Download maglev - Rutgers Physics

Alan Marcus
Maglev Trains
As almost any child knows, magnets have the ability to attract and repel other
magnets. This knowledge is now being utilized in separate projects in Germany and
Japan to propel and levitate a new and innovative type of train, the magnetic lift train.
A German company called Transrapid is now able to build a train takes advantage
of a magnets ability to attract magnetic materials. Upon observing the system from a
distance, it looks to be composed of only T-shaped track and a train that wraps around the
ledges of the track. However, the wrap-around part of the train hides the mechanisms
that cause the train to levitate and to fly through the air. Ferromagnets on the underside
of both of both the track’s ledges attract electromagnets on the wrap-around-the-track
part of the train that is adjacent to the ferromagnets. A computer controls the amount of
current flowing through the electromagnets in order to keep the train at a constant 1 cm
from the track (#5). These electromagnets are powered by onboard batteries that are
charged by linear generators that convert motion into electricity. In addition, the train
needs more than its levitation system to maintain its proper lateral position on the track.
The Transrapid system accomplishes this feat by creating an attractive field between
magnets on both the track’s ledge’s sides and on the interior sides of both the warparound-the-track parts of the train. The two attractive forces cancel each other out and
cause the train to remain in the same lateral distance from the track.(Most of the
information is form #4.)
In addition to levitating the vehicles with magnetic forces, the Transrapid train’s
propulsion system also uses magnetism. The forces used to propel and break the vehicle
are both created with the aluminum three-phase cable winding in the ferromagnets on the
track and the electromagnets on the train. The train moves forward when an alternating
current, supplied by an outside source, is sent through the windings on the track. This
creates an alternating magnetic field that both pushes and pulls the train along the track.
In order to slow the train down the alternating current is reversed. This causes the train to
be pushed and pulled in the direction opposite of its motion. Also, this system is energy
efficient because instead of electrifying the entire track, the only electrified part is length
where the train is traveling. (This paragraph is brought to you by #4)
The Transrapid technology has many excellent qualities that would make it an
attractive transportation option for customers. The trains are extremely safe to ride
because the train’s wrap-around-the-track design makes it virtually impossible to derail.
Also, the German design is safe for all passengers because it produces an electric field
close to Earth’s own electric field. Therefore, people with pace makers could use these
trains. Passenger would also enjoy the smooth ride that Transrapid provides when it is
not accelerating. In addition, the passengers would appreciate the high speeds that these
vehicles can achieve because of the lack of friction between the track and the train. The
Transrapid design can accelerate to 200 mph in 3 miles, and can whisk passengers at
speeds up to 300 mph. The high acceleration will delight passengers with minute travels
times for short hops, and the high overall speed allows the train to cover distances of up
to 500 miles in the same time it takes an airplane when travel time to the airport and
check in time are considered. (This paragraph is also form #4.)
Besides passengers, businesses and governments would also find Transrapid
appetizing. Initially, a company will not have to spend any more to install this magnetic
lift system than any other type of train system. A magnetic train would cost around $20
to $40 million per mile to construct, but 17 years ago the building of the I-279 in
Pittsburg consumed $37 million for every mile of track laid down(#2). Once the system
is constructed, the maintenance costs will be trivial because the train’s parts will not
touch each other and therefore there will be no wear or tear(#4). Its lack of maintenance
and its efficient system of electrifying only the part of the track in use translates into an
operational expenses that are half that of other trains(#4). In addition, these trains could
carry a large quantity of people because each train section holds about 100 seats and each
train is composed of two to ten segments(#4).
For people who want to preserve the environment, Transrapid systems would be
an appealing option. First, Transrapid uses one third of the energy that cars use per
person per mile and one fifth of the energy that jets use per person per mile. Therefore,
depending on the fuel source, using less energy would reduce the amount of carbon
dioxide, sulfur dioxide and nitrogen oxides released into the air. Also, the Transrapid
tracks would have less environmental impact. The elevated models, which are 50 feet in
the air, would allow animals of all sizes to pass beneath them safely, and the low models,
which are five to ten feet in the air, would allow small animals to pass under them safely.
