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| Detroit police officer William Potts, inventor of the three-way traffic light |
In the absence of something fresh, I'm taking the liberty of re-posting something of mine from another site.
The History of Traffic Lights
by Michael Daisy
You see them hanging around, here and
there. They’re everywhere, part of the landscape, it seems but you never really
pay close attention to them until you blow through a red one.
Traffic lights. Webster’s defines
them as “a set of automatically operated colored lights, typically red, amber,
and green, for controlling traffic at road intersections and crosswalks.”
Without traffic lights, urban life would
be a lot more chaotic than it is. No doubt bloodier, too.
Traffic lights as regulators of traffic
flow evolved from road signs – those ubiquitous objects on the sides of roads
that provide essential, often useful, and frequently annoying information. Road
signs, of course, came on the scene sometime after the development of roadways,
which developed to accommodate vehicular and military traffic.
The oldest known constructed roads are
stone paved streets at Ur, between the Tigris and Euphrates rivers in present
day Iraq, and date to around 4000 BC. All of our traffic signs trace their
origins to Roman milestones. As the name suggests, these were usually large
stone columns placed at intervals of one mile (occasionally portions of a mile)
and contained directions and the distance remaining to Rome; the origin of the
old saying “All roads lead to Rome.”
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| Roman Milestone |
In the middle ages, road signs evolved
into multidirectional indicators that directed travelers to distant villages
and towns, and sometimes included distances to specific destinations. Automobile
traffic signs began appearing on roadsides not long after the introduction and
proliferation of the automobile.
The red, green, and amber colors used by
traffic signals are nature-based and have evolved from nautical right-of-way,
and railroad usage.
Almost from the very beginning, Red has
been the color of choice for “Stop.” Red, the color of blood, is considered a
hot, or “dangerous” color. It elevates blood pressure, and heightens nervous
tension. The shade of red used in most traffic signals contains orange hues to
improve its visibility by individuals with vision issues, such as color
blindness.
On a color wheel, Green is the polar
opposite of red, and a seemingly natural choice for “Go.” Green is a calming
and welcoming, and hence, inviting color. According to some sources, the use of
green as a “go” signal for car traffic is a carryover from railroads, which
adopted the color because white light was not sufficiently discernible during
daylight hours. Like red, the color green in most traffic signals is enhanced.
It includes some blue for the benefit of colorblind individuals.
Yellow, or amber, the color of “Caution,”
is the most visible color in the spectrum. It can be seen from the greatest
distance.
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| Railroad Semaphore |
The world’s very first traffic light was
installed for the benefit of pedestrians, not traffic and was inspired by the
1102 fatalities and 1334 injuries documented on London roads in 1866. Invented
by John Peake Knight (1828-1886), a railway engineer from Nottingham, the
signal was installed at the busy intersection of Great George and Bridge
Streets near Parliament in London on December 10, 1868. It was based on railway
signals then in use, and manufactured by Saxby and Farmer, a leading railway
signal manufacturer. Mounted on a tall pillar, it featured three semaphore arms
provided with red and green gas lamps for nighttime use, and was operated by a
police constable. It was an instant success.
Unfortunately, the signal was destroyed
just over three weeks later, on January 2, 1869, by an explosion caused by a
leaky gas valve that resulted in the death of the police officer operating the
device. Knight’s signal was declared a public safety hazard and ordered
removed. It would be another 60 years, 1929, before an electrified variation of
Knight’s traffic signal would be reintroduced to London streets.
The next chapter in the development of
the traffic light took place in Chicago in 1910, when Earnest Sirrine
introduced what is believed to be the first automatically controlled traffic
signal. The device used two separate display arms that rotated on an axis
between two fixed positions. The display arms were arranged as a cross with one
display continually offset from the other by 90-degrees. In place of red and
green lights, Sirrine’s “street traffic system” used the non-illuminated words
“stop” and “proceed.”
Two years later, Lester Farnsworth Wire
(1887-1958) – a detective with the Salt Lake City Police Department – invented
a traffic light that used red and green lights. It was powered from overhead
trolley wires. The following year, 1913, James Hogue received a patent for a
manually controlled red and green-lighted traffic signal that was installed in
1914 at 105th Street and Euclid in Cleveland. Its big advantage lay
with the ability of police and/or fire personnel to adjust the rhythm of
operation as necessary in the event of emergency.
William Ghiglieri of San Francisco
received a patent on May 1, 1917 for the first automatically operated traffic
signal employing red and green colored lights that included an option to allow
manual operation. Then in 1920, Detroit cop William Potts (1883-1947) invented
electrically powered, hanging, automatic traffic lights to control four-way
intersections. Potts signals were the first to include amber “caution” lights
and were installed at several busy intersections along Woodward Avenue, still
the Motor City’s main drag.
In 1923, Garrett Augustus Morgan Sr.
(1877-1963) – the inventor of a “respiratory protective hood” that was the
forerunner of the gas mask, and the first African-American to own an automobile
in Cleveland OH – received a patent for a reliable and inexpensive manually
operated signal. Shortly after being awarded the patent, Morgan sold his rights
to General Electric for $40,000 (currently the equivalent of more than a
half-million dollars). GE used the patent for protection in a failed effort to
establish a traffic light monopoly.
Meanwhile around this time in Motor City,
home of Henry Ford and the Model-T, the first traffic tower in the US was
installed at the intersection of Woodward and Michigan Avenues in 1917. As they
began being used in other cities, the towers assumed a wide variety of shapes
and sizes, but were generally big, tall, right in the middle of all the traffic
action, and therefore, VERY visible. These traffic controlling structures were
often manned, but not necessarily so, and were available with or without
traffic lights.
Laying claim to the world’s oldest
operating traffic light is the city of Ashville OH. The light in question
controlled traffic from its installation at the corner of Main and Long Streets
for about 50 years. Designed by Ashville resident Teddy Boor, the signal
featured a slowly rotating hand that swept across the face of each light to let
drivers know how much time remained before a light change. The signal was
ordered removed in 1982 by the Ohio Department of Transportation, which ordered
the then village to replace it with a standard traffic light.
While it is no longer controlling car
traffic, the light is still operating, and directing foot traffic inside the
Ashville Museum, where it is the most popular exhibit. According to officials,
“there is plenty of foot traffic.” The light has also been featured on Oprah
and An American Moment With James Earl Jones.
In a related sidebar, the first automated
pedestrian signs featuring a lighted “don’t walk” signal were installed in New
York City on February 5, 1952.
And finally, what would be the point of
having a car without driving endlessly around in search of parking spaces and
metering devices?
Carlton Cole “Carl” Magee – an attorney,
publisher, and United States Senator from New Mexico – was awarded a patent for
the first parking meter in 1935. The company he founded, the Magee-Hale
Park-O-Meter Company, continues to manufacture most of the parking meters in
use in the United States.
The father of the parking meter is an
attorney and member of congress? It figures.
Sources:
About.com
AshvilleOhio.net
BBC
DidYouKnow.com
FindAGrave.com
MarkTraffic.com
MunicipalSigns.com
OnlineUtah.com
Rothe, Christopher A. J.D.; “Using
Patents to Advance The Civil Engineering Profession;” American Society of Civil
Engineers/Civil Engineering Magazine, June 2006, Vol 76, No. 6, pg. 70
Signalfan.com
StraightDope.com
Suite101.com
Technology Transfer Program, UC Berkeley
TheVictorianst.com
WikiAnswers
Wikipedia
Yahoo! Answers
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