BALTIMORE, DEC. 30 -- A train that would travel 300 miles an hour, pulled above the tracks by magnets, is being studied as a way to carry commuters between Baltimore and Washington.

Two Boston consulting firms plan to deliver a marketing study to the Baltimore-based Abell Foundation in January, said Dan Krechmer of Charles River Associates.

Krechmer said today that his firm was trying to determine whether such a line could draw enough passengers to cover operating expenses.

Akira Yamashita and Associates is studying the technical end of magnetic-levitation trains, said company head Akira Yamashita.

The market research firms were hired in August after the representatives of a Japanese company approached Maryland officials last spring with a proposal to build the train with money raised by private investors at no cost to the state, said a state official.

Magnetic levitation is one of several options being considered by Abell Foundation to tie Baltimore and Washington more closely together, said Robert Embry, foundation president.

Unlike conventional trains, which are powered by diesel or electric locomotives pulling them along the tracks, mag-lev trains are suspended and propelled by electromagnets in the track and under the cars.

The electromagnets "create a traveling magnetic field that pulls the train along," said John Bivens, a vice president of Magnetic Transit of America, an Arizona firm that he said is building a "people mover" in Las Vegas with similar technology.

The train "literally floats on the magnetic field," he said.

The ride is faster and smoother than with a conventional train, and the maintenance and operating costs are lower because the cars are lighter and have fewer moving parts, said Rod Carter, also of Magnetic Transit, which is a U.S. subsidiary of the West German electronics firm AEG-AG.

Despite lower expected operating costs, the cost of building the trains could be as much as $1 billion, said Richard J. Keen, head of the State Railroad Administration.

Keen, who said he is "a little skeptical" about the proposal, based his figure on estimates for a similar project in Florida.

Keen said that a representative of Japan Rail Technical Services met last spring with Maryland Transportation Secretary Richard H. Trainor with a proposal to study the feasibility of building the train.

Keen said the Japanese were confident they could raise the construction money from investors in Japan and the United States, they wanted to make sure they would have the support of the Maryland state government.

No magnetic-levitation trains are in commercial operation, but test tracks have been built in West Germany and Japan.

In addition to the "people mover" in Las Vegas, a commission has been formed in Nevada and California to revive a proposal for a magnetic-levitation train connecting Las Vegas and Southern California that languished from lack of interest.

The 1984 study showed that the project could be built for $2.5 billion but that the private sector and ridership would pay operating costs, said Gus West, of the Las Vegas Department of Economic and Urban Development.