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Magnetic attraction: High speed trains

By Peter N. SpottsStaff writer of The Christian Science Monitor / December 13, 2001



After a few minutes playing with toy magnets, even a child quickly sees that one magnet can push or pull the other around.

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But it took a rocket scientist at the turn of the past century to make the conceptual leap of using magnetic attraction and repulsion to replace the thunder of locomotives with the whoosh of trains that rarely touch track. Instead of clacking along steel rails, trains would ride on a cushion of magnetic fields at speeds of up to 300 miles an hour, propelled by manipulating the magnets' attraction and repulsion.

Now, nearly a century after Americans Robert Goddard and Emile Bachelet conceived of magnetic-levitation trains, maglev is beginning to move from the test track to the main line. In China, the United States, and Germany, plans - and, in one case, guideways - are being laid for modest systems that backers hope will demonstrate the technology's potential to unclog airports and highways.

"It's a technology whose time has come," says Christopher Brady, president of Transrapid International USA Inc. in Washington, D.C. Transrapid USA's German parent company is building a system in China, and is said to have the inside track on several projects in the US.

Research on maglev trains has been under way for decades, with Japan, Germany, and the United States spending abaout $1.5 billion each on maglev R&D. But while government-funded research ended in the US in 1975, the other two players pushed ahead.

American maglev activity received a boost, however, in the omnibus transportation bill Congress passed three years ago. Among other provisions, the bill set up ground rules for a competition that will lead to the first substantial maglev demonstration line in the US.

Last January, US Transportation Secretary Rodney Slater selected two finalists from seven competing projects.

Pittsburgh plans to run a 47-mile line connecting the city to its airport and eastern suburbs, while Baltimore plans a 40-mile stretch of guideway from Camden Yard to Union Station in Washington via the Baltimore-Washington International Airport.

The winner garners $950 million in federal grants to help pay for construction.

Last week, Transportation Secretary Norman Mineta made additional money available to Los Angeles and Las Vegas, which didn't make the final cut, to continue studies on their proposals. Atlanta, another sidelined competitor in the federal program, is pressing ahead on studies of a line to Chattanooga on its own.

Meanwhile, the US Senate's version of an economic-stimulus package contains a $7-billion bond program to fund expansion of high-speed rail, including the introduction of innovative technologies such as maglev trains.

Fresh orange juice with your maglev?

One of the most influential states in advancing or retarding maglev trains could well be Florida. While all eyes focused on the outcome of the presidential race in Florida last year, voters overwhelmingly backed an amendment to the state Constitution that gives state officials two years to begin construction of a statewide high-speed rail system that links the state's five largest urban areas.

One of the issues planners must decide is whether they will opt for a maglev system or a conventional high-speed rail system, such as France's TGV or Amtrak's new Acela.

Currently, maglev trains fall under two basic designs, notes Don Rote, a retired physicist who worked on maglev development at the Argonne National Laboratory in Argonne, Ill.

The Germans' approach, embodied in Transrapid's design, uses magnetic attraction to levitate and propel a train. The train's wheel-free undercarriage wraps around a T-shaped guide edged with thin metal "guidance rails."

Computers and sensors control support and guidance magnets on the undercarriage that keep the train within three-eights of an inch of its guide rail on each side and about six inches above the guideway.

The underside of the guideway also contains windings that, when electrified with alternating current, generate their own set of magnetic fields, which continuously attract the support magnets.

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