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К истории железнодорожного транспорта. XX век.ОглавлениеRunning off the Rails

Riding on Air in Virginia

Foto of Maglev
A crane hoists American Maglev's magnetically levitated train onto the guideway being built on the campus of Old Dominion University.

First operational magnetic levitation system in United States will carry students across university campus

      TRANSPORTATION. Other magnetically levitated trains may cover many more kilometers and run at much higher speeds, but riders of the one at Old Dominion University (Norfolk, Va.) will have someplace to go at the other end. Instead of being used for test alone, this maglev train will be unique in actually carrying passengers.
      The seminal system, conceived and designed by American Maglev Technology Inc. (Atlanta), is to begin operation on 15 November. It has just one vehicle, which will travel along a single, 1036-meter-long track, suspended by electromagnetic forces on a cushion of air. And its top speed is only 67 km/h, because of the short distance between stations.
      "I thought it was a gadget at first," Robert L. Ash, acting vice president for research at Old Dominion told IEEE Spectrum. "But we realized it could be a lot easier and cheaper to install than any kind of light-rail system we would have considered."

      A little help from some friends. For Old Dominion's vice president of administration and finance, Robert L Fenning, the system was quite a deal. For its price tag of US $14 million, $7 million is coming from private companies, including Lockheed Martin Corp. (Bethesda, Md.), which makes the control system, and Dominion Resources/Virginia Power (Richmond, Va.), the local power company. The other $7 million was loaned by the state of Virginia.
      The money is to be repaid by American Maglev out of future revenue-producing systems using the technology. An early goal is to extend the university's system, if it's successful, by 300 km to Washington, D.C. The vehicle could be modified with relative ease to travel at almost 200 km/h, Tony Morris, president of American Maglev, told Spectrum.
He describes the campus system as akin to a three-stop elevator. Student dorms are at the west end of the line, the academic center is in the middle, and a new basketball pavilion and convocation center is at the east end. The train's low speed is more than adequate for the campus, notes Ash; a roundtrip takes only 7 minutes.
      Data pinpointing the driverless vehicle's location and operation, images from video cameras along the way, and even audio picked up from the train's passengers comes into a central monitoring station. Right now, this is located at the dispatcher's desk of the campus police station. Each trip is controlled from this point.
      The 11000-kg, 16.5-meter-long vehicle [see photograph, left] can carry 100 passengers, who will ride for free. The train glides on a 1.8-meter-wide guideway supported by circular concrete columns, 5-6 meters high. They're placed anywhere from 24 to 27.5 meters apart.
      Ash was surprised by how little students were affected by the line's construction, which took 39 days while classes were in session. "We put up the elevated system so easily," he told Spectrum. "It would have made no sense to tear up our campus to build a light-rail system."

      The guts of the system. The vehicle in American Maglev's system is moved by a pair of 2-meter-long linear induction motors that provide traction in a straight line, rather than rotationally. Each resembles a conventional induction motor but one whose sta-tor with its copper windings has, in effect, been cut open, flattened, and placed, in the vehicle just above the guideway. The equivalent to the motor's rotor - in this case, a flat aluminum "reaction plate" - is placed on the guideway.
      As with a conventional motor, a three-phase voltage applied to the stator produces a traveling electromagnetic field that induces current in the passive reaction plate. This current produces a traveling field of its own, and the two fields interact to create a force strong enough to propel the vehicle.
      DC at 700 V enters the vehicle from a supply rail on the guideway. To control speed, an inverter changes this to a varying frequency ac; a voltage at 100 H, and 200 A, drives the vehicle at its top 67 km/hr speed.
      A set of 12 levitation electromagnets on the vehicle, three at each corner, react with lift reaction sections in the guide-way to suspend the vehicle. Typical clearance between the electromagnets and the guideway is 1 cm. The same lift electromagnets on the vehicle's undercarriage and the guideway keep the vehicle centered. They overcome the effects of the vehicle drifting from side to side because of wind and motion.
      American Maglev's version of the technology relies on the attractive forces of an electromagnetic suspension system that resembles one being developed by Transrapid International GmbH (Berlin). A variant, being pursued by Japan's Railway Technical Research Institute (Tokyo), depends on magnetic repulsion and superconducting magnets. It has reached 552 km/h on a test track in Japan, while the German system has been tested at 450 km/h.
      Privately held, American Maglev was organized in 1994 to develop its version of the technology. It reviewed other systems with Argonne (Illinois) National Laboratory's Technology R&D Center for Transportation, and concluded that it could build a maglev system for $10 - $13 million per kilometer, which is very low compared with costs for light-rail systems. The company owns an 11.3-km test track in Edge-water, Fla., for which it has received funds from the state and county. It has invested more than $10 million on its efforts.
      Old Dominion will not be alone for long in maglev transportation. Three cars for a maglev line arrived in Shanghai in early August following a 40-day sea voyage from Hamburg, Germany. They were built by Transrapid for a 30-km-long line the Chinese government is building to join Shanghai to its Hong Qiao International Airport at speeds of up to 430 km/h. The trip will take about eight minutes, versus 30-40 minutes by taxi.
Alfred Rosenblatt (IEEE Spectrum '02)
К истории железнодорожного транспорта. XX век.ОглавлениеRunning off the Rails