Gravity-Vacuum Transit
Encyclopedia
Gravity-Vacuum Transit was a form of transportation developed by American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 inventor Lawrence Edwards
Lawrence Edwards
Lawrence K. Edwards is an accomplished American innovator in aerospace and ground transportation. Early in his career, he pioneered cutting-edge technologies for U.S. space and missile defense programs. He went on to invent and promote high-speed Gravity-Vacuum Transit and monobeam rail transit...

 in the early 1960s.

Origin

The origin of this technology is Alfred Ely Beach
Alfred Ely Beach
Alfred Ely Beach was an American inventor, publisher and patent lawyer, born in Springfield, Massachusetts.-Early years:Beach was born in Springfield, Massachusetts and was the son of a prominent publisher, Moses Beach...

 in 1865. When the U.S. Department of Defense charged all contractors to contemplate what will sustain them if defense funding should taper off, Lockheed
Lockheed Corporation
The Lockheed Corporation was an American aerospace company. Lockheed was founded in 1912 and later merged with Martin Marietta to form Lockheed Martin in 1995.-Origins:...

 Management called for ideas from the troops. Over the long weekend following the assassination of U.S. President John F. Kennedy
John F. Kennedy
John Fitzgerald "Jack" Kennedy , often referred to by his initials JFK, was the 35th President of the United States, serving from 1961 until his assassination in 1963....

, Edwards sorted through industries and product lines, and focused on passenger railroads, which had lost their former popularity due to the speed of airplanes and the convenience of automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

s. He wondered if trains could travel at airplane speed and converge at city centers rather than at airports 20 miles away.

Clearly, such speed demands a nearly straight path, avoiding the jumble of city streets and buildings, and even the subways
Rapid transit
A rapid transit, underground, subway, elevated railway, metro or metropolitan railway system is an electric passenger railway in an urban area with a high capacity and frequency, and grade separation from other traffic. Rapid transit systems are typically located either in underground tunnels or on...

 and utilities immediately underground. But just a little deeper, near-straight tunnels would be practical, even passing beneath rivers and bays alongside many major cities. This pointed to a design with each tunnel enclosing a pair of steel tubes for two-way traffic, each tube having been pumped out until the air pressure is below that experienced by modern passenger planes.

Drawing on the wisdom of technologists and urban planners, as well as lengthy visits to major libraries, Edwards progressively synthesized his system wherein trains nearly ten feet in diameter and with 500 - 1500 passengers would speed up to 250 mph (urban) and 400 mph (regional) through the tubes, protected from the weather and other hazards. The Regional Plan Association
Regional Plan Association
The Regional Plan Association is an independent, not-for-profit regional planning organization, founded in 1922, that focuses on recommendations to improve the quality of life and economic competitiveness of the 31-county New York-New Jersey-Connecticut region...

 offered tips and encouragement, visualizing three major suburban lines passing through Manhattan
Manhattan
Manhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...

, New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

. It also published a map for Boston
Boston
Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...

 to Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, with the Manhattan-to-Washington portion taking only 75 minutes, even with over 10 intermediate stops.

Specifics

The key to this dramatic performance, validated in peer-reviewed professional papers, is the combined effect of vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

 and gravity. Leaving a station with full atmospheric pressure behind it but near-vacuum ahead, the train is subject to 75 tons of thrust, far exceeding what a locomotive can do at moderate speeds. Approaching the next station, the train is decelerated by a similar pressure differential, but in reverse. Passengers experience swift but acceptable acceleration/ deceleration, provided designers are careful not to make the steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 cars too light.

There is no propulsive equipment on the train at all; instead, there are massive(but commercial-scale) vacuum pumps steadily pulling air out of the tubes and exhausting it outdoors. And their task is eased by the fact that the amount of air admitted to the tube to accelerate a train is only a little more than that pushed back into the atmosphere as the vehicle comes to a stop. The pumps make up the difference, and can do that while running at a constant rate. And when a GVT train rises to the same elevation it had at the start, it recovers the gravity component of the down-slope energy at a delightful 100% efficiency. Stanford's Dr. Holt Ashley, while a national science executive in 1974, asked about GVT and stated that it was "the most energy-efficient form of transportation we ever saw."

Unique features

GVT has a powerful advantage not shared by airplanes or any form of transit that moves horizontally. Rolling down a moderate slope, for example 20%, there is robust acceleration that the passengers "don't feel at all". This can be superimposed on the pneumatic acceleration discussed above. Then with the maximum tunnel depth limited to about 1000 feet, gravity alone can add 100 mph to the train's speed at the midpoint of a three-mile segment, for an elapsed time of 1.5 minutes stop-to-stop without exceeding customary passenger-comfort limits. The essential feature of this phenomenon was recognized by a British
British people
The British are citizens of the United Kingdom, of the Isle of Man, any of the Channel Islands, or of any of the British overseas territories, and their descendants...

 engineer, Kearney, in about 1910; he wanted to apply it to streetcars but couldn't convince his peers and it was forgotten." Edwards read of it in the New York public library, adapted it for vastly higher speeds, and improvised ways to convince the skeptics.

This unique feature was further validated in a contract study by Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...

Applied Physics Laboratory and others.

End of the line

Further study and lab tests of GVT were suggested, but these were not funded, and were a casualty of a general cutback in Federal funding for most forms of advanced rail transit in 1969. Edwards' company, Tube Transit Inc., closed its doors and he went on to pursue an aerial transit system, Project 21 Monobeam, which was first conceived as a local system to feed passengers to GVT.
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