In addition, since the magnetic lift trains can mold to the landscape better their tracks
would not alter the environment as much as the tracks of regular trains. The need for
tunnels would be reduced because Transrapid trains can climb 10%gradients, whereas
normal trains can only climb 4% gradients. In addition, these new German trains would
not pollute the surrounding area with a high level of noise despite their high velocities
because the propulsion system parts do not touch one another. The amount of noise
produced by a passing maglev train would be analogous to the amount of sound made by
city traffic.(#4)
Transrapid’s success is like a tide, it crests and then it eddies. China has hired
Transrapid to build a 20 mile test route between Shanghai Pudong and Pudong
International Airport. The system will be operating in January of 2004, and if it is
successful then China will connect Beijing and Shanghai, a journey of over 800 miles,
with a maglev train(#4). In addition, the United States Congress said it is planning to
spend $1 billion dollars on a Transrapid project between either Pittsburgh’s suburbs and
its airport or between Washington International Airport and Baltimore. However, the
money has not been appropriated yet(#2). Transrapid met with complete failure in its
own home nation when the government cancelled a project between Berlin and Hamburg.
The authorities decided that the improvement of the transportation between the two cities
over the existing ICE trains is not enough to warrant spending $7 billion dollars.(#2)
Besides the German Transrapid, the Japanese are building a maglev system called
Chuo Shinkansen. Though the German and the Japanese system are similar there are
some key differences between the two technologies. The basic set up of the Japanese
system is different because it uses a U-shaped track and the onboard magnets are
superconducting magnets that are cooled by liquid helium or liquid nitrogen(#1). The
advantage to using superconducting magnets is that once electrified, they stay electrified
if they are maintained at a low enough temperature.
The Japanese levitation system also differs from the Transrapid one. A current is
conducted in figure eight levitation coils on the side of the track as the superconducting
magnets pass by them. This induced current creates a magnetic field that repels the
superconducting magnets on the train and thereby levitate it 10 cm above the track. This
system has drawbacks because in order to induce a current in the coils the train needs to
pass by the coils at a speed of 50 mph. To fix this problem, the Chuo Shinkansen has
retractable wheels that support it until it can become airborne. In addition, the Japanese
version has a lateral guidance system that is similar to the Transrapid one. As the train’s
lateral position shifts the superconducting magnets induces a current in the figure eight
coils on the side of the track. The lateral position is adjusted because the magnetic field
on the side closer to the train repels the car, and the magnetic field on the farther side
attracts the car. (This paragraph came form #3)
The Transrapid and Chuo Shinkansen propulsion systems are quite similar. It is
propelled by sending an alternating current through electromagnets that are placed in the
interior sides of the U-shaped track. The alternating current creates a magnetic field that
pushes and pulls the train forward. In order to break, the current is simply reversed, and
this slows the train down by pushing and pulling it in the opposite direction. (This
paragraph is from #3)
The Japanese technology, even though it will not be ready to use for a couple of
years, has many advantages associated with it that supports its implementation when the
technology is ready. One bonus is the high velocities, up to 350 mph when people are
aboard, that can be achieved because the friction between the car and the track is lowered
to zero(#3). Another advantage, which is important to a land that is situated on a fault, is
that the large amount of space, 10 centimeters, between the track and the train makes the
system earthquake proof. It is earthquake proof because the large amount separation
leaves more room for deformations to occur (#4).
However, despite the advantages of the Chuo Shinkansen, the Japanese public is
not solidly behind implementing the technology. One drawback is that the construction
of a maglev train system will carry a hefty price tag (#2). The other negative aspect is the
high magnetic field that the superconducting magnets produces. This field would cause
problems for passengers with pace makers and for passengers who want to talk on cell
phones(#4).
Hence, both Maglev technologies are safe, efficient and speedy modes of
transportation that may be implemented in many areas in the near future. However, these
new trains face the major obstacle of convincing governments that they are worth the
money when trains already run similar routes.
Bibliography
#1: http://www.howstuffworks.com/maglev-train.htm
This is a howstuffworks.com page that describes how magnetic lift trains work.
#2: http://www.post-gazette.com/regionstate/20010128maglevtechsidereg9.asp
This site from post-gazette.com that discusses how interest in maglev trains has been up
and down.
#3: http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html
This site discusses how the Japanese maglev train works.
#4: http://www.transrapid.de/en/index.html
This is the Transrapid international website.
#5:http://news.nationalgeographic.com/news/2001/12/1219_wiremagtrains.htmlernationa
l site.
This is a National Geographic article that deals with how maglev trains work and how
they are being accepted.