On this day in engineering history, the first signaling
device for regulating street traffic was installed. Designed by John Peake
Knight, an engineer for the London, Brighton & South Coast Railway Company,
the first traffic signal was quite different from the electric, solar-powered and LED traffic
lights that are now a common sight in many parts of the world.
J.P. Knight's
invention had two movable arms that signaled "stop" when extended horizontally
and "caution" when arranged at a 45-degree angle. At night, red and green gas
lights supplemented the arms to signal "stop" (red) or "caution" (green) for
both horse-drawn conveyances and pedestrians.
Railway Semaphores
Installed at the intersection of George and Bridge Streets
near London's Houses of Parliament, J.P.
Knight's traffic signal was informed by Britain's railway heritage. The
semaphore, one of the earliest types of fixed railroad signals, had been
introduced to the London and Croydon Railway
(predecessor of the London,
Brighton & South Coast Railway) by Charles Hutton Gregory in 1842.
Gregory,
who later served as president of Britain's Institution of Civil
Engineers, favored a semaphore design with pivoting arms or blades and a
spectacle with colored lenses. At night, these lenses were moved in front of a
gas lamp to signal trains. The first railroad semaphores were made of wood, but
subsequent designs used metal.
Honoring the Right
Inventor
Although Garrett Augustus Morgan is often credited with
designing the first traffic signal, the American inventor cannot lay claim to
an honor that rightly belongs to J.P. Knight. Moreover, in the United States
alone, there were more than 60 traffic signals patented before Garret Augustus
Morgan's design of a cross-shaped traffic signaling device in 1922.
Even if
J.P. Knight's accomplishment is limited to the distinction of being "the first
traffic signal in Britain",
Garrett Augustus Morgan is still not the inventor of the first electric traffic light in the United States. Contenders
for that honor include, among others, Lester Wire of Salt
Lake City, Utah (1912) and James
Hoge of Cleveland, Ohio (1914).
Resources:
http://www33.brinkster.com/iiiii/trfclt/
http://en.wikipedia.org/wiki/J._P._Knight
http://en.wikipedia.org/wiki/Railway_semaphore_signal
http://en.wikipedia.org/wiki/Charles_Hutton_Gregory
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Re: December 10, 1868 – The First Traffic Signal
