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INDEX

S. No. CONTENTS PAGE No.

1. Introduction 4

2. History 5

3. Theory of operation 10

4. The functioning of maglev 14

5. Technology behind the maglev trains 16

6. Benefits of EMS-attractive and EDS-repulsive Systems 20

7. Prototype 21

8. Final track and circuit 23

9. Advantages and disadvantages of maglev 25

10. Maglev v/s conventional train 26

11. Comparison with aircraft 28

12. Safety 28

13. Accidents 29

14. Future scope and expansions 32

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LIST OF FIGURES

S. NO. DESCRIPTION PAGE NO.

1 VIRMINGHAN INTERNATIONAL MEGLEV SHUTTLE

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2 JNR ML 500 AT MIYA ZAKI JAPAN 8

3 MAGNITIC FIELD OF PERMANENT MAGNET &ELECTRO MAGNET & THEIR RESULTANT FORCE

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4 DIAGRAM EXPLANING THE DIFFERENT TYPE OF MAGNETISM

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5 MODEL OF DIAMAGNETIC MATERIAL REPELLING THE MAGNET

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6 ELECTROMAGNETIC SUSPENSION 17

7 PROPULSION OF MAGLEV 18

8 MAGLEV TRACK 19

9 PROTOTYPE OF TRACK 21

10 CIRCUIT USED IN PROTOTYPE 22

11 FINAL TRACK DESIGN 23

12 FRONT VIEW OF TRAIN 25

13 FINAL CIRCUIT 24

14 MEN TRYING TO EXTINGUISH THE FIRE IN SHANGHAI TRANSRAPID

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15 THE ACCIDENT SITE 30

16 THE COLLISION WITH THE MAINTENANCE VEHICLE

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17 WATER BEING SPRAYED TO DOUSE THE FIRE

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ABSTRACT

The goal of this project was to build a model maglev train. The train would be propelled by a linear motor system and would be levitated by a diamagnetic material over a magnetic track. The linear motor was built, but due to time and budget constraints, the levitation system was not added. Overall, the train was very powerful - achieving an acceleration of roughly 5.4 m/s/s, but it was highly inefficient - achieving an efficiency of roughly 9%. To make the train more efficient in the future, superconducting electromagnets should be used on the train so that a high current could be obtained without losing energy to heat dissipation. The train and track were built so that in the future, a levitation system could possibly be added. Though powerful, the train and track were highly expensive to build, and more cost-effective technology would be necessary to make maglev trains feasible. Maglev system represents a promising evolution in the high speed ground transportation, offering speeds in excess of 500 mph along with the potential for low operating costs and minimal environmental impact. The goal of this effort is to investigate the feasibility and viability of maglev systems in Japan.

The idea for this project came from a Scientific American article that described proposed maglev systems around the world and their potential for future travel. The goal of this project was to gain a better understanding of maglev trains, as well as to see their advantages in speed and efficiency and disadvantages in cost and design.

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INTRODUCTION

High-speed rail has proved to be a very practical source of long-distance transportation. The first high-speed train line opened in Japan in 1964 connecting Tokyo and Osaka, traveling at speeds up to 200 km/h. Current high speed rail technology can achieve speeds of about 270-350 km/h making it comparable to air travel in terms of speed over short distances of about 700 km. In fact, trips on high-speed rail are often shorter than trips by plane, because rail trips are not delayed by weather. More importantly, high-speed rail is an environmental friendly mode of transportation, using only a fraction of the energy that planes and cars use, and using clean electricity instead of fossil fuels as its source of energy. Yet despite the huge success high-speed trains have achieved throughout the world, researchers are still trying to develop new technologies that would make rail travel even faster and more efficient.

Maglev trains have been the technology of interest that researchers have been looking into. They were first proposed in the 1960s by two physicists at Brookhaven NationalLaboratory, whose vision, led to huge research projects in Japan and Germany. Since then, maglev test tracks have been built in countries all around the world, and the first commercially operating maglev train opened in Shanghai in 2004.

Maglev is defined as a “family of technologies in which a vehicle is suspended, guided, and propelled by means of magnetic forces”. Generally, magnets and electromagnets are oriented so that the train levitates off the track just enough to avoid friction contact. This same magnetic system or another one is also used to propel and guide the train.

The major advantage of maglev trains is speed (up to 580 km/h [3]), which increases the range in which rail travel is comparable to air travel. Other advantages include incredible efficiency, since levitation eliminates all friction that is normally created by rails; reduced noise pollution, again due to reduced friction; and faster acceleration, which further improves the travel time. The major disadvantage, which has been the primary reason for a lack of maglev projects throughout the world, is cost, because unlike with conventional high-speed rail, completely new infrastructure must be built. The cost for this can total up to $100 billion.

This project was chosen to investigate maglev trains. The design for this maglev train was not based on any current maglev technology, nor does it seek to improve on any current technology. Rather, the purpose of this project was to build a working model of a maglev train so that the principals behind magnetic levitation and propulsion can be better understood. Efficiency and power were also factors that were investigated over the course of this project. Though the efficiency and power of the train built in this project were not improved upon after building the model, possible improvements were brainstormed, and they are discussed later in this paper.

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HISTORY

FIRST PATENT

High-speed transportation patents were granted to various inventors throughout the world. Early United States patents for a linear motor propelled train were awarded to the inventor, Alfred Zehden (German). The inventor was awarded U.S. Patent 782,312 (14 February 1905) and U.S. Patent RE12, 700 (21 August 1907). In 1907, another early electromagnetic transportation system was developed by F. S. Smith. A series of German patents for magnetic levitation trains propelled by linear motors were awarded to Hermann Kemper between 1937 and 1941. An early modern type of maglev train was described in U.S. Patent 3,158,765, Magnetic system of transportation, by G. R. Polgreen (25 August 1959). The first use of "maglev" in a United States patent was in "Magnetic levitation guidance system" by Canadian Patents and Development Limited.

DEVELOPMENT

In the late 1940s, Professor Eric Laithwaite of Imperial College in London developed the first full-size working model of the linear induction motor. He became professor of heavy electrical engineering at Imperial College in 1964, where he continued his successful development of the linear motor. As the linear motor does not require physical contact between the vehicle and guideway, it became a common fixture on many advanced transportation systems being developed in the 1960s and 70s. Laithwaite himself joined development of one such project, the Tracked Hovercraft, although funding for this project was cancelled in 1973.

