Structures
A crossing pylon is used for crossing over a body of water or a valley. Due to the long span, crossing pylons across rivers and sea straits are frequently taller than standard pylons. They may have marking lamps, and unlike standard pylons, often have stairways for easy access to the top. In many cases, their height makes them ideal for carrying radio antennas and transmitting equipment.
Crossing pylons for valleys, depending on the local topography, are not necessarily tall, but the distance between the conducting cables must be sufficient to prevent high winds knocking the conductors into one another; these pylons have wide crossbars to prevent this. For very long spans each phase has a separate pylon, particularly if the pylons are short.
Special crossing pylons are often used where aerial tramways cross power lines. These pylons are designed with integral scaffolding so that the tramway cars can be reached without touching a live power line. This enables passengers to be rescued from the tramway if it fails without cutting the power from the power line. Such installations can be found, for example, south of Zermatt, Switzerland; at the Patscherkofelbahn near Innsbruck, Austria; and at the Penkenbahn in Mayrhofen, Austria.
Read more about this topic: Overhead Line Crossing
Famous quotes containing the word structures:
“The philosopher believes that the value of his philosophy lies in its totality, in its structure: posterity discovers it in the stones with which he built and with which other structures are subsequently built that are frequently better—and so, in the fact that that structure can be demolished and yet still possess value as material.”
—Friedrich Nietzsche (1844–1900)
“If there are people who feel that God wants them to change the structures of society, that is something between them and their God. We must serve him in whatever way we are called. I am called to help the individual; to love each poor person. Not to deal with institutions. I am in no position to judge.”
—Mother Teresa (b. 1910)
“It is clear that all verbal structures with meaning are verbal imitations of that elusive psychological and physiological process known as thought, a process stumbling through emotional entanglements, sudden irrational convictions, involuntary gleams of insight, rationalized prejudices, and blocks of panic and inertia, finally to reach a completely incommunicable intuition.”
—Northrop Frye (b. 1912)