Electric Railroad

Electric railroad is an electrically powered railway system. Electrically powered trains include high-speed passenger trains; some freight trains; and the subways, elevated systems, and streetcars found in certain cities. The electricity to run an electric train comes from an external source--a central power plant--rather than from an engine or generator on board the train.

The propulsion system of an electric train includes the traction motor and the driving wheel. The traction motor turns the driving wheel, which actually makes the train move.
From The World Book^™ Multimedia Encyclopedia ©1998 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved.
World Book illustration by William Graham.

Electric trains have many advantages. They are quieter than other trains and do not produce smoke or exhaust. Coal, gas, oil, nuclear power, or water power can generate electricity for an electric train. In contrast, diesel trains run only on diesel oil. Electric trains also travel faster than any other trains. The world's fastest is France's TGV (train a grande vitesse, or high-speed train). It travels up to about 185 miles (300 kilometers) per hour. Some Japanese electric trains run up to about 160 miles (260 kilometers) per hour. Engineers are developing faster electric trains called maglev (magnetic levitation) trains. German and Japanese models of these trains test from about 250 to 310 miles (400 to 500 kilometers) per hour.

Electric railroads provide intercity service (service between cities). These railroads also offer intra-urban or commuter service, which carries passengers within cities and between cities and their suburbs. Electric railroads are common in many European countries and in Japan. However, in the United States only about 1 per cent, or 2,000 miles (3,200 kilometers), of intercity track is electrified.

Kinds of electric railroads. Most intercity electric trains receive power through an overhead wire called a catenary. In the overhead wire system, a steel framework connects a car, usually a locomotive, to a catenary. The framework, called a pantograph, delivers electric current from the wire to the locomotive's propulsion system. This system includes the traction motors. Traction motors power the driving wheels, which actually move the locomotive.

An electric train receives power from a catenary (overhead wire) or from an electrified third rail. In the overhead wire system, shown, a pantograph conducts electricity to the transformer. The current eventually arrives at the traction motors, which are part of the train's propulsion system.
From The World Book^™ Multimedia Encyclopedia ©1998 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved.
World Book illustration by William Graham.

Intercity electric trains have one or more locomotives that pull freight or passenger cars. Most electric locomotives weigh between 100 and 200 short tons (90 and 180 metric tons) and provide about 6,000 to 7,000 horsepower (4,500 to 5,200 kilowatts). They can reach speeds of over 150 miles (240 kilometers) per hour.

An electrified third rail delivers electricity to most intra-urban electric trains. Trains using a third rail have metal plates called shoes. Two shoes attach to the bottom of a locomotive or railcar. The shoes slide along the third rail, delivering electric current to the car's propulsion system.

Some intra-urban railcars have traction motors, which range from 119 to 282 horsepower (89 to 210 kilowatts). Others are driven by locomotives or by railcars that have traction motors. Intra-urban railcars reach speeds of about 50 to 75 miles (80 to 120 kilometers) per hour.

Unlike most electric trains, a maglev train has little or no contact with a track or wires. Maglev trains have special magnets in the bottom of the cars. The magnets in the cars and electrically charged coils in the guideway (track) create a powerful magnetic force. This force lifts the cars above the guideway. Separate electric currents in the coils create a shifting magnetic field that propels the train forward. Some maglev trains test at high speeds. But only low-speed maglev trains were in use in the early 1990's, serving parts of Europe.

History. In the early 1800's, the Scottish inventor Robert Davidson built the first full-sized electric locomotive. But the high cost of producing electricity made it too expensive for general use by railroads. The development of the electric generator in the mid-1800's made the modern electric railway possible. This device generated a current of high voltage at low cost.

The first commercial electric street railway began operation in Lichterfelde, Germany, in 1881. In 1887, Frank J. Sprague, an American inventor, built the Union Passenger Railway in Richmond, Va. This was the first large electric railway system. By the early 1900's, electric elevated trains operated in Chicago, Boston, and New York City. Europe built many electric intercity tracks in the late 1940's. The first modern high-speed electric train began running in 1964. It was Japan's Shinkansen, also called the "bullet train." France's TGV began service in 1981.

Contributor: Vernon P. Roan, Ph.D., Prof. of Mechanical Engineering, Univ. of Florida.

Electric Railroad

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