A TRAIN with NO WHEELS

EVEN before boarding the gleaming new streamlined train in Shanghai, China, passengers sense that they are traveling on a railway with a difference. That feeling is heightened as the train whispers away from its ultramodern station and accelerates rap­idly and smoothly to more than 430 kilo­meters an hour, making it the fastest com­mercial railway on earth. It completes the 3û-kilometer journey to Pudong Internation­al Airport in just eight minutes. But there is something particularly special about this train-it has no wheels!

The Shanghai-Pudong line boasts the world's only commercial magnetic levitation,

or maglev, railway. Rather than riding on met­al wheels, the train is supported entirely by a magnetic field. And instead of having a hu­man driver, it is fitted with technology that constantly monitors its exact position and radios the data to a central control station. There, human operators, aided by computers, precisely control the train's movements.

Maglev Versus Conventional Railways

The construction of this special train and its guideway posed a number of challenges. For instance, only a narrow air space sep­arates the moving train from its guideway. Hence, because of Shanghai's soft soil, en­gineers had to include special joints in the guideway that can be adjusted to compen­sate for natural settling. They also had to keep in mind the slight deformation that concrete beams experience, including temperature-related expansion and contraction.

Still, maglev technology offers a number of advantages. For instance, it produces no mo­tor or wheel noise and no harmful exhaust emissions from the vehicle itself. Track and equipment need less maintenance. And as a mode of passenger transport, the energy ef­ficiency of the train is about three times that of an auto and five times that of an air­plane. I n fact, the energy the train uses to hover is less than that consumed by its air-conditioning system! Additionally, the train can climb steeper slopes and handle tighter curves than its wheeled counterpart, thus re­ducing the need to alter the landscape.

With all these advantages, it might seem surprising that more maglev railways have not been built. One factor is the greater ini­tial cost. Indeed, Chinese officials have put on hold a proposal to build a maglev line between Shanghai and Beijing because con­struction would cost twice that of a normal high-speed line. Also, a maglev line would not be integrated with China's existing rail net­work.

The Shanghai maglev railway uses German technology, and maglev research continues in Germany, Japan, and elsewhere. In Decem­ber 2003, Japan's developmental maglev train set a world rail speed record of 581 kilome­ters an hour. For now, the train in Shanghai remains unique as a commercial enterprise.

As the maglev leaves Pudong on its return trip to Shanghai, the eyes of the passengers are glued to the digital speedometers locat­ed in each car, keen to see when they indi­cate top speed. Indeed, on their first ride, many passengers miss much of the scenery, so they make a second trip. Watching the terrain flash by, they fully understand why the maglev has been called a "plane without wings."