The linear motor was naturally suited to use with maglev systems as well. In the early 1970s, Laithwaite discovered a new arrangement of magnets, magnetic river that allowed a single linear motor to produce both lift as well as forward thrust allowing a maglev system to be built with a single set of magnets. Working at the British Rail Research Division in Derby, along with teams at several civil engineering firms, the "traverse-flux" system was developed into a working system.

The first commercial maglev people mover was simply called "MAGLEV" and officially opened in 1984 near Birmingham, England. It operated on an elevated 600-metre (2,000 ft) section of monorail track between Birmingham International Airport and Birmingham International railway station, running at speeds up to 42 km/h (26 mph); the system was eventually closed in 1995 due to reliability problems.

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NEW YORK, UNITED STATES 1968

In 1950, when he was delayed during rush hour traffic on the Throgs Neck Bridge, James Powell, a researcher at Brookhaven National Laboratory (BNL), thought of using magnetically levitated transportation to solve the traffic problem.[14] Powell and BNL colleague Gordon Danby jointly worked out a Maglev concept using static magnets mounted on a moving vehicle to induce electrodynamic lifting and stabilizing forces in specially shaped loops on a guideway.

HAMBURG, GERMANY 1979

Transrapid 05 was the first maglev train with longstator propulsion licensed for passenger transportation. In 1979, a 908 m track was opened in Hamburg for the first International Transportation Exhibition (IVA 79). There was so much interest that operations had to be extended three months after the exhibition finished, having carried more than 50,000 passengers. It was reassembled in Kassel in 1980.

BIRMINGHAM, UNITED KINGDOM 1984–1995

The world's first commercial automated maglev system was a low-speed maglev shuttle that ran from the airport terminal of Birmingham International Airport to the nearby Birmingham International railway station between1984–1995. The length of the track was 600 metres (2,000 ft), and trains "flew" at an altitude of 15 millimeters (0.59 in), levitated by electromagnets, and propelled with linear induction motors. It was in operation for nearly eleven years, but obsolescence problems with the electronic systems made it unreliable in its later years. One of the original cars is now on display at Railworld in Peterborough, together with the RTV31 hover train vehicle.

Fig. 1 Birmingham International Maglev shuttle

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Several favorable conditions existed when the link was built:

The British Rail Research vehicle was 3 tonnes and extension to the 8 tonne vehicle was easy.

Electrical power was easily available. The airport and rail buildings were suitable for terminal platforms. Only one crossing over a public road was required and no steep gradients were involved. Land was owned by the railway or airport. Local industries and councils were supportive. Some government finance was provided and because of sharing work, the cost per

organization was low.

After the original system closed in 1995, the original guide way lay dormant. The guide way was reused in 2003 when the replacement cable-hauled Air Rail Link Cable Liner people mover was opened.

JAPAN 1985

In Japan, there are two independently developed maglev trains. One is HSST by Japan Airlines and the other, which is more well-known, is JR-Maglev by Japan Railways Group.

The development of the latter started in 1969, and Miyazaki test track had regularly hit 517 km/h (321 mph) by 1979 but, after an accident that destroyed the train, a new design was decided upon. In Okazaki, Japan (1987), the JR-Maglev took a test ride at the Okazaki exhibition. Tests through the 1980s continued in Miyazaki before transferring a far larger and elaborate test track, 20 km (12 mi) long, in Yamanashi in 1997.

Fig.2 JNR ML500 at Miyazaki, Japan test track on 21 December 1979 517 km/h (321 mph)

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Development of HSST started in 1974, based on technologies introduced from Germany. In Tsukuba, Japan (1985), the HSST-03 (Linimo) wins popularity in spite of being 30 km/h (19mph) at the Tsukuba World Exposition. In Saitama, Japan (1988), the HSST-04-1 was revealed at the Saitama exhibition performed in Kumagaya. Its fastest recorded speed was 30 km/h (19 mph).

VANCOUVER CANADA AND HAMBURG GERMANY 1986–1988

In Vancouver, Canada (1986), the JR-Maglev was exhibited at Expo 86. Guests could ride the train along a short section of track at the fairgrounds. In Hamburg, Germany (1988), the TR-07 in international traffic exhibition (IVA88) performed Hamburg which was also in 1988.

Berlin, Germany 1989–1991

In West Berlin, the M-Bahn was built in the late 1980s. It was a driverless maglev system with a 1.6 km (0.99 mi) track connecting three stations. Testing in passenger traffic started in August 1989, and regular operation started in July 1991. Although the line largely followed a new elevated alignment, it terminated at the U-Bahn station Gleisdreieck, where it took over a platform that was then no longer in use; it was from a line that formerly ran to East Berlin. After the fall of the Berlin Wall, plans were set in motion to reconnect this line (today's U2). Deconstruction of the M-Bahn line began only two months after regular service began that was called Pundai project and was completed in February 1992.

HISTORY OF MAGLEV SPEED RECORDS

1971 – West Germany – Prinzipfahrzeug – 90 km/h (56 mph) 1971 – West Germany – TR-02 (TSST) – 164 km/h (102 mph) 1972 – Japan – ML100 – 60 km/h (37 mph) – (manned) 1973 – West Germany – TR04 – 250 km/h (160 mph) (manned) 1974 – West Germany – EET-01 – 230 km/h (140 mph) (unmanned) 1975 – West Germany – Komet – 401 km/h (249 mph) (by steam rocket propulsion,

unmanned) 1978 – Japan – HSST-01 – 308 km/h (191 mph) (by supporting rockets propulsion, made

in Nissan, unmanned) 1978 – Japan – HSST-02 – 110 km/h (68 mph) (manned) 1979-12-12 – Japan-ML-500R – 504 km/h (313 mph) (unmanned) It succeeds in

operation over 500 km/h for the first time in the world.

