While waiting to cross the street at busy intersections, have you ever wondered who invented the traffic light? Most people credit the first traffic light to Nottingham engineer John Peake Knight. A railway manager, Knight specialized in designing the signaling system for Britain’s growing railway network in the 1860s. He saw no reason why this could not be adapted for use on the busy London intersections. Thus, he proposed a signaling system based on the railway movable-arm signal: Arms extending horizontally commanded drivers to stop, whereas arms lowered to a 45-degree angle told drivers to move on, resembling a traffic director’s gestures. Red and green gas lamps were added to the signal for use at night. A police officer was stationed by the side to operate the system.
Knight’s traffic signal was installed near London’s Westminster Bridge in December 1868, but the system was short-lived. A gas leak one month later caused an explosion in the lights, injuring the policeman operating it. Deemed a public hazard, the project was immediately dropped, and traffic lights were banned until their return in 1929 back to the British streets.
In the early 1900s, versions of the British traffic lights appeared in big cities in America, where traffic was on a sharp rise. Systems using movable arms were popular in Chicago, while those using the red and green lights were adopted in San Francisco. Patents with innovations on Knight’s ideas were filed nationwide. A major breakthrough was the yellow light invented by a Detroit police officer William Potts. Installed in Detroit in 1920, Potts’ three-color system allowed for the added signal “proceed with caution” to be displayed.
Now, with the emergence of self-driving cars, researchers have begun to suggest that traffic signals are no longer necessary. Intersections will operate in a way that cars automatically adjust their speed to cross through, while maintaining safe distances from other vehicles. In the near future, we may experience a brand new form of traffic management!