How the First Traffic Signal Predated the First Car

I’m back with the full story behind anotherof the interesting facts I’ve been compiling for an upcoming interactive. We’ll be launching the project later this month, so make sure to check back for more updates. Until then, I hope you enjoy this quick tale!
Did you know that the world’s first traffic signal predated the automobile by almost 20 years?
Traffic has been causing headaches seemingly as long as man has been on the move. In ancient Rome, congestion was so bad that wheeled vehicles were banned from the city during daytime hours. More than 18 centuries later, the Industrial Revolution saw an explosion in urban populations that left many city streets overcrowded and dangerous. Not surprisingly, finding a way of easing this congestion of wagons, buggies and humans became increasingly important during the late 19th century.
No city on earth was more in need of help than London, England, already home to 1 million people. In 1866 alone more than 1,100 people were killed (and another 1,300 were wounded) in traffic accidents. With the public clamoring for a solution, British railway engineer and superintendent John Peake “J.P.” Knight testified before the British House of Commons on the need to control traffic on the city’s busy, congested streets. Parliament approved, providing funds for Knight to engineer a solution.
His resulting concept was quite simple. Intended to mimic the arm movements of police manually directing traffic, his design was a tall pole with two semaphore arms—one that extended horizontally to signal “stop,” and another set at a 45-degree angle to signal “caution.” For nighttime usage, Knight added a gas lantern on top of the pole, which indicated green for go and red for stop. The signal system was man-operated, requiring an attendant to monitor traffic and turn a lever at the signal’s base to notify drivers. Concerned that drivers and pedestrians would not heed just anyone, officials decided that police officers would handle the signal’s operation.
Knight’s invention was installed at the corners of Great George and Bridge Streets, just off London’s Parliament Square, and began operations on December 10, 1868. The traffic signal seemed to be an immediate success, but tragedy struck just three weeks later. On January 2, 1869, a leak in the signal’s gas valve caused an explosion, severely injuring its police attendant. In the accident’s aftermath, new fears for public safety caused officials to remove the signal, ending this early attempt at transportation control almost as quickly as it had started.
Modified versions of this early traffic signal would be developed over the coming decades, but it would be 45 years before the first electric traffic light came along. On August 5, 1914, a series of red and green lights were installed on a busy street corner in Cleveland, Ohio. Officials were able to control the flow of traffic in all directions by coordinating among the four signals. These signals were also man-operated, albeit from the safety of nearby control booths.