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1979-12-21 – Japan – ML-500R – 517 km/h (321 mph) (unmanned) 1987 – West Germany – TR-06 – 406 km/h (252 mph) (manned) 1987 – Japan – MLU001 – 401 km/h (249 mph) (manned) 1988 – West Germany – TR-06 – 413 km/h (257 mph) (manned) 1989 – West Germany – TR-07 – 436 km/h (271 mph) (manned) 1993 – Germany – TR-07 – 450 km/h (280 mph) (manned) 1994 – Japan – MLU002N – 431 km/h (268 mph) (unmanned) 1997 – Japan – MLX01 – 531 km/h (330 mph) (manned) 1997 – Japan – MLX01 – 550 km/h (340 mph) (unmanned) 1999 – Japan – MLX01 – 548 km/h (341 mph) (unmanned) 1999 – Japan – MLX01 – 552 km/h (343 mph) (manned/five formation). Guinness

authorization. 2003 – China – Transrapid SMT (built in Germany) – 501 km/h (311 mph)

(manned/three formation) 2003 – Japan – MLX01 – 581 km/h (361 mph) (manned/three formation). Guinness

authorization.

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MAGNETIC LEVITATION

The principle of magnetic levitation is that a vehicle can be suspended and propelled on a guidance track made with magnets. The vehicle on top of the track may be propelled with the help of a linear induction motor. Although the vehicle does not use steel wheels on a steel rail they are still referred to as trains as by definition they are a long chain of vehicles which travel in the same direction. This is the definition of a MAGLEV train.

THEORY OF OPERATION

The propulsion system used is known as a linear motor. Unlike a conventional motor, a linear motor creates linear motion instead of circular motion. As mentioned above, the major principle behind its operation is magnetic repulsion. Permanent magnets on the rails directly next to the electromagnets (figure 1) exert a magnetic field Bp1. Electromagnets also exerts a magnetic field Be. Bc can be approximated as follows (the actual equation is slightly more complicated, but this equation is just used to show that Be is roughly proportional to the current):

Be=µ0nI Where n is the number of coils, and I is the current.

The direction of these magnetic fields can be seen in figure 1a. Since these magnetic fields are opposing each other, there is a repulsive force, which pushes the electromagnet away. The electromagnet experiences two repulsive forces, one from the electromagnet on one rail, and one from the other rail. As can be seen in the figure, the direction of these repulsive forces is away from their respective permanent magnets, and since the two permanent magnets are opposite of each other, in theory, the two repulsive forces would cancel each other out, and the net force would zero. However, there is an extremely low probability that the electromagnet is lined up exactly with the permanent magnets. If the electromagnet is even the slightest bit off center - for example, if the electromagnet is further down than center (see figure 1b), the force from the left permanent magnet will have a right and a down component, while the force from the right permanent magnet will have a left and down component. Though the left and right components cancel each other out by symmetry, there is still a net down component, giving the electromagnet, and therefore the train, a net acceleration downwards.

The electromagnet, initially when the train is started will in all probability not be perfectly lined up, so there will be a net force downwards. Also, if the train has some velocity, the train will have enough inertia to move to this point where it will feel the net force downwards, and will thus continue to move even faster downwards. Furthermore, the train will be in the magnetic field Bp2 - which is the field due to the set of permanent magnets directly below the first set - and as seen in figure 1c, the fields are pointing in the same direction, so there is an attractive force downwards (and by the same symmetry arguments used above, the train is also accelerated downwards by this set of forces as well).

When the train moves to the next set of magnets - the ones that it is attracted to – there will be an attractive force that resists motion. However, a sensor in the circuit senses the change in magnetic field, which sends a signal that causes the current to reverse .Thus the magnetic field of

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the electromagnet is in the opposite direction, the attractive force becomes a repulsive force, and the propulsion cycle continues.

Since magnets - both the permanent ones and the electromagnets - are dipoles, it is very difficult to calculate the exact force experienced by the cart. Furthermore, many of the components, especially the permanent magnets are not laid out perfectly on the track, which would cause any such calculations to only be an approximation. However, it is shown in the equation above that Be is proportional to the current going through the electromagnet, and it can be assumed that when Be increases, the forces of repulsion/attraction due to the permanent magnets also increases (most likely Be ~ F). Thus the force experienced by the train is roughly proportional to the current going through the electromagnet. Current can be calculated using Ohm’s law (I = ΔV/R, where ΔV is the potential difference across the power source and R is the resistance of the electromagnet).

Figure 3: Magnetic fields of the permanent magnet and electromagnets and the resultant force. 1a) When magnets and electromagnet perfectly lined up, the repulsion forces on the electromagnet oppose each other and cancel each other out. 1b) With a slight perturbation, the sideways component of the forces will cancel each other out, but the downwards components add to create a net force downwards. 1c) The attractive forces downward caused by the next magnets in the series also result in a net downwards force, making the downwards pull even stronger.

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Figure 4: Diagrams explaining the different types of magnetism. Ferromagnetic materials are permanent magnets, diamagnetic materials are repelled when put in a magnetic field, and paramagnetic materials are attracted when put in a magnetic field.

Linear motors have one key advantage that make them much more powerful than conventional motor/engine based propulsion systems: they don’t rely on friction. In cars, for example, to convert rotational motion into linear motion, there must be friction between the wheels and the ground so that the wheels can push the car forward. Yet friction also reduces the efficiency of the car because as the car moves, work is done by friction, generating heat and reducing the kinetic energy of the car. With a linear propulsion system, friction is not required to propel the vehicle because magnetic attraction and repulsion does the job. So in fact, the friction between the vehicle and the ground could in fact be zero, which would give the vehicle an incredible efficiency. If the vehicle was to levitate off of the ground, there would be no friction, and the only force the vehicle would be combating would be air resistance. This is in fact what Maglev trains do - they levitate off of the ground in order to achieve almost zero friction.To create levitation, a magnetic repulsion force is used to counteract the force of gravity. The right magnetic material must be used to achieve levitation. Magnetic materials are classified into three categories: paramagnetic, diamagnetic, and ferromagnetic (see figure 4).

Paramagnetic materials are materials that, when placed in a magnetic field, experience an attractive force towards the source of the field. In a paramagnetic material, the atoms, which are magnetic dipoles, are able to rotate and orient themselves in the direction of the permanent magnet. The result is a net magnetic field produced by the material in the same direction as the permanent field, resulting in an attractive force.

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Figure 5: Model of a diamagnetic material repelling a magnet.

