Vactrain
From Wikipedia, the free encyclopedia
A vactrain is an exotic, as-yet-unbuilt proposal for future high-speed railroad transportation. This would entail building maglev lines through evacuated (air-less) tunnels. Though the technology is currently being investigated for development of regional networks, advocates have suggested establishing vactrains for transcontinental routes to form a global subway network. The lack of air resistance can permit vactrains to move at extremely high speeds, up to 6000-8000 km/h (4000-5000 mph or Mach 5-6), according to the Discovery Channel's Extreme Engineering program Transatlantic tunnel.
Theoretically, vactrain tunnels could be built deep enough to pass under oceans, thus permitting very rapid intercontinental travel. Vactrains could also use gravity to assist their acceleration. If such trains went as fast as predicted, the trip between London and New York would take less than an hour, effectively supplanting aircraft as the world's fastest mode of public transportation.
Without major advances in tunnelling and other technology, however, vactrains would be prohibitively expensive. Alternatives such as elevated concrete tubes with partial vacuums have been proposed to reduce costs.
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[edit] History
As far back as the late 19th century, proposals were made for a non-evacuated transatlantic tunnel linking the United States and Great Britain. This idea was highlighted in the 1933 German film Der Tunnel, remade as the 1935 British film Transatlantic Tunnel.
The modern concept of a vactrain, with evacuated tubes and maglev technology, was pioneered in the 1910s by American engineer Robert Goddard, who designed detailed prototypes while a university student. His train would have travelled from Boston to New York in 12 minutes, averaging 1000 mph. The train designs were found only after Goddard's death in 1945.
Vactrains made headlines during the 1970s when a leading advocate, Robert F. Salter of RAND, published a series of elaborate engineering articles in 1972 and again in 1978.
An interview with Robert Salter appeared in the LA TIMES (June 11, 1972). It discussed, in detail, the relative ease with which the U.S. government could build a tube shuttle system using technologies available at that time. Salter also pointed out how such a system would help reduce the environmental damage being done to the atmosphere by aviation and surface transportation. Robert Salter called underground Very High Speed Transportation (tube shuttles) our nation's "logical next step." Sadly (and most probably due to the economic effects on the airline industry), the plans were never taken to the next stage. (Some researchers, however, such as Richard Sauder, John Rhodes, Bill Hamilton and TAL, have contended that a nation wide tube-shuttle network has been built by the U.S. military to assure Continuity Of Government [COG] operations during or after a major war on U.S. soil).
At the time these reports were published, national prestige was an issue as Japan had been operating its showcase bullet train for several years and maglev train research was hot technology. The American Planetran would establish trans-planetary subway service in the United States and provide a commute from Los Angeles to New York City in one hour. The tunnel would be buried to a depth of several hundred feet in solid rock formations. Construction would make use of lasers to ensure aligment and use tungsten probes to melt through igneous rock formations. The tunnel would maintain a partial vacuum to minimize drag. A trip would average 3000 mph and subject passengers with forces up to 1.4 times that of gravity, requiring the use of gimballed compartments. Enormous construction costs (estimated as high as US$1 trillion) were the primary reason why Salter's proposal was never built.
Recent vactrain proposals by Frank Davidson, a founding member of the Channel Tunnel project, and Japanese engineer Yoshihiro Kyonati have tackled the transoceanic problems by floating a tube above the ocean floor, anchored with cables. The transit tube would remain at least 100 feet below the ocean surface to avoid water turbulence. The same method is already in use in the Transbay Tube.
[edit] Popular culture
Vactrains have occasionally appeared in science fiction, including in the works of Arthur C. Clarke (Rescue Party, 1946), Peter F Hamilton (The Night's Dawn Trilogy), Joe Haldeman (in his novel Buying Time), Larry Niven (A World Out of Time), and Jerry Yulsman (Elleander Morning). The Space 1999 TV series, featured a Lunar Vactrain. A similar transportation system is mentioned in the technologically utopian song "I.G.Y.," on Donald Fagen's 1982 album The Nightfly:
- At this point in time... it's clear
- The future looks bright
- On that train all graphite and glitter
- Undersea by rail
- Ninety minutes from New York to Paris....
