Red, green, yellow&#; three-color traffic lights are now a daily part of every person&#;s life. But it wasn&#;t always like that.
While their presence in city centers is now being questioned, they still fulfill an essential function by regulating the competing flows of traffic at an intersection.
Let&#;s take a look at a hundred and fifty years of history!
December 10, : the official birth date of the world&#;s first traffic light. It was installed at Parliament Square in London. The system was composed of two mobile signs attached to pivoting arms that were manipulated by a lever. The post was topped with a gas-lit semaphore to ensure visibility. But it was short-lived. Less than two months later, the traffic light exploded, killing the police officer who worked the signs.
The world had to wait 46 years until electricity use became widespread before the first dual-colored traffic light, using this new energy, was installed in Cleveland in the United States. Detroit and New York added yellow between red and green in . The traffic lights that we now know were born and became the norm throughout the world.
In , the first mechanical traffic light using electricity was installed in Paris at the intersection of Boulevard de Strasbourg and Grands Boulevards. Most of Europe&#;s largest cities soon followed suit: Berlin in , Milan in , Rome in , London in , Prague in , Barcelona in &#; And the system was exported to Tokyo in .
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The first Convention on the Unification of Road Signals was signed in Geneva on March 30, . Its goal was to increase road traffic safety and facilitate international movement by road through a uniform system of road signals. The majority of signs that we recognize today were defined through this treaty. Traffic lights with three colors (red, yellow, green) became the standard.
On November 20, , the U.S. Patent Office grants Patent No. 1,475,074 to 46-year-old inventor and newspaperman Garrett Morgan for his three-position traffic signal. Though Morgan&#;s was not the first traffic signal (that one had been installed in London in ), it was an important innovation nonetheless: By having a third position besides just &#;Stop&#; and &#;Go,&#; it regulated crossing vehicles more safely than earlier signals had.
Morgan, the child of two formerly enslaved people, was born in Kentucky in . When he was just 14 years old, he moved north to Ohio to look for a job. First he worked as a handyman in Cincinnati; next he moved to Cleveland, where he worked as a sewing-machine repairman. In , he opened his own repair shop, and in he added a garment shop to his operation. The business was an enormous success, and by Morgan had made enough money to start a newspaper, the Cleveland Call, which became one of the most important Black newspapers in the nation.
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Morgan was prosperous enough to have a car at a time when the streets were crowded with all manner of vehicles: Bicycles, horse-drawn delivery wagons, streetcars and pedestrians all shared downtown Cleveland&#;s narrow streets and clogged its intersections. There were manually operated traffic signals where major streets crossed one another, but they were not all that effective: Because they switched back and forth between Stop and Go with no interval in between, drivers had no time to react when the command changed. This led to many collisions between vehicles that both had the right of way when they entered the intersection. As the story goes, when Morgan witnessed an especially spectacular accident at an ostensibly regulated corner, he had an idea: If he designed an automated signal with an interim &#;warning&#; position&#;the ancestor of today&#;s yellow light&#;drivers would have time to clear the intersection before crossing traffic entered it.
The signal Morgan patented was a T-shaped pole with three settings. At night, when traffic was light, it could be set at half-mast (like a blinking yellow light today), warning drivers to proceed carefully through the intersection. He sold the rights to his invention to General Electric for $40,000.
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