The diamagnetic material is the disk in the center. A changing magnetic field induces a current in the material that opposes the magnetic field. In this example, current flows clockwise. Due to the fringing magnetic field from the permanent magnet, there is a field component on the same plane as the current flow. By the right hand rule, a force is felt perpendicular to the plane of current and field. In this example, this force is up. In all cases, the force will be pointing away from the magnet. (This can be shown using deduction analogous to this). Thus a diamagnetic material will always repel a permanent magnet or any type of net magnetic dipole.

Diamagnetic materials essentially are opposite to paramagnetic materials - if placed in a permanent magnetic field, they will experience a repulsion force. When the material experiences a change in magnetic field, a current is induced in the material. According to Lenz’s law, the magnetic field induced must oppose the direction of the other magnetic field (see figure 5). Since current interacting with a perpendicular magnetic field produces a net force perpendicular to both of them, the fringing magnetic field interacts with the current to produce a net force away from the magnet (see figure 5 to see an explanation with vectors). Thus the diamagnetic material is repelled from the source of the magnetic field. Diamagnetic materials are the rarest of the magnetic materials, because for a material to be truly diamagnetic, the material should

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experience repulsion even when the magnetic field that it is inside is not changing. In most circumstances, this would require the current to continue flowing, even when no current is being induced on the material. This requires very low resistance. Because of this, superconductors – or materials with an electrical resistance of effectively zero - are the most effective diamagnetic materials. Non-superconducting diamagnetic materials are more practical (since superconductors are rare and require supercooling to acquire superconductivity), but because they do not have superconductivity, their diamagnetism is weaker.

Ferromagnetic materials are essentially permanent magnets. In these materials, quantum effects cause the “spin” (which is what causes a magnetic moment) of the electrons to always be oriented so that there is a net magnetic dipole. Thus these materials always produce a magnetic field. It would seem that magnetic levitation could be simply achieved by taking two permanent magnets (ferromagnets), or a combination of them, and orienting them so that they repelled each other. However, magnetic levitation is much more complicated than that. It was proved in 1842 by a scientist named Samuel Earnshaw that it is impossible to create any sort of stable levitation using stable “charges” that relies on any classical inverse square force. In terms of magnetism, Earnshaw’s theorem states that it is impossible to stably levitate a permanent magnet using other permanent magnets. However, this does not imply that magnetic levitation is impossible. If non-ferromagnetic materials are used to levitate a permanent magnet, the assumption of the theorem is false and therefore the theorem does not hold up. Obviously, paramagnetic materials cannot be used to create levitation, because levitation relies on a repulsive force, while paramagnetic materials only undergo an attractive force. Diamagnetic materials on the other hand can be used. The diamagnetic material repels all of the magnetic field lines it encounters. Thus, if a diamagnetic material is placed above a magnet, the sideways component of the repulsion force is exactly zero by symmetry. Thus only a net force upwards is felt, resulting in levitation.

THE FUNCTIONING OF MAGLEV

Some would say that maglev is the biggest breakthrough in ground transportation since the invention of the wheel. Ironically, this distinction was achieved precisely by eliminating wheel-on- rail, or wheel-on-roadway modes of transport. Without friction, without moving parts which have to be lubricated and tended to, the operational side of vehicle maintenance is greatly reduced.

But what exactly does it mean to travel without a wheel? For example, what then drives the maglev, since the normal tractive power of a locomotive, a car engine, or the horse that pulls the wagon is now eliminated. Without the normal tractive power, what makes maglev go?

Most children who have played with magnets, which should include everyone, have noticed that north pole attracts south pole. If a north pole-oriented and a south pole-oriented magnet are put close to one another, they will pull together so tightly, depending on the strength of the magnet, that it will take some effort to pull them apart. By contrast, one cannot force two magnets of the same polarity-- north-north, south-south-- to touch one another, no matter how hard one pushes.

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Electromagnets, depending on the number of winds in the coils, and strength of the current, can be made many times stronger than the strongest natural magnet. One can set a magnetic force with a south pole-orientation immediately in front of a magnetic force with a north-pole orientation, and cause attraction. If the north- pole oriented magnetic force is anchored to a vehicle, and the force of attraction to the south-pole oriented magnetic force is strong enough, the magnetic force will tug or pull the entire vehicle forward. This is the principal of propulsion in an attractive-EMS maglev system. But in order for this to work, two other conditions must be in place. First, the vehicle must already be elevated, or floating. This too can be achieved through magnetic attraction. So, in an Electromagnetic Suspension (EMS) - positive attraction system, electromagnetic force is used for both the functions of propulsion and levitation, although a different series of magnets is dedicated to each function. Electromagnetic force is also used for a third function: guidance-- keeping the train on the magnetic track, giving it tilt, or pitch and roll when necessary, etc.

The second key condition that must be met for maglev, is that one can turn the current on and off very rapidly, and at will. Thus one can create a magnetically oriented north pole, and withdraw it back to neutral, as in the case of EMS-attractive system propulsion; or one can create a magnetically oriented north pole, and then by changing the direction of the current, create an opposite south pole polarity, in the place where one had a north pole only a fraction of a second ago, as in the case of EDS- repulsive system propulsion. Electromagnetism, as opposed to normal magnetism, allows one to do this, by turning on and off, or shifting directionality of the current. What happens is that the frequency of action is so great, that one doesn't end up with many discrete steps, but rather a process that is apparently continuous: one creates a standing electromagnetic wave.

We will look at the propulsion and levitation principles, at least schematically of the two dominant maglev systems: EMS- attraction and EDS-repulsion. Though there may be many variants of each system, all maglev research for commercial purposes is focusing on one or the other system.

However, this raises a frequently asked question: where is the motor or engine in the maglev system? The answer that there is none is not strictly accurate: there is a motor, it's just not where one would normally think to look for it. The motor of a maglev system is the interaction between the electromagnets/superconducting magnets (SCMs) and the guide way; the package of the two, and their interaction is what constitutes the motor. Otherwise, there is no standing motor aboard, as in the case of train locomotive or automobile engine.

