Trolley Pole - Decline in Usage On Railways

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:

    Families suffered badly under industrialization, but they survived, and the lives of men, women, and children improved. Children, once marginal and exploited figures, have moved to a position of greater protection and respect,... The historic decline in the overall death rates for children is an astonishing social fact, notwithstanding the disgraceful infant mortality figures for the poor and minorities. Like the decline in death from childbirth for women, this is a stunning achievement.
    Joseph Featherstone (20th century)

    Pythagoras, Locke, Socrates—but pages
    Might be filled up, as vainly as before,
    With the sad usage of all sorts of sages,
    Who in his life-time, each was deemed a bore!
    The loftiest minds outrun their tardy ages.
    George Gordon Noel Byron (1788–1824)

    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)