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Are You Ready for a Revolution? The History and Future of Traffic Lights

The modern traffic signal is an ever-present fact of life for motorists, but controlling traffic flow through green and red indicators was an idea pioneered long before motor vehicles were the standard mode of ground transportation. In 1868, J.P. Knight — a British engineer and inventor — developed a traffic signal in order to reduce the number of accidents on busy London streets, where horse-drawn carriages and carts, along with pedestrians, ruled the roads. Knight’s invention used semaphores to signal which directions of traffic should stop and which should proceed through an intersection, and at night, the police-operated device used red- and green-colored gas lamps to indicate the same instructions.

Knight’s traffic signal was abandoned in 1869 after one of the gas lamps exploded, injuring the traffic control officer, and traffic signals wouldn’t appear in London again for 50 years. But by the early-1900s in the United States, the growing number of motor vehicles sharing streets with horse-drawn traffic and pedestrians forced other inventors into action. From Lester Wire’s first electric traffic signal in Salt Lake City in 1912 to Garrett Morgan’s famous patent in 1923, America led the way in the development of modern traffic control devices. We had no other choice. The rapid adoption of automobiles as a preferred method of travel spurred the innovation of control devices that were desperately needed by municipal and state governments adjusting to a new normal.

Historically, however, automobiles and infrastructure have operated independently of each other. The driver has interpreted the language of the infrastructure and — at risk to himself and others — may ignore the direction of traffic lights and posted directions, limits and warnings if he so chooses. Even vehicle detection systems, which can make our signals operate more responsively and effectively, simply interpret vehicle presence and behavior.

Recent History of Traffic Signals

In 2017, 105 years after the first electric traffic signal was installed in Utah, we are again facing a revolution in traffic that presents bothindustry and government with challenges and opportunities. True autonomous, driverless vehicles are far from science fiction, and the first freight and transit applications are being piloted around the country. Infrastructure can no longer afford to be passive, and since innovation rarely waits for regulation, governments cannot afford to take a wait-and-see approach.Fortunately, connected vehicles — those that feature advanced communication capabilities but rely on traditional driver operation — will serve as a bridge between the familiar past and a driverless future. Standards for transferring data to and from vehicles and infrastructure are being set, and traffic technology innovators are working with states and municipalities across the United States to provide better information to drivers from the infrastructure, and to the infrastructure from the cars on the road. While those parties are working to determine which data sets are of most use to both motorists and traffic control systems, there’s no doubt that the connected-vehicle revolution is upon us. Over the next decade, we’ll see exceptionally rapid development and deployment of connected technologies at rates not experienced by the traffic industry in 100 years.


For traffic professionals, it’s critical to begin considering the impact of connected vehicles and infrastructure into both short- and long-term management plans. The industry may still be developing solutions — answers to questions that seemed outlandish just a decade ago — but we should begin to prepare today by researching and investing in powerful, modular platforms that are specifically designed to bridge the gap between traditional solutions and cars of the future.

Because it won’t be long before the most common motorist complaint changes from, “I’m sitting on the side street and no one is on the main street,” to, “Why aren’t your signals providing my new car with real-time travel-time information and signal status?”