In a normal conventional motor, say an induction motor, there are two principal parts: the stator, which is the outer circle, which is stationary, and consists of a series of windings, called the primary windings; and the rotor, which is the inner circle, which can rotate as a result of action from the stator, and which consists of a series of windings called secondary windings. The rotor is most frequently connected to a shaft which can rotate, performing work. What happens is that a magnetic force in the primary windings of the stator induces a voltage, which induces a current in the secondary windings of the rotor. The total process causes the rotor to rotate (often, in this system, the polarity of the poles of the stator are alternated very rapidly between north, south, north, etc).

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There are other motors, for example, synchronous motors. But whatever the motor, in a maglev system, it is linearized, meaning that it is opened up, unwound, and stretched out, for as long as the track extends. Usually, the straightened stators, whether they be long or short, are embedded in the track, and the rotors are embedded in the electromagnetic system onboard the vehicle; but on occasion, in some systems, the roles can be reversed. This becomes important in the propulsion system.

Technology behind the maglev trains

The term "maglev" refers not only to the vehicles, but to the railway system as well, specifically designed for magnetic levitation and propulsion. All operational implementations of maglev technology have had minimal overlap with wheeled train technology and have not been compatible with conventional rail tracks. Because they cannot share existing infrastructure, these maglev systems must be designed as complete transportation systems. The Applied Levitation SPM maglev system is inter-operable with steel rail tracks and would permit maglev vehicles and conventional trains to operate at the same time on the same right of way. MAN in Germany also designed a maglev system that worked with conventional rails, but it was never fully developed.

There are two particularly notable types of maglev technology:

For electromagnetic suspension (EMS), electronically controlled electromagnets in the train attract it to a magnetically conductive (usually steel) track.

Electrodynamic suspension (EDS) uses superconducting electromagnets or strong permanent magnets which create a magnetic field that induces currents in nearby metallic conductors when there is relative movement which pushes and pulls the train towards the designed levitation position on the guide way.

Another experimental technology, which was designed, proven mathematically, peer reviewed, and patented, but is yet to be built, is the magnetodynamic suspension (MDS), which uses the attractive magnetic force of a permanent magnet array near a steel track to lift the train and hold it in place. Other technologies such as repulsive permanent magnets and superconducting magnets have seen some research.

Electromagnetic suspension

In current electromagnetic suspension (EMS) systems, the train levitates above a steel rail while electromagnets, attached to the train, are oriented toward the rail from below. The system is typically arranged on a series of C-shaped arms, with the upper portion of the arm attached to the

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vehicle, and the lower inside edge containing the magnets. The rail is situated between the upper and lower edges.

Fig.6 Electromagnetic suspension

Magnetic attraction varies inversely with the cube of distance, so minor changes in distance between the magnets and the rail produce greatly varying forces. These changes in force are dynamically unstable – if there is a slight divergence from the optimum position, the tendency will be to exacerbate this, and complex systems of feedback control are required to maintain a train at a constant distance from the track, (approximately 15 millimeters (0.59 in).

The major advantage to suspended maglev systems is that they work at all speeds, unlike electrodynamic systems which only work at a minimum speed of about 30 km/h (19 mph). This eliminates the need for a separate low-speed suspension system, and can simplify the track layout as a result. On the downside, the dynamic instability of the system demands high tolerances of the track, which can offset, or eliminate this advantage. Laithwaite, highly skeptical of the concept, was concerned that in order to make a track with the required tolerances, the gap between the magnets and rail would have to be increased to the point where the magnets would be unreasonably large. In practice, this problem was addressed through increased performance of the feedback systems, which allow the system to run with close tolerances.

PROPULSION

In the attractive-EMS system, electromagnetic attraction is also used to power the train vehicle forward, but it uses a electromagnetic system dedicated for propulsion and separate from the electromagnetic system used for levitation. For propulsion purposes, there are ferromagnetic

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stator packets (with three-phase mobile field windings) attached to the guideway. When activated, they attract the electromagnet onboard the maglev. A three-phase current, of varying frequency, is used, and generated through different stators in different segments of the track. The stators that are excited are always just in front of the maglev vehicle. As the stators are excited sequentially, the electromagnets onboard 'chase' the current forward along the track, providing forward motion, or propulsion.

The EMS-attractive system maglev surfs with its support magnets on the alternating magnetic field generated in the roadway. The created electromagnetic wave is actually a mobile or travelling electromagnetic wave. The EMS-attractive system is sometimes labeled a "pull" system: the vehicle is pulled forward.

Braking is done by reversing the magnetic field. Some trains also have air flaps, like airplanes, to slow down, as well as wheels that extend downward or outward to the guide way for emergency braking in the unlikely event that everything else fails.

The propulsion of the EDS-repulsive system can be described as "pull- then neutral- then push." (EDS-repulsive also usually uses a linear synchronous motor or a locally commutated motor). In the EDS system, coils or an aluminum sheet in the guide way are used for providing drive, although they also are different than the coils dedicated for the function of levitation.

Fig.7 Propulsion of maglev

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The coils in the guide way are excited by an alternating, three-phase current. This produces an alternating magnetic field, or standing magnetic wave. As with EMS- attraction, sections of the guide way are excited sequentially, with the excited section being immediately in front of the maglev vehicle. Superconducting magnets onboard the maglev vehicle are attracted to the section of the guide way immediately ahead of it, pulling the vehicle forward. Then, when the vehicle is directly overhead, the direction of the current (and thus the polarity) of the particular guide way segment is changed. During the fraction of a section in which the polarity is being changed, there is effectively neither an attractive nor repulsive interaction. But once the change in polarity occurs, and while the front of the vehicle is moving forward to the next excited portion of the guide way, a repulsive force is created, pushing the vehicle from behind. This occurs-- the vehicle's movement-- in coherence with the alternating magnetic field.

So, if the EMS-attractive drive system is a "pull system," the EDS-repulsive drive system is a "pull-neutral-then push system."

MAGLEV Track

The track along which the train moves is called the guide way. Both the guide way as well as the train’s undercarriage also have magnets which repel each other. Thus the train is said to levitate about 0.39 inches on top of the guide way. After the levitation is complete, enough power has to be produced so as to move the train through the guide way. This power is given to the coils within the guide way, which in turn produces magnetic fields, which pulls and pushes the train through the guide way.

Fig.8 (MAGLEV Track)

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The current that is given to the electric coils of the guide way will be alternating in nature. Thus the polarity of the coils will be changing in period. Thus the change causes a pull force for the train in the front and to add to this force, the magnetic field behind the train adds more forward thrust.

