maglev transportation was first proposed more than a century ago,
the first publicly used maglev trains will not debut until at
least next year in Shanghai, China, using the train developed
by a German company. Germany and Japan are both developing maglev
train technology and are currently testing their prototypes.
engineers are building an electromagnetic suspension (EMS) system,
called Transrapid, in which the train's bottom is wrapped around
a steel rail. Electromagnets attached to the train's bottom are
directed up toward the rail, which levitates the train about one-third
of an inch above the rail keep the train levitated even when it's
not moving. Other guidance magnets embedded in the train's body
keep it stable during travel. Germany has demonstrated that the
Transrapid maglev train can reach 300 mph with people onboard.
engineers are developing a competing version of maglev trains
that use an electrodynamic suspension (EDS) system based on the
repelling force of magnets.
Photo ofJapan's MLX01 experimental maglev
key difference between Japanese and German maglev trains is that
the Japanese trains use super-cooled, superconducting electromagnets,
whereas the German's EMS system uses standard electromagnets.
The kind of electromagnet used in the Japanese trains can conduct
electricity even after the power supply has been shut off. By
chilling the coils at frigid temperatures, Japan's system saves
difference between the systems is that the Japanese trains levitate
nearly 4 inches above the rail. One possible drawback in using
the EDS system is that maglev trains must roll on rubber tires
until they reach a liftoff speed of about 62 mph. Japanese engineers
say the wheels are an advantage if a power failure caused a shutdown
of the system. Germany's Transrapid train is equipped with an
emergency battery power supply.
U.S. interest in maglev trains over the past few decades, the
expense of building a maglev transportation system has been discouraging.
Estimated costs for building a maglev train system in the United
States range from $10 million to $30 million per mile. However,
the development of room temperature superconducting supermagnets
could lower the costs of such a system. Room temperature superconductors
would be able to generate equally fast speeds with less energy.
An image of the rail for the Yamanashi maglev test
line in Japan.
An illustration that shows how the guideway works.