Gravity-vacuum transit (GVT) was a form of transportation developed by American inventor Lawrence Edwards in the early 1960s.Scientific American, August 1965: High-Speed Tube Transportation.
Origin
The origin of this technology is
Alfred Ely Beach
Alfred Ely Beach (September 1, 1826 – January 1, 1896) was an American inventor, entrepreneur, publisher, and patent lawyer, born in Springfield, Massachusetts. He is known for his design of the earliest predecessor to the New York City Subwa ...
in 1965. When the
U.S. Department of Defense
The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, t ...
charged all contractors to contemplate what will sustain them if defense funding should taper off, Lockheed Management called for ideas from the troops. Over the long weekend following the assassination of U.S. President
John F. Kennedy
John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), also known as JFK, was the 35th president of the United States, serving from 1961 until his assassination in 1963. He was the first Roman Catholic and youngest person elected p ...
, Edwards sorted through industries and product lines, and focused on
passenger railroad
A passenger train is a train used to transport people along a railroad line, as opposed to a freight train that carries goods. These trains may consist of unpowered passenger railroad cars (also known as coaches or carriages) hauled by one or ...
s, which had lost their former popularity due to the speed of airplanes and the convenience of automobiles. He wondered if trains could travel at airplane speed and converge at city centers rather than at airports 20 miles away.
To avoid high g-forces, high-speed transportation requires nearly straight paths. Shallow tunnels must curve often to avoid the jumble of buildings, subways, and utilities immediately underground. But just a little deeper, near-straight tunnels would be practical, even passing beneath rivers and bays alongside multiple 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
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 a 31-county New York (state), New Yo ...
offered tips and encouragement, visualizing three major suburban lines passing through
Manhattan
Manhattan ( ) is the most densely populated and geographically smallest of the Boroughs of New York City, five boroughs of New York City. Coextensive with New York County, Manhattan is the County statistics of the United States#Smallest, larg ...
, New York. It also published a map for Boston to Washington, D.C., with the Manhattan-to-Washington portion taking only 75 minutes, even with over 10 intermediate stops.Regional Plan News no. 90, September 1969, The Atlantic Seaboard: Development Issues and Strategies.
Specifics
The key to this dramatic performance, validated in peer-reviewed professional papers, is the combined effect of
vacuum
A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...
and
gravity
In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force b ...
. 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 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. Stanford's Dr.
Holt Ashley
Holt Ashley (January 10, 1923May 9, 2006) was an American aeronautical engineer notable for his seminal research on aeroelasticity.
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
Pneumatics (from Greek 'wind, breath') is the use of gas or pressurized air in mechanical systems.
Pneumatic systems used in Industrial sector, industry are commonly powered by compressed air or compressed inert gases. A centrally located a ...
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 engineer, Kearney, in about 1910; he wanted to apply it to
streetcars
A tram (also known as a streetcar or trolley in Canada and the United States) is an urban rail transit in which Rolling stock, vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some ...
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
The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...
Applied Physics Laboratory and others.JHU/APL Technical Memorandum TG-984, May 1968.
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.