BENEFITS OF EMS-ATTRACTIVE AND EDS-REPULSIVE SYSTEMS

There are different benefits to the EMS-attractive and the EDS-repulsive system. The EMS-attractive system has had more testing, and appears more ready to go. It also does not require a secondary suspension system, which the EDS-repulsive system does.

But there are two features of the EDS system, which make it very attractive and promising. First, the EDS-repulsive system employs superconducting magnets (SCMs), which for a variety of reasons, the EMS-attractive system cannot. The benefits are potentially large, and it will also mean development in the field of SCMs. In 1908, Kamerlingh Onnes, working at the University of Leiden in Holland, succeeded in liquefying helium by achieving a temperature of only 4.2 degrees Kelvin (or above absolute zero) for the first time.

In 1911, Onnes discovered the phenomenon of superconductivity, while exploring how far the electrical resistivity of a pure metal would decrease as the temperature dropped. He found that some materials brought down to 4.2L Kelvin exhibited virtually no resistance to an electrical current-- the current once established, continued to flow unimpeded and appeared to be capable of persisting forever: no resistance means no loss of energy through heat dissipation. It has been estimated that superconducting magnets for maglev will only have to be recharged after about 400 hours of use, or every 2 weeks, if the vehicle ran continually. By contrast, electromagnets of the EMS-attractive system require a continuous input of current to create the magnetic fields.

The importance of the discovery can be illustrated by the fact that a conventional 12 gauge copper wire cannot carry a current greater than 20 amperes because resistive energy loss and heating would melt the copper; a comparable wire of a superconducting alloy, such as niobium-titanium, can carry a current of 50,000 amperes, if kept at the temperature of liquid helium. Superconductivity is an immense benefit to maglev in terms of reducing power requirements: once the power is introduced into the system at the beginning of the ride, it stays, without loss, for the whole ride, cutting down hugely on the power requirement per passenger-mile travelled.

A second advantage of EDS-maglev is that it has a larger air gap than EMS-maglev, meaning that the system should handle wind- gusts, or hilly terrain, or earthquakes, or other disturbances, much more smoothly. It is also believed, that hypothetically, EDS- maglev will be able to attain higher speeds in the long-run.

However, whichever system of maglev one chooses, it is light- years above all other existing conventional modes of ground transport. According to a Rand Corporation study, referred to earlier in this pamphlet, a second generation maglev system that travels in an evacuated tunnel-- i.e., a vacuum, could potentially travel the 2,800 miles between New York City and Los Angeles

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in less than an hour. No ground-based form of transport, and no commercial airplane can do that, or will be able to for some time to come.

Prototype

A diagram for the prototype track and propulsion system can be seen in figure 7 . The track used a linear motor propulsion system as described in the theory section. Magnets were placed so that there were alternating pairs of magnets. There were two walls with magnets so the train would have a symmetrical force on both sides. A plastic rail was used to guide the train. Originally, a levitation prototype was also to be built, but due to time and budget constraints, this did not happen. Figure 8 is a diagram of the circuit used to drive the train. The electromagnets were hooked up to a relay that would reverse the direction of the current when switched. The relay was triggered by a hall-effect sensor hooked up to a transistor. When the train moved from one set of permanent magnets to another, the hall-effect sensor sent a signal to the transistor, which switched the relay. This caused the current to reverse, which, as mentioned in the theory section, changed the direction of the magnetic field in the electromagnet, allowing the train to continue repelling the permanent magnets and allowing the train to keep moving.

Prototype Track

Figure 9: Prototype of track.

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This diagram only shows the propulsion system. The levitation system was not implemented. A wheeled train (not shown) was used on this track. Blue disks represent magnets with north Pole facing forward, red disks represent magnets with south pole facing forward. Two electromagnets will be placed on the train which (controlled by the circuit) will change the direction of current so that they will always repel the permanent magnets they are in front of, causing propulsion.UPDATE: On the first prototype, like poles were positioned directly across from each other on the two rails. This was modified so that opposite poles are across from each other (as seen in the picture, e.g. south poles are across from north poles). This was so that a single electromagnet for the positioning of the electromagnet could be used to get a repulsive force from both rails at the same time, instead of one side being attracted to the rails and the other side being repelled

PROTOTYPE CIRCUIT:

Figure 10: Circuit used in prototype.

A hall chip (HC) sends a signal to the transistor with a sensed change in magnetic field that causes current to either flow or cease to flow in the transistor. This current is sent through a relay, which, when switched, reverses the direction of current in the output. The output is to be sent to two electromagnets in parallel that were built for the prototype (one of which is roughly 50Ω, one of which is roughly 10Ω), which will be placed on either side of the train. UPDATE:

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The 15Ω resistor that was originally attached to the relay’s switch was removed to give more power to the electromagnets.

Final Track and Circuit

This design was modeled after the prototype design, except it was roughly tripled in size. Track was made out of HPDE plastic, and instead of using pre-made external rails, the plastic was shaped so there would be rails built onto the track. There are a total of 48 holes on each side for the magnets (not shown). The magnets used were 1/2” diameter neodymium magnets, spaced 0.75” apart and oriented in the same way as on the prototype (every other one alternating). Both sides of the track are symmetrical, but with the magnets oriented in opposite directions, like on the prototype. The same wheeled cart was used with a similar circuit.

Figure 11: Final track design.Similar to the prototype, with minor changes, smaller resistors were used in conjunction with the hall-effect chip circuit (the 8.3KΩ and the 16Ω resistors) so that the chip would be able to switch

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the relay even if less than 9.0V was fed through it. Also, the LED’s were taken out of the circuit because the current running through the circuit caused them to burn out. The output voltage was hooked up to two roughly 12Ω electromagnets, for a total resistance of about 6Ω.

Figure 12: The final circuit.

Final Design

The final track built was based off the prototype track. Due to time constraints, a levitation system was not added. This would have required additional research and testing that could have required a few months to complete. Originally, a circular track was to be built, but due to budget constraints, a smaller track design was needed. A long, straight track was chosen as the final design, similar to the prototype design. The design was made flexible so that in future projects, a levitation system could be added and the track could be expanded.

