Decline in Usage On Railways
All trolleybuses use trolley poles, and thus trolley poles remain in use worldwide, wherever trolleybuses are in operation (currently, some 315 cities), and several manufacturers continue to make them, including Vossloh-Kiepe, Škoda and Lekov.
However, on most railway vehicles using overhead wire, the trolley pole has given way to the bow collector or, later, the pantograph, a folding metal device that presses a wide contact pan against the overhead wire. While more complex than the trolley pole, the pantograph has the advantage of being almost free from dewiring, being more stable at high speed, and being easier to raise and lower automatically. Also, on double-ended trams, they eliminate the need to manually turn the trolley pole when changing direction. The use of pantographs (or bow collectors) exclusively also eliminates the need for wire frogs (switches in the overhead wiring) to make sure the pole goes in the correct direction at junctions.
Apart from heritage streetcar lines, very few tram/streetcar systems worldwide continue to use trolley poles on vehicles used in normal service. Among the largest exceptions are the streetcar systems of Toronto, Ontario; Philadelphia (the "Subway-Surface" lines and route 15); Riga, Latvia, Kolkata (formerly Calcutta), India and Alexandria, Egypt. Smaller systems still using trolley poles for regular service include Hong Kong Tramways, the Daugavpils, Latvia system, and Rio de Janeiro's Santa Teresa Tramway.
These systems and a few others worldwide retain use of trolley poles, even on new streetcars, in order to avoid the difficulty and expense of modifying long stretches of existing overhead wires to accept pantographs. Trams or light rail cars equipped with pantographs normally cannot operate on lines with overhead wiring designed for trolley-pole collection. It is possible to construct overhead wiring that is capable of accommodating both trolley poles and pantographs, but such designs are more expensive to maintain and are generally seen only in cities where modern streetcars or light rail cars share tracks with preserved historic cars.
Read more about this topic: Trolley Pole
Famous quotes containing the words decline, usage and/or railways:
“Where mass opinion dominates the government, there is a morbid derangement of the true functions of power. The derangement brings about the enfeeblement, verging on paralysis, of the capacity to govern. This breakdown in the constitutional order is the cause of the precipitate and catastrophic decline of Western society. It may, if it cannot be arrested and reversed, bring about the fall of the West.”
—Walter Lippmann (1889–1974)
“...Often the accurate answer to a usage question begins, “It depends.” And what it depends on most often is where you are, who you are, who your listeners or readers are, and what your purpose in speaking or writing is.”
—Kenneth G. Wilson (b. 1923)
“There is nothing in machinery, there is nothing in embankments and railways and iron bridges and engineering devices to oblige them to be ugly. Ugliness is the measure of imperfection.”
—H.G. (Herbert George)