Whllever happened 10 mallev?Bui flu matter Wh:OII approach the

researchers have taken, maglev systemsrequire complex and costly track along theentire distance ticvsled. The additionalcost is a significant drawback whenmaglev is compared with air travel.

Overcoming aerodynamic drag at highspeeds has been a major problem. In addi­tion, magnetic drag of about 3 percent at480krrJhmeans considerable energy mustbe consumed to 11ft the vehicle.

To reach superconductivity. or zero elec­trical dc resistance, the magnets must bekept very cold (4.2 K).· Therefore, temp­erature regulation and cryostat mainten­ance are very significant problems.

Although no adverse biological effectshave been observed from human exposureto constant magnetic fields, magneticfields in the passenger compartmentsmust be reduced because of their effect onany metal a passenger might be carrying.Conventional means of reducing thesefields require large cross sections of iron,w1iich can make the vehicle heavy.

Further problems in the way of commer­cial exploitation of the vehicle are posed byhigh speed. Long distances between stopsare necessary to allow for acceleration anddeceleration. As a result, right-of-way per­mits without local access by way of a sta­tion could be tied up in the courts for years.

Safety and reliability are major con­cerns. As L Fletcher Prouty, an author andconsultant on railroad technology, put it:"At such speeds, hitting a pigeon couldcause a major explosion." Again, manyconventional solutions can increase thevehicle's weight significantly.

During the Ford administration, all high­speed ground-transportation research wascut. At that time, maglev research efforts,inclUding all levitation techniques andwork on the linear induction motor,werestopped. Among those dropped was a two­year, $2 million contract on a repulsionsystem with the Ford ~.1otOi Co. Robert H.Borcherts, a research scientist there,recalled: "The aluminum for the guidewaywas already purchased. We were sixmonths into the project when the contractwas canceled. We put five or six years ofwork into mag lev at Ford, but now we donothing."

One iaason the u.s. halted Its research,Mr. Prouty said, is that it "concentrated onthe air-cushion technique, and this wasnever a workable system." The air-cushionlevitation technique, predecessor of the at­traction and repulsion techniques, has

Promising fast, quiet, smooth, energy­efficient transportation, "maglev"-theusa of super-conducting magnets tolevitate and propei vehicies-has been apopular goal of researchers since the late1esos. Naw maglev vehicles expected tospeed at up to 500kilometers per hourwereenvisioned as overcornlng many of theproblems of conventional transportation.Academic and lnduatrtal researchersaround the world embarked on majormaglev projects and suggested that com­mercial systems could be In operation bythe early-to-mid-1980s.

These predictions have yet to be borneout, but magiev is stlll considered a promis­Ing alternative to conventional transporta­tion by countries other than the UnitedStates. Government-sponsored researchcontinues In Japan, West Germany, Bri­tain, and Canada. The U.S. government,however, has stopped funding researchbecause of the large capital Investmentneeded to overcomeproblems such as con­structing the long distances of tracknecessary for a commercially usefulsystem.

~.1aglev vehicles are propelled by a travel­Ing magnetic field created when the elec­tromagnets on the vehicie interact with alinear motor winding along the guideway.Alternating current fed into the guidewaychanges the direction of the magneticwave with the motion of the vehicle, so thatthe magnets on the vehicle are attracted tothe guideway ahead and repened frombehind. To stop the vehicle, the polarity isreversed.

The degree of levitation using magneticattraction and repulsion varies. With theattraction approach, electromagnets onthe vehicle are drawn to a steel rail, leav·Ing about a 1-centimeter gap betweenthe vehicle and the rail. In systems basedon magnetic repulsion, the vehicle re­pels the aluminum track, leaving a muchlarger gap.

Maglev systems concepts date to theturn of the century. In 1911 a Swissengineer, Benjamin Graeninger,- first pro­posed the electromagnetic principle forsupporting a mass under a ferromagneticrail. A year later Emile Bachelet con­structed the flrst experimental vehicle us-­Ing that principle. In the 193Cs HermannKcm!'l8r in Germany tested electromag­netic levitation models and developed cir­cuitry to control the levitation. The idea lay~rmant for nearly 30 years after that. Thenin 1966, two scientists from theBrookhaven National Laboratories in NewYork State-James R. Powell, a nuclearengineer, and Gordon R. Danby, a physi­cist-proposed superconductivity formaglev systems. This inspired subsequentresearch In the U.S., Japan, Canada, WestGermany, and Britain.

The U.S. Federal Railroad Administra­tion sponsored studies by the StanfordResearch Institute, Palo Alto, Calif., theFord Motor Co.,and the AiResearch Manu­facturing Co.,Torrance, Calif. The NationalSCience Foundation funded projects at theMassachusetts Institute of Technology'sFrancis Bitter Magnet Laboratory and atthe Raytheon Co., Lexington, Mass.

IEEE spectrum AUGUST 1982

Maglev venictes arelifted, guided, and pro­pelled by forces ofmagnetic attractionand repulsion. Elec­tromagnets on thetrain interact with thetrack; vertical forceslift and horizontalforces propel andguide. In attractionsystems, the rail at­tracts the vehicle's liftmagnets upward.

GUIDANCEA:!.4!:NET

since been abandoned in all research ef­forts. Because it was an older technology,more time and money were Invested In It.

Apparently many other governments didnot agree with the U.S.,for maglev researchIs still alive and strong elsewhere. TheJapanese are by far the most advanced,with the government seriously committedto the effort. The Japanese NationalRai!~"!:lYshas reported successfully achiev­Ing speeds of 530krn/h with an experimen­tal repulsion system planned to !Inkmajorpopulation centers, and efforts are nowfocused on increasing speed. JapanAirlines stopped work a few years ago onan attraction system to carry passengersbetween the center of Tokyo and the air­port, but it has recently revived the programand joined with West Germany in a three­year effort to perfect an attraction system.

SCientists in West Germany. financiallyaided by the government. tiave demon­strated the success of both repulsion andattraction systems. At the InternationalTransport Exhibition in Hamburg in 1979,the Thyssen Henschel company of Kassel,West Germany, operated a completemaglev system with traffic control andmon Itorlng.

in Britain, construction of an attractionsystem has begun at Birmingham Airport.The project, a joint venture of severalBritish industries and the British depart­ments of trade and industry, Is expected tobegin operation in June 1984. It will travelbetween Birmingham'S National exhibitioncenter and the airport terminal building in9().second runs.

Canada, where the government hasspent a total of about $1 million on maglevresearch, is not as seriously committed asJapan and West Germany. The CanadianInstitute of Guided Ground Transport hascroposed a repulsion system that wouldrun the Toronto-Ottowa-Montreal corridorat 450 kmlh.

At Brookhaven National laboratories onLong Island, Dr. Powell does not anticipatefurther Federal involvement at this time Inany high-speed transportation research.Without such a commitment by the Gov­ernment, he said, private groups will not beable to raise the money necessary to finish!h~ !"~s~arch.

"The Germans and Japanese have astronger view of the government role intransportation," acec=-d!:1a to Dr. Powell."They have more of a commitment to masstransportation and trains. The U.S. Is morecommitted to cars."

VEHICLE

GUIDEWAY

17