The track was made out of HPDE plastic. This material was chosen because it is sturdy and durable, yet easy to cut and mold. It also has a low coefficient of friction against the wheels of the car used, allowing for little energy to be lost to friction. The magnetic propulsion system was the exact same as in the prototype system - with 1/4” magnets alternating in polarity every other magnet. The two rails with magnets were placed at the optimum position so that would be as close as possible to the electromagnets without being attracted to the iron core of the electromagnets. This allowed for the maximum repulsion force.

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The circuit used on the final design (figure 9) was the same as on the prototype, with only a few minor tweaks (see description of figure 9). The only major change was using electromagnets with lower resistance. Though this increased the power dissipated by the electromagnets in the form of heat, it increased their strength which allowed for greater acceleration (see results section for more discussion on this).

RESULTS

The following is a specification sheet for the final track.

mass 0.375 kgDimensions Shown in fig.3Operating voltage 9VAverage current 1.56 ± 0.03 APower input 14 ± 0.3 WAverage acceleration (with9.00V input voltage)

5.4 m/s2 ± 0.3 m/s2

Average power output (with9.00V input voltage)

1.3W ± 0.1W

Table 1

ADVANTAGES OF MAGLEV

The main advantage is maintenance. There is no contact between the guide way and the train which lessens the number of moving parts. Thus the components that wear out is little.

Another advantage is the reduction in noise. As there are no wheels running along there is no wheel noise. However noise due to air disturbance will still be there.

The next advantage is high speed. As there are no frictional contacts, the train is prone to have more speed.

Another advantage is that the guide way can be made a lot thicker in uphill places, after stations and so on. This will help in increasing the speed of the train further.

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DISADVANTAGES OF MAGLEV

The initial cost of MAGLEV trains is highly costly. The guide paths are also supposed to be more costly than conventional steel railways.

ENVIRONMENTAL FRIENDLINESS OF MAGLEV TRAINS

MAGLEV trains are more environmentally friendly than other types of trains.  In terms of energy consumption maglev trains are slightly better off than conventional trains. As there is no wheel friction with the ground, the resistive force gradually increases in the air friction. Thus the energy efficiency difference between a MAGLEV train and a conventional train is of very small margin.

MAGLEV v/s Conventional Train

Maglev transport is non-contact, electric powered. It does not rely on the wheels, bearings and axles common to mechanical friction-reliant rail systems.

Speeds Maglev allows higher top speeds than conventional rail, but at least experimentally, wheel-based high-speed trains have been able to demonstrate similar speeds.

Maintenance Requirements Of Electronic Versus Mechanical Systems: Maglev trains currently in operation have demonstrated the need for nearly insignificant guide way maintenance. Their electronic vehicle maintenance is minimal and more closely aligned with aircraft maintenance schedules based on hours of operation, rather than on speed or distance traveled. Traditional rail is subject to the wear and tear of miles of friction on mechanical systems and increases exponentially with speed, unlike maglev systems. The running costs difference is a cost advantage of maglev over rail and also directly affects system reliability, availability and sustainability.

All-Weather Operations: While maglev trains currently in operation are not stopped, slowed, or have their schedules affected by snow, ice, severe cold, rain or high winds, they have not been operated in the wide range of conditions that traditional friction-based rail systems have operated. Maglev vehicles accelerate and decelerate faster than mechanical systems regardless of the slickness of the guide way or the slope of the grade because they are non-contact systems.

Backwards Compatibility: Maglev trains currently in operation are not compatible with conventional track, and therefore require all new infrastructures for their entire route, but this is not a negative if high levels of reliability and low operational costs are the goal. By contrast conventional high speed trains such as the TGV are able to run at reduced speeds on existing rail infrastructure, thus reducing expenditure where new infrastructure would be particularly expensive (such as the final approaches to city terminals), or on extensions

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where traffic does not justify new infrastructure. However, this "shared track approach" ignores mechanical rail's high maintenance requirements, costs and disruptions to travel from periodic maintenance on these existing lines. It is claimed by maglev advocates that the use of a completely separate maglev infrastructure more than pays for itself with dramatically higher levels of all-weather operational reliability and almost insignificant maintenance costs, but these claims have yet to be proven in an operational setting as intense as many traditional rail operations, and ignore the difference in maglev and traditional rail initial construction costs. So, maglev advocates would argue against rail backward compatibility and its concomitant high maintenance needs and costs.

Efficiency: Due to the lack of physical contact between the track and the vehicle, maglev trains experience no rolling resistance, leaving only air resistance and electromagnetic drag, potentially improving power efficiency.

Weight: The weight of the electromagnets in many EMS and EDS designs seems like a major design issue to the uninitiated. A strong magnetic field is required to levitate a maglev vehicle. For the Transrapid, this is between 1 and 2 kilowatts per ton. Another path for levitation is the use of superconductor magnets to reduce the energy consumption of the electromagnets, and the cost of maintaining the field. However, a 50-ton Transrapid maglev vehicle can lift an additional 20 tons, for a total of 70 tons, which consumes between 70 and 140 kW. Most energy use for the TRI is for propulsion and overcoming the friction of air resistance at speeds over 100 mph.

Noise: Because the major source of noise of a maglev train comes from displaced air, maglev trains produce less noise than a conventional train at equivalent speeds. However, the psychoacoustic profile of the maglev may reduce this benefit: a study concluded that maglev noise should be rated like road traffic while conventional trains have a 5–10 dB "bonus" as they are found less annoying at the same loudness level.

Design Comparisons: Braking and overhead wire wear have caused problems for the Fastech 360 railed Shinkansen. Maglev would eliminate these issues. Magnet reliability at higher temperatures is a countervailing comparative disadvantage (see suspension types), but new alloys and manufacturing techniques have resulted in magnets that maintain their levitational force at higher temperatures.

Control Systems: There are no signalling systems for high or low speed maglev systems. There is no need since all these systems are computer controlled. Besides, at the extremely high speeds of these systems, no human operator could react fast enough to slow down or stop in time. This is also why these systems require dedicated rights of way and are usually proposed to be elevated several meters above ground level. Two maglev system microwave towers are in contact with an EMS vehicle at all times for two-way communication between the vehicle and the central command centre's main operations computer. There are no need for train whistles or horns, either.

