Signaling device to control competing flows of traffic

Traffic light

Traffic light

Traffic lights, traffic signals, or stoplights – known also as robots in South Africa<a href="#cite_note-1" style="counter-reset: mw-Ref 1;">[1]</a><a href="#cite_note-2" style="counter-reset: mw-Ref 2;">[2]</a> – are signalling devices positioned at <a href="/en/Intersection_(road)" title="Intersection (road)" class="wl">road intersections</a>, <a href="/en/Pedestrian_crossing" title="Pedestrian crossing" class="wl">pedestrian crossings</a>, and other locations in order to control flows of traffic.<a href="#cite_note-3" style="counter-reset: mw-Ref 3;">[3]</a>

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Signaling device to control competing flows of traffic</div>
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<figure class="mw-default-size wiki-thumb"><a href="/en/File:Modern_British_LED_Traffic_Light.jpg" class="mw-file-description image media-thumb" data-hash="File:Modern_British_LED_Traffic_Light.jpg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/91/Modern_British_LED_Traffic_Light.jpg/220px-Modern_British_LED_Traffic_Light.jpg" decoding="async" data-file-width="2112" data-file-height="2816" data-file-type="bitmap" height="293" width="220" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/91/Modern_British_LED_Traffic_Light.jpg/330px-Modern_British_LED_Traffic_Light.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/91/Modern_British_LED_Traffic_Light.jpg/440px-Modern_British_LED_Traffic_Light.jpg 2x" alt="Modern_British_LED_Traffic_Light.jpg"></a><figcaption>An LED 50 <a href="/en/Watt" title="Watt" class="wl">watt</a> traffic light in <a href="/en/Portsmouth" title="Portsmouth" class="wl">Portsmouth</a>, UK</figcaption></figure>
<figure class="mw-default-size wiki-thumb"><a href="/en/File:SCBD_Jakarta.jpg" class="mw-file-description image media-thumb" data-hash="File:SCBD_Jakarta.jpg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/SCBD_Jakarta.jpg/220px-SCBD_Jakarta.jpg" decoding="async" data-file-width="4160" data-file-height="3120" data-file-type="bitmap" height="165" width="220" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/SCBD_Jakarta.jpg/330px-SCBD_Jakarta.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b1/SCBD_Jakarta.jpg/440px-SCBD_Jakarta.jpg 2x" alt="SCBD_Jakarta.jpg"></a><figcaption>A traffic light in <a href="/en/Jakarta" title="Jakarta" class="wl">Jakarta</a>, <a href="/en/Indonesia" title="Indonesia" class="wl">Indonesia</a> with its count-down timer. A <a href="/en/Pedestrian_crossing" title="Pedestrian crossing" class="wl">pedestrian crossing</a> is also shown.</figcaption></figure>
Traffic lights consist normally of three signals, transmitting meaningful information to drivers and riders 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,<a href="#cite_note-:5-4" style="counter-reset: mw-Ref 4;">[4]</a> variations exist on national and local scales as to traffic light sequences and laws.<a href="#cite_note-5" style="counter-reset: mw-Ref 5;">[5]</a>

The method was first introduced in December 1868 on <a href="/en/Parliament_Square" title="Parliament Square" class="wl">Parliament Square</a> in <a href="/en/London" title="London" class="wl">London</a> to reduce the need for police officers to control traffic.<a href="#cite_note-:7-6" style="counter-reset: mw-Ref 6;">[6]</a> Since then, electricity and computerised control has advanced traffic light technology and increased intersection capacity.<a href="#cite_note-FOOTNOTESessions1971141-7" style="counter-reset: mw-Ref 7;">[7]</a> The system is also used for other purposes, for example, to control pedestrian movements, variable lane control (such as <a href="/en/Reversible_lane" title="Reversible lane" class="wl">tidal flow</a> systems or <a href="/en/Smart_motorway" title="Smart motorway" class="wl">smart motorways</a>), and railway <a href="/en/Level_crossing" title="Level crossing" class="wl">level crossings</a>.

Traffic lights, traffic signals, or stoplights – known also as robots in South Africa Traffic lights consist normally of three signals, transmitting meaningful information to drivers and riders through colours and symbols including arrows and bicycles. The regular traffic light colours are red, yellow , and green arranged vertically or horizontally in that order. Although this is internationally standardised, The method was first introduced in December 1868 on Parliament Square in London to reduce the need for police officers to control traffic. The system is also used for other purposes, for example, to control pedestrian movements, variable lane control , and railway level crossings. 