Overhead Catenary
A catenary is a system of overhead wires used to supply electricity to a locomotive, streetcar, or light rail vehicle which is equipped with a pantograph.
Unlike simple overhead wires, in which the uninsulated wire is attached by clamps to closely spaced crosswires supported by poles, catenary systems use at least two wires. The catenary or messenger wire is hung at a specific tension between line structures, and a second wire is held in tension by the messenger wire, attached to it at frequent intervals by clamps and connecting wires. The second wire is straight and level, parallel to the rail track, suspended over it as the roadway of a suspension bridge is over water.
Simple wire installations are common in light rail, especially on city streets, while more expensive catenary systems are suited to high-speed operations.
The Northeast Corridor in the United States has catenary over the 600 miles (1000 km) between Boston, Massachusetts and Washington, D.C. for Amtrak's high-speed Acela Express and other trains. Commuter rail agencies including MARC, SEPTA, NJ Transit, Metro-North utilize the catenary to provide local service.
In Cleveland, Ohio the interurban/light rail lines and the heavy rail line use the same overhead wires, due to a city ordinance intended to limit air pollution from the large number of steam trains passing through Cleveland between the east coast and Chicago. Trains switched from steam to overhead catenary electric locomotives at the Collinwood Rail Yards about 10 miles (16 km) east of Downtown and similarly at Linndale on the west side. When Cleveland constructed its rapid transit (heavy rail) line between the airport, Downtown and beyond it employed similar overhead catenary technologies that the railroads used, and were able to utilize railroad electrification equipment left over after railroads switched from steam to diesel locomotives. Light and heavy rail public transit systems share trackage for about 3 miles (4.8 km) along the Cleveland Hopkins International Airport Red (heavy rail) line, Blue and Green interurban/light rail lines between Cleveland Union Terminal and just past East 55th Street station, where the lines separate.
Part of the Boston, Massachusetts Blue Line through the northeast suburbs uses overhead lines.
Read more about this topic: Overhead Line
Famous quotes containing the word overhead:
“There’s something wonderfully exciting about the quiet sing song of an aeroplane overhead with all the guns in creation lighting out at it, and searchlights feeling their way across the sky like antennae, and the earth shaking snort of the bombs and the whimper of shrapnel pieces when they come down to patter on the roof.”
—John Dos Passos (1896–1970)