Tracks
Most rapid transit systems use conventional railway tracks and standard gauge, although since tracks in subway tunnels are not exposed to wet weather, they are often fixed to the floor rather than resting on ballast. The rapid transit system in San Diego, California operates tracks on former railroad rights of way that were acquired by the governing entity.
An alternative technology using rubber tires on narrow concrete or steel rollways was pioneered on the Paris Métro, and the first complete system to use it was in Montreal. Additional horizontal wheels are required for guidance, and a conventional track is often provided in case of flat tires and for switching. Advocates of this system note that it is much quieter than conventional steel-wheeled trains, and allows for greater inclines given the increased traction allowed by the rubber tires.
Some cities with steep hills incorporate mountain railway technologies into their metros. The Lyon Metro includes a section of rack (cog) railway, while the Carmelit in Haifa is an underground funicular.
For elevated lines, still another alternative is the monorail. Supported or "straddle" monorails, with a single rail below the train, include the Tokyo Monorail; the Schwebebahn in Wuppertal is a suspended monorail, where the train body hangs below the wheels and rail. Monorails have never gained wide acceptance outside Japan, though Seattle has a short one (in November 2005 voters in Seattle decided against expanding this system, which dates to the World's Fair of 1962), and one has recently been built in Las Vegas. One of the first monorail systems in the United States was installed at Anaheim's Disneyland in 1959 and connects the amusement park to a nearby hotel. Disneyland's builder, animator and filmmaker Walt Disney, offered to build a similar system between Anaheim and Los Angeles.
Read more about this topic: Rapid Transit Technology
Famous quotes containing the word tracks:
“Our law very often reminds one of those outskirts of cities where you cannot for a long time tell how the streets come to wind about in so capricious and serpent-like a manner. At last it strikes you that they grew up, house by house, on the devious tracks of the old green lanes; and if you follow on to the existing fields, you may often find the change half complete.”
—Walter Bagehot (1826–1877)
“I long ago lost a hound, a bay horse, and a turtle-dove, and am still on their trail. Many are the travellers I have spoken concerning them, describing their tracks and what calls they answered to. I have met one or two who had heard the hound, and the tramp of the horse, and even seen the dove disappear behind a cloud, and they seemed as anxious to recover them as if they had lost them themselves.”
—Henry David Thoreau (1817–1862)
“Leonid Ivanovich Shigaev is dead.... The suspension dots, customary in Russian obituaries, must represent the footprints of words that have departed on tiptoe, in reverent single file, leaving their tracks on the marble....”
—Vladimir Nabokov (1899–1977)