WASHINGTON - There are only two high-speed magnetic levitation train systems currently in operation, in Germany and Japan, each with differing technologies and features.
The German technology was developed by a company called Transrapid International GmbH & Co., and the Japanese technology is more in the vein of ideas elaborated by James Powell and Gordon Danby, scientists of the U.S. Department of Energy's Brookhaven National Laboratory in the 1960s.
A Florida project, a $600 million, 20-mile system linking Port Canaveral to the Kennedy Space Center and the Space Coast Regional Airport in Titusville, is the only one using Powell and Danby's technology outright.
The Powell-Danby technology uses super-cooled magnets -- to achieve superconductivity -- attached to the vehicle that interact with coils in the track, known as a guideway, that levitate the train by repelling forces.
All the other projects are using the Transrapid technology, which levitates trains based on the concept of attracting magnets.
The Transrapid vehicle wraps around the guideway, with the magnets under the lip section on either side of the guideway. The magnets are attracted to the guideway, drawing the train upward, but the attraction is not so strong that it makes contact.
In the Powell-Danby system, the magnetic forces of the superconducting magnets allow for levitation along a narrow beam, less than four feet wide, which the Florida maglev organizers contend eliminates the costly guideway structures of earlier maglev systems and substitutes a simple, less-obtrusive elevated structure. Coil panels are mounted on the sides of the narrow beam and interact with the vertical magnetic fields of a four-sided superconducting magnet, known as a quadrupole, that provides two magnetic faces, one horizontal and one vertical, which have identical charges at any one time to lift, stabilize, and propel the vehicle.
The Florida project also has a "planar" guideway, where coil panels are mounted horizontally -- forming a flat surface -- that interact with the horizontal field of the quadrupole magnets on the vehicle and allow the vehicle to glide over the flat surface. This eliminates the need for a central beam along the guideway, by substituting the same force for lift, stability, and propulsion.
The planar guideway allows for the ability to exit through a switch, much like exiting an interstate. A train would move into a deceleration lane and get off at the station.
"By virtue of the magnetic forces and the way the coils are laid in this flat surface the planar guideway , the vehicle actually will guide itself over into the deceleration lane and get off at a station, at fairly high speed," said Charles Smith, manager of transportation systems for Maglev 2000 of Florida, a consortium that together with the Florida Department of Transportation hopes to build the maglev train.
The Transrapid design has what is called a bendable switch, where the guideway is bent over to make it fit the off ramp, so to speak. This means that the Transrapid maglev has to slow down to take the ramp, and makes it "not as efficient," Smith contends.
The Powell-Danby system would allow Florida organizers to build off-line stations, or stations that are built on separate pieces of guideway to allow other trains to pass.
"You can program your vehicles to pull off at a station, pick up people; in the meantime, while that vehicle is stopped, another vehicle can go on by," Smith added.
Another difference between these two types of systems is that the cushion of air, the space between the magnet and the guideway, on the Transrapid is about three-eighths of an inch, where as the cushion on the superconducting systems has a six- to eight-inch gap.
"When you build the guideway for the German system, you have to build it very precisely; if you've only got a three-eighths of an inch gap, you can't have very many variations in the guideway, and you have to maintain it at that gap," Smith said.
With the Florida system as well as with the system that the Japanese have built, "the guideway can be built with a little less tolerance ... not to suggest that you can just slap something together," he said. "These things are pretty high-tech stuff and are built very carefully, but the gap does give you a little more leeway."
"Plus in the superconducting system, for which we are proposing to carry container freight, the weight will not have any effect on the gap, where as in the German system there may be a limit to how much weight you can carry without creating some sort of a problem." Smith said.
Smith said benefits of the maglev technology include a cruising speed of more than 240 miles per hour; environmentally friendly characteristics such as low noise, low energy consumption, and minimal land consumption; and low equipment-maintenance costs, since there are few mechanical and moving parts.
