Science, Nature and Tech

Who on Earth Invented Traffic Lights?!

Every day we use hundreds of inventions without even thinking about it. In this series, we’ll be celebrating some of the most overlooked inventions, finding out what inspired their inventors and maybe even a few unexpected tales along the way.  Contributor Sally Anne asks… “Who on Earth invented… Traffic Lights?!”

You probably see these every day, in the car, on the bus or just walking down the road. They have the power to make people stop, yet they’re only a few coloured lights. Read on to find out about the explosive invention of traffic lights…


Our tale begins long ago, in Nottingham, in the year 1841. John Peake Knight aged just 12, had begun to work in the parcel room on the railways. John loved the railways and began to see how the signals used to control trains could be used on the roads.

By 1865, John had come up with a plan. Even though cars hadn’t been invented many people worried about the number of horse drawn carriages travelling through the streets! John approached the Metropolitan Police Commissioner, responsible for all the police in London, to suggest a way of controlling traffic on the city’s busy roads.

He had invented a system for controlling traffic on two busy roads outside the Houses of Parliament. The signal was inspired by those used for trains, with a long arm, which points at a different angle depending on whether you should go or stop. More importantly, he decided to use green and red lamps so it could be seen at night and so the traffic light was born.

Nevertheless, the signal was finally installed in December, 1868, with great success, slowing the traffic and making the roads safer. John, excited by this, was planning to expand his idea, taking traffic lights to all the busy cross roads in London. However, the lights were to meet a catastrophic end! Like most lights at that time, the green and red lamps were gas powered. One night, a month into the project, a small gas leak went unnoticed by the police officer who controlled the lights. The gas slowly built up, until finally the lamps exploded, badly hurting the police officer and destroying the signals.

Nobody felt like rebuilding the lights after such a disaster. It was 40 years before Earnest Sirrine, of Chicago, America, invented an automatic sign which turned to say Stop or Proceed. However, in 1912, the red and green lights were back when Lester Wire invented a new signal which used electric lights, much safer than the gas lights John had used. By the 1930s, John’s dream had finally come true, with traffic lights a common sight all over London and a part of everyday life today.

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