Vacuum Tunnel Trains


Vacuum tunnel trains are mainly proposed for a high-speed rail transportation to reduce the travel time of the passengers to the greatest extent. A vactrain (vacuum tube train) is a MagLev (Magnetic Levitation) line that uses evacuated (air-less) or partially evacuated tubes or tunnels. But, vactrains would be intensely expensive without major advances in tunneling and other technology.

Earlier, in the 20th century, The MagLev trains had been a big achievement in Asia all because of its incredible speed and capacity.

The MagLev Technology was invented by Americans Dr.James R. Powell and Gordon T. Danby. Hermann Kemper, Robert Goddard, and Emile Bachelet also been an important part of the research and development that led to this invention. MagLev trains are the vehicles that float on a bed of magnets to cut down friction. These have achieved speeds of up to 581km/h (361mph). But in a vacuum, some believe they could reach speeds of more than 4,000m/h.

Transatlantic passengers often referred the supersonic plane as their “time machine” because of its ability to reach its destination. It took 2 hours to reach London from New York with a speed of 4,000 km/h (2,500 mph).

The history of Vacuum tunnel trains, as they are known, stretches back to more than 100 years in America. Ernst G Frankel, Emeritus Professor of mechanical engineering and ocean engineering from the Massachusetts Institute of Technology said, “Usage of a vacuum tube in the trains permits to achieve high speeds”. It is able to do this because there is little air resistance to slow down the train. Air resistance is a large part of the rolling resistance of a normal train.

Trains moving through the tunnels push the air in advance when the trains start to move and this consumes energy. They also create an area of lower pressure behind them which helps in almost pulling the train back. This air resistance increases dramatically as the trains pick up their speed and friction losses mean that there requires an excess amount of energy to push the train forward against that resistance.


Different designs of the trains have come and many have gone over the years. But the principle behind them is same : “Pump all the air out of a sealed tunnel and then shoot trains, or some sort of transport capsule, through them”. Such ‘evacuated tubes’ could bore through rock, or laid on or above ground like conventional tracks. Some designs also allow them to cross oceans via large-bore pipes tethered at a fixed depth, although these are still more theoretical designs.

Creating a near vacuum in the pipe would allow speeds of up to 930 km/h (580mph) which is twice as fast as in an air-filled tube. The actual plan was to reduce the journey time. For instance, a journey that takes more than four hours has to reduce to just 40 minutes, at a speed of 300 to 350mph (480 to 560km/h).

Prof Frankel explains, “You would have giant pumps keeping a near vacuum in the tube, probably 20 to 30 miles apart (30-40km)”. “The main areas for leaks would be the end stations. The train would pass through a seal as it enters and leaves the tube.”

In fact, the train will have to pass through a series of airlocks that reduce the pressure progressively until the train enters the fully evacuated tunnel, where it could accelerate to high speed.

An American engineer, Daryl Oster, has proposed many configurations and designs from low tech (200mph) systems to high-tech (4,000mph) systems. The low-tech systems for local transport and high-tech systems for continental and intercontinental transport. And it wouldn’t cost much as everyone thought.

Frankel says, “The Vacuum tunnel trains that go from city center to city center could be advantageous.”

Daryl Oster also agrees with him and both believe that they could be using ETT for world travel in less than 10 years, with the most attractive routes between major cities.

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