Say Hello To The Floating Trains of the Future

As an inquisitive child growing up, I am mostly fascinated by the small magnet beside my mother's sewing machine. The magnets usually have all types of needles on it. You may agree with me that magnets are fun to play with, but they have many other uses beyond that.

Part of its use is in magnetic levitation (maglev), which finds application in high-speed travel innovation such as high-speed magnetic trains.

^{[Wikipedia Creative Common Image]Source: A maglev train coming out of the Pudong International Airport in Shanghai}

For instance, in 2004, the first commercial high-speed maglev train, Shanghai maglev train, opened up her doors for business and was able to reach a high speed of 431 kilometres per hour or 267 miles per hour. This speed far outstrips the rate of American's Amtrak Train, the fastest high-speed commuter train, which only top speed is 241 kilometres per hour (150 mph).

One of the big challenges of high speed rail transport is the problems of wear and overheating due to friction between rail and bearings.

This challenge is what the maglev train tries to fix. A train that is levitated do not bother about wear or overheating as a result of friction. The only resistance that the train could encounter will be air resistance. This makes the maglev train to move very fast.

The maglev train as we have it today may be something new, but the basic principles of the technology were one that is known for decades dating back to the First World War.

How it works

Maglev trains are mainly about magnetics. From the elementary science, we all know that magnetics comprises of two poles: the north and the south.

^{[Wikipedia Creative Commons]Image by Pieter Kuiper: Magnetic like poles repel}

The like poles (N-N or S-S) repels, and that is the basis of levitation in maglev trains.

The Japenese Rail Pass Company (JR Group) uses this magnetic repulsion to generate lift which lifts the train off the tracks.

Magnet with similar poles is on both the train and the track. This repulsive force creates an invisible, almost magical, cushion which the train rests on.

This method used by the Japanese maglev train engineers are known as the electrodynamic suspension (EDS).

While the Japanese system is based on the repelling force of the magnet, for the German system, the engineers use the magnetic force of attraction (unlike magnetic poles attract). The system is known as the electromagnetic suspension (EMS).

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You can make a homemade electromagnet using either an AA or 9V battery. All that is required is a battery, a copper wire, one nail or screw and a metallic object which you can attract; in this example a small nail.

Wind the copper around the nail, connect one end of the wire to the positive terminal of the battery and the other end to the negative terminal of the cell. You now have an electromagnet that will attract the small nail when the connection is active. Once you disconnect the copper wire from either or both the battery terminals, the magnetism fails. You can watch a video of the process here.

The Germans made use of this principle. But the train will be useless if the track and train attract each other since they will stick together-just like in the homemade experiment above when the copper wires are connected, and the nail was attracted.

The trick was to use the same electromagnetic property to achieve levitation in another style.

The electromagnets attract when current is switched on and loses magnetism when switched off. If you can switch on and off very quickly, the train will be lifted and "dropped" back to the track. But because the switching is high-speed, it will neither drop or attract each other but will hover in the air. That is how the levitation is achieved by the German system of Electromagnetic Suspension (EMS).

Although both the EDS and EMS work on the same principle using magnetism to achieve levitation and propulsion, there are some differences in both features. These differences, advantages and disadvantages are listed in the table below.

Electrodynamic Suspension (EDS)- Japanese System	Electromagnetic Suspension (EMS)- German System
Levitates to about 10cm	Levitates to about 1 cm
Train starts off on rubber wheels before attaining liftoff speed at about 100kph (62 mph)	No wheels here as train lifts off as soon as the guideways are energised
The engineers argue that the wheels are a safety feature too in the event power fails	German engineers said they have emergency battery pack so when power fails the train does not have to drop back on the track at top speed
Faster due to more margin between train and track. Fastest speed recorded is 603km/h or 375 mph	Highest speed recorded is 500 km/h or 310 mph

How Propulsion is Achieved

We have seen how the train achieves its levitation, what is next is how it propels (move) forward.

The alternating magnetic poles is lined up on both side of the tracks of the maglev train with the train moving in between it. The train itself has magnets too on boths sides of it as depicted in the figure above.

The north pole of the track magnet attracts the south pole on the train magnet. On the other hand, the south-pole of the magnet on the track repels the south-pole of the magnet on the train.

The polarity of the magnet on the track changes immediately the attraction and repulsion occur pushing the train forward. Meanwhile, the polarity of the magnet on the train never changes.

The coils in the track create a magnetic field through the pushing and pulling forces which hold the train in position.

An extremely strong magnetic is required to lift and move the train at such high speeds.

For that to occur, a superconducting magnets are made. To make a conductor have extremely low resistance the temperature of it has to be brought down very low. The Linear High-Speed Train has the temperature cooled to -269ºC.

The conventional magnets could barely lift a train 1 cm off the ground. But superconductive magnets are capable of producing the magnetic force capable of speeds of 580km/h in just 8.8 kilometres.

Advantages of Maglev

1. The only friction here is the friction between train and air. The other problems of friction such as overheating, wear and tear are reduced drastically leading to large scale savings in cost.
2. Time of transportation between one point to another is now small. The distance between Tokyo and Osaka is 503 kilometres, conventional Japanese high-speed bullet trains or Shinkansen using the Nozomi(train) will take 2 hours 30 minutes to reach there while travelling at 186 mph or 300km/h. By 2045 the Japenese plan to have a maglev track rail to Osaka to reduce the time to 1 hour while travelling at 500 kilometres per hour or 310 mph.
3. There is reduced CO₂ emission if the source of power is green.

"In addition, the amount of CO2 emissions that the superconducting maglev produces when carrying one person between Tokyo and Osaka is approximately one-third that of airplanes," the company said in a statement. ^Source
4. There is increased safety on use of maglev as it has been proposed to function during an earthquake since it levitates. Building engineers even want to leverage the technology to build homes more resilient to earthquake.

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Everything that has an advantage will have a disadvantage if you look close enough.

Here are some of the disadvantages of the maglev

Disadavtages

1. Cost: The elevated Shanghai Maglev train costs a whopping sum of about $1.58 billion USD for a length of 30.5 kilometres. That translates to a cost per kilometre of the track to be approximately USD 50m which includes the cost of trains and stations.
   In 2008 an Australian Transrapid conventional bullet train costs $34 million AUD for the dual track. That makes the Shanghai Maglev almost twice as expensive as the high-speed train.
2. The magnetic fields from the superconducting magnets may disrupt the workings of a pacemaker. Hence the need to shield passengers with a pacemaker. A pacemaker is a device that helps stimulate and regulate the heart muscle and its contraction. A strong magnetic field could affect its working leading to a fatal result to the wearer.

While we are talking about the high speed of the maglev trains, some are already looking into the future with the vacuum train or vactrain. That is a train that will run in a vacuum. Without air resistance, some believe achieving a speed of 4000 km/hr is possible. The future will be an interesting one for both travel and technology. Can we have such technology or could it be just another pipedream?

Thank you for reading.

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^References

• ^{The Basics of Magnetic Levitated Trains (Maglev)}
• ^{Wikipedia: Maglev}
• ^{Japan's Maglev Trains}
• ^{Long Distance Maglev Plan by Japan}

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