyer/ |title=Mr. 'Trafficlight' |date=March 1947 |first1=Sheldon |last1=Moyer |work=Motor News |via=large.stanford.edu |url-status=live |archive-url=https://web.archive.org/web/20230913014058/http://large.stanford.edu/courses/2011/ph240/miller1/docs/moyer/ |archive-date= Sep 13, 2023 }}</ref> 

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. [[New York City]] was able to reassign all but 500 of its 6,000 officers working on the traffic squad, saving the city $12,500,000.{{sfnp|McShane|1999|p=385}}

In 1923, [[Garrett Morgan]] patented a design of a manually operated three-way traffic light with moving arms.<ref>{{cite web |url=https://patents.google.com/patent/US1475024A/en |title=US Patent: US1475024A 'Traffic signal' (1923) |website=patents.google}}</ref>

The control of traffic lights changed 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, [[Toronto]] was the first to use more advanced computers that were better at vehicle detection.{{sfnp|Sessions|1971|p=141}} The computers maintained control over 159 signals in Toronto through telephone lines.{{sfnp|Sessions|1971|p=143}}