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COMPARISON WITH AIRCRAFT

For many systems, it is possible to define a lift-to-drag ratio. For maglev systems these ratios can exceed that of aircraft (for example Inductrack can approach 200:1 at high speed, far higher than any aircraft). This can make maglev more efficient per kilometer. However, at high cruising speeds, aerodynamic drag is much larger than lift-induced drag. Jet transport aircraft take advantage of low air density at high altitudes to significantly reduce drag during cruise, hence despite their lift-to-drag ratio disadvantage, they can travel more efficiently at high speeds than maglev trains that operate at sea level (this has been proposed to be fixed by the vactrain concept).

While aircraft are theoretically more flexible, commercial air routes are not. High-speed maglevs are designed to be trip-time competitive with flights of 800 kilometers/500 miles or less. Additionally, while maglevs can service several cities in between such routes and be on time in all weather conditions, airlines cannot come close to such reliability or performance.

Because maglev vehicles are powered by electricity and do not carry fuel, maglev fares are less susceptible to the volatile price swings created by oil markets. Travelling via maglev also offers a significant safety margin over air travel since maglevs are designed not to crash into other maglevs or leave their guide ways. Aircraft fuel is a significant danger during takeoff and landing accidents.

SAFETY

• ARE SUPER-CONDUCTING MAGNETS REALLY DEPENDABLE? WILL IT BE SAFE TO TRAVEL BY MAGLEV?

Superconducting magnets are highly reliable. High-energy accelerators routinely operate with many hundreds of superconducting magnets positioned along the path followed by particles that travel in precise orbits along miles of evacuated tubes. If only one of these many hundred magnets failed, it would shut down the accelerator for a long period while the magnet was repaired or replaced. Such a situation could not be tolerated, and in fact, does not occur in practice. In the proposed superconducting super collider (SSC), for example, over 10,000 superconducting magnets would have been positioned along the 76-kilometer circumference of the SSC. Failure of one of these magnets would have shut down the SSC. The Maglev vehicles are designed with multiple (typically 16) superconducting magnets that operate separately and independently of each other. The vehicle will remain levitated and operate safely even if several of its magnets were to fail. Because the failure rate of superconducting magnets is very low, the probability of two magnets failing in a period of few minutes, the time needed to reach a stopping point, would be less than once in a million years of operation. Such a failure rate is much smaller than the engine failure rate in jet aircraft. Furthermore, the Maglev vehicle would continue to operate, while the jet aircraft would not. In fact, it would take

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the simultaneous failure of at least 6 independent magnets to compromise levitation capability -a probability that is infinitesimally small compared to other modes of transport.

• WHAT HAPPENS IF THE ELECTRIC POWER IS CUT OFF TO A MAGLEV GUIDEWAY? WILL THE VEHICLES ON IT CRASH?

The Maglev vehicles are automatically and passively stably levitated as long as they move along the guideway. The electric power fed to the guideway magnetically propels the vehicles and maintains their speed. If the guideway power were cut off, the vehicles would coast for several 49 miles, gradually slowing down due to air drag. When they reach 30 mph, they settle down on auxiliary wheels and brake to a stop on the guideway. When power is restored to the guideway propulsion windings, the vehicles can magnetically accelerate back up to their cruising speed.Because the vehicles are automatically levitated and stabilized for speeds greater than 30 mph, there is no chance of a crash if guideway power is cut off.

• ARE THERE ANY HEALTH OR ENVIRONMENTAL HAZARDS FROM THE MAGNETIC FIELDS OF A MAGLEV VEHICLE?

There are no health and environmental hazards from the magnetic fields around the Maglev vehicle. The magnetic fringe fields from the quadrupole magnets on the vehicles drop off much faster with distance than do the fringe fields from dipole magnets. This rapid decrease in fringe fields allows the magnetic fields in the passenger compartment to be at Earth ambient level, ~ 0.5 Gauss. All humans live constantly in Earth's magnetic field and are adapted to it. They will experience no difference in field strength when they ride in a Maglev vehicle. In fact, people presently experience stronger magnetic fields than the Earth ambient value when they ride subways and electrified trains, when they operate electrically powered equipment in the home or when they walk down city streets. The magnetic fields in vehicles will be lower than in the above examples.

ACCIDENTS

August 11, 2006 fire in Shanghai Transrapid

On August 11, 2006 a fire broke out on the Shanghai Transrapid, shortly after leaving the Longyang terminal. This was the first accident on a maglev train in commercial operation. Train operation was shut down immediately. Passengers were able to disembark the train safely and no casualties were reported. Operations resumed on one line after some days. The fire was thought to have originated below the passenger compartment, possibly as a result of battery malfunction.

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Fig 13 Men trying to extinguish the fire in Shanghai Transrapid

ACCIDENT OF LATHEN TRANSRAPID, GERMANY

Fig. 14 The Accident site

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Fig. 15 The Collision with the maintenance vehicle

The 2006 Lathen Maglev train accident occurred on 22 September 2006 when a Transrapid magnetic levitation (maglev) train collided with a maintenance vehicle near Lathen, Germany. 23 people were killed, making this the first fatal accident on a maglev train.

THE MIYAZAKI FIRE INCIDENT

The MLU002 (Japan) test train was completely consumed in a fire in Miyazaki. As a result, the political opposition claimed maglev was a waste of public money. New designs were made.

Fig. 16 Water being sprayed to douse the fire

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FUTURE SCOPE AND EXPANSIONS

In the far future Maglev technology are hoped to be used to transport vast volumes of water to far regions at a greater speed eliminating droughts.

• Far more, space is an open door to maglev trains to propel space shuttle and cargo into space at a lower cost. Artist’s illustration of Star Tram, a magnetically levitated low-pressure tube, which can guide spacecraft into the upper atmosphere.• Scientists hope future technologies can get the train to operate at a 6000km/h, since theoretically the speed limit is limitless. But still it’s a long way to go.

• Toshiba Elevator and Building Systems Corp have developed the world’s first elevators controlled by magnetic levitation available as early as 2008.Using maglev technology capable of suspending objects in mid-air through the combination of magnetic attraction and repulsion they promise quieter and more comfortable travel at up to 300m per-minute, some 700m per-minute.

Thus, active collaboration and future joint ventures from all international bodies holds the future of these trains.