Competing patents
Following the accident, about four decades passed before traffic signals began to grow in popularity again, mainly in the United States as more automobiles hit the road. The early 1900s saw several patents being filed, each with a different innovation to the basic idea.
In 1910, Ernest Sirrine, an American inventor, introduced an automatically controlled traffic signal in Chicago. His traffic signal used two non-illuminated display arms arranged as a cross that rotated on an axis, according to Inventor Spot. The signs said "stop" and "proceed."
The first electric traffic light using red and green lights was invented in 1912 by Lester Farnsworth Wire, a police officer in Salt Lake City, Utah, according to Family Search. Wire's traffic signal resembled a four-sided bird-house mounted on a tall pole. It was placed in the middle of an intersection and was powered by overhead trolley wires. A police officer had to manually switch the direction of the lights.
However, the credit for the "first electric traffic signal" usually goes to James Hoge. A system based on his design was installed on Aug. 5, 1914, in Cleveland. Hoge received a patent for the system in 1918. (He had filed his application in 1913.) Hoge's traffic signal used the alternating illuminated words "stop" and "move" installed on a single post on each of the four corners of an intersection. The system was wired such that police and fire departments could adjust the rhythm of the lights in case of an emergency.
William Ghiglieri of San Francisco patented the first automatic traffic signal that used red and green lights in 1917. Ghiglieri's design had the option of being either automatic or manual.
Then in 1920, William Potts, a Detroit police officer, developed several automatic traffic light systems, including the first three-color signal, which added a yellow "caution" light.
In 1923, Garrett Morgan patented an electric automatic traffic signal. Morgan was the first African-American to own a car in Cleveland. He also invented the gas mask. Morgan's design used a T-shaped pole unit with three positions. Besides "Stop" and "Go," the system also first stopped traffic in all directions to give drivers time to stop or get through the intersection. Another benefit of Morgan's design was that it could be produced inexpensively, thus increasing the number of signals that could be installed. Morgan sold the rights to his traffic signal to General Electric for $40,000.
The first electric traffic light in Europe was installed in 1924 at Potsdamer Platz in Berlin, according to Marcus Welz, CEO of Siemens ITS (Intelligent Traffic Systems) US. The five-sided traffic light was mounted on a tower and was primarily manual with some automation, which only required a single police officer to manage. A replica now stands nearby and is a popular tourist attraction.
Pedestrian signals began to be included on traffic signals in the 1930s, according to the U.S. Department of Transportation. A "Walk/Don't Walk" signal was first tested in New York in 1934. It even used an upright palm to indicate "Stop."
John S. Allen, an American inventor, filed one of the earliest patents in 1947 for a dedicated pedestrian traffic signal. Allen's design had the pedestrian signal mounted at curb level. Allen also proposed that the signals could contain advertisements. In his application, he explained that the words "Stop" and "Go" could be followed by the word "for," which in turn would be followed by a brand name.