This diagram shows how a traditional traffic light works.
Picture 1: A red light means stop.
Picture 2: A green light means go.
Picture 3: A yellow light means slow down and be ready to stop.
Traffic lights (or traffic signals) are lights used to control the movement of traffic. They are placed at road intersections and crossings. The different colors of lights tell drivers what to do.
Light cycles
Traffic lights change their colors in the same order every time. In most English-speaking countries, traffic lights usually change in this order:
- Red light on: This tells drivers to stop.
- Green light on: This means the driver can start driving or keep driving.
- Yellow light on: This tells drivers to stop when it is safe to, because the light is about to turn red.
Lester Wire was credited with the invention of the electric traffic light in 1912 in Salt Lake City, Utah. Garrett Morgan, an African-American inventor, also developed a traffic signaling system, and was one of the first people to get a patent for a traffic light.
William Potts, a police officer, invented the first traffic light with three colors.
Images for kids
A traffic light for pedestrians in Switzerland
An early two-light traffic signal by White Horse Tavern in Hudson Street, New York. Image taken in 1961
A traffic light in Stockholm in 1953.
Traffic lights can have several additional lights for filter turns or bus lanes. This one designed by David Mellor introduced in 1965 and is used across the United Kingdom, Crown Dependencies and British Overseas Territories, which also shows the red + orange combination seen in a number of European countries, and a backing board with white border to increase the target value of the signal head. Improved visibility of the signal head is achieved during the night by using the retro-reflective white border.
Horizontally mounted signals in Japan
A traffic light for pedestrians depicting Miffy and with white LED as countdown to green in Utrecht, Netherlands
Bicycle traffic lights in Vienna
Four-lamp public transport traffic light in Moscow, Russia, showing "stop" signal.
A tram signal in Geneva, Switzerland.
Swedish traffic light (left) for use by public transport vehicles only. All signals use white lighting and special symbols ("S", "–" and an arrow) to distinguish them from regular signals. The small light at the top tells the driver when the vehicle's transponder signal is received by the traffic light.
Tram traffic lights at a tramway junction in Hong Kong
A traffic light in Westbrook, Maine, on State Route 25. Notice the red arrow to the left of the two green straight lights.
Lane control signals installed on the Old Champlain Bridge in Montréal, QC.
Historic dummy light in Canajoharie, New York, United States
An example of a LED traffic light in Australia
An animated GIF shows a traffic light in 3 phases
Temporary traffic light near Hazlerigg, England
California attempts to discourage red light running by posting the minimum fine.
A driver comes to a stop on the crosswalk beyond the stop line as a result of attempting to avoid a red light violation
Traffic light in Chelyabinsk, Russia showing a green light with a digital countdown (in the centre aspect) of the time left until the signal switches to amber.
An intersection with blue confirmation lights in Newport News, Virginia
Traffic light with time in Tehran, Iran
An example of a wire-mounted traffic light in Fort Worth, Texas.
A typical traffic light on Ninth Avenue in New York City. Note that the traffic light gantry is of a guy-wire masted style, which is unique to New York City.
A vertically mounted traffic light in Boston.
Example of horizontally mounted traffic light in Trenton, New Jersey.
Horizontally mounted traffic lights in Calgary, Alberta.
A bulky tubular metal structure. Not only is the intersection very large, but due to its location on Florida's east coast, the traffic lights must be hurricane resistant.
Angled mast-arms, which were frequently used in the state of Pennsylvania during the 1960s and 1970s.
Three horizontally mounted traffic lights for visibility under a bridge in King of Prussia, Pennsylvania. Pennsylvania typically mounts traffic lights vertically.
LED traffic light (using cap visors)
Temporary LED traffic lights with sensor in Australia
Temporary traffic light in the United Kingdom
Traffic light in a small intersection in Hagerstown, Maryland (using tunnel visors)
Example of traffic signals mounted on gantries in downtown Cincinnati, Ohio, and integrated with street signage
Typical set of traffic lights in East Lansing, Michigan
Typical example of traffic lights mounted on a wide street in California
One example of traffic lights on a suburban street in Santa Clarita, California
LED traffic lights in Örnsköldsvik, Sweden
Typical set of traffic lights in Spain
The green on top light in Tipperary Hill, Syracuse, New York
LED pedestrian signal in New York City
Traffic light in Ashgabat, Turkmenistan
A Marshalite traffic signal, as formerly installed at various intersections in Melbourne, Australia, indicating how much time remained before a signal change.
East Rembo Buting Intersection Traffic light near Kalayaan Ave.
A U-turn traffic light in Lake Buena Vista, Florida.
See also
In Spanish: Semáforo para niños
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Traffic light Facts for Kids. Kiddle Encyclopedia.
