Who Invented Traffic Lights?
Long before roads needed traffic lights, railways were using a system of signals to control train traffic. In the early railways, a single track was used for both up-going and down-going trains, and safety depended on spacing the arrival and departure of trains according to time intervals.
These signals consisted of a ball and something that looked like a kite. When the kite was raised on top it indicated danger while if the ball was raised, it indicated the all clear.
In 1841, the first semaphore (visual form of signalling) railway signal was installed at London station. This consisted of a signal arm in a horizontal position to express ‘stop’. If lowered to 45 degrees it urged the engine driver to proceed with caution and if pointed vertically skyward it indicated the track was clear. The signals were painted red as it was easy to identify and attract the driver’s attention.
At night, oil lamps were added on top of these poles and a red light indicated ‘stop’ while a white light indicated that the driver could proceed.
However, the white coloured light proved disastrous as it stood for both ‘the all clear’ and ‘warning indications’ and so resulted in many accidents.
In January 1876, the engine driver of the Flying Scotsman, an express train, rammed into a freight train running ahead on the same track because of the confusion in the signals. The derailment blocked the track in the opposite direction. This caused a major accident as the Manchester express train, which was running on this track, crashed into the already derailed bogies, killing 13 people and seriously injuring 24 others.
Following this disastrous accident, the signal system was modified. First, the normally displayed indication for ‘stop’ became red while an additional yellow light was added to indicate to the driver to proceed with caution. In 1893, green lights replaced the white light to avoid confusion as street lighting and house lighting hampered the driver from reading the signal rightly.
Since railway signalling was introduced, civic officials decided to try it out in the congested streets of London. Thus, even before the advent of motorcars, traffic lights were introduced in 1868 in London to control the flow of horse buggies, wagons and pedestrians.
This signal was a revolving lantern with red and green signals. Red meant ‘stop’ and green meant ‘caution’. The lantern was lit by gas and turned up by means of a lever at its base so that the appropriate light faced the traffic.
But in an unfortunate incident this traffic light exploded, on January 2, 1869, injuring the policeman who was operating it.
With automobiles being introduced in America and Britain the traffic situation was getting problematic. A police officer called William Potts of Detroit, Michigan, decided to do something about the problem and he decided to adapt railroad signals for street use.
His real problem was that rail traffic ran along one way while traffic flow at intersections ran at right angles and were four-way.
Nevertheless, he used two-coloured lights, red and green, and connected the signals by electricity. The first traffic light was thus installed in 1920 on the corner of Woodward and Michigan Avenues in Detroit.
But these lights were manually operated and were still two-way lights. At about the same time, Garrett Augustus Morgan Sr., an African-American, from Cleveland, Ohio, realized the need for traffic lights after seeing a collision between an automobile and a horse-drawn carriage.
Distressed by the accident he decided to do something about it and on November 20, 1923 patented the four-way traffic light signal.
Today, traffic lights have an internal timer that is programmed to stay on for a specific amount of time. Policemen also control the lights on certain roads depending on the amount of traffic.
Morgan’s invention has indeed saved many thousands of lives and created vehicular order among chaos. So next time you wait at a red light, Relax, and thank Garrett Augustus Morgan for his invention.
Category: 5 Ws & HTags: horizontal • horse • london • train < Previous Post | Next Post >