How do magnetic railways work

Figure 1 Transrapid on testing center in Germany near Bremen. Figure 3 Comparison of Wheel-Rail versus Guideways.

Figure 4 Levitation, propulsion, and guidance in maglev. Levitation Levitation is the ability for the train to stay suspended above the track. There are two important types of levitation technology: Electromagnetic Suspension EMS : EMS Figure 5 uses the attractive force of electromagnets placed on the guideway and on the train to achieve levitation.

The benefits of this method are that it is simpler to implement than Electrodynamic Suspension discussed below , and that it maintains levitation at zero speed. The drawbacks are that the system is inherently unstable. At high speeds, it becomes difficult to maintain the correct distance between train and guideway. If this distance cannot be kept, the train will fail to levitate and come grinding to a halt.

To account for this, EMS requires complex feedback-control systems to ensure the train is always stable Lee, Electrodynamic Suspension EDS : EDS Figure 6 uses the repulsive force of superconducting magnets placed on the guideway and on the train to achieve levitation.

The magnets move past each other while the train is running and generate the repulsive force. The benefits of this method are that it is incredibly stable at high speeds.

Maintaining correct distance between train and guideway is not a concern Lee, The drawbacks are that sufficient speed needs to be built up in order for the train to levitate at all. Additionally, this system is much more complex and costly to implement. Propulsion Propulsion is the force that drives the train forward. Figure 7 Rotary motor versus linear motor.

Guidance Guidance is what keeps the train centered over the guideway. Benefits of Maglev The most obvious attraction of maglev trains is that they can travel faster than traditional rail trains. There are other, more subtle qualities that also make maglev attractive: Longevity: Conventional wheels and rails undergo a great deal of stress over time.

They must be replaced and repaired periodically to remain functional. In maglev, there is no contact between train and guideway, so there is substantially less wear-and-tear. The lifespan of maglev parts are appropriately much longer due to this fact Powell, Economically, this is quite an incentive, as repair and maintenance are costly and time-consuming activities.

Safety: It might seem counter-intuitive that these trains are safer, as they travel so much faster than their wheeled counterparts. It is true nevertheless. Maglev trains are near impossible to derail Luu, It would take something like complete guideway collapse to part a train from its track. Finally, it is easy to elevate the guideways. If the trains are running on tracks ten feet above the ground, there is a smaller chance of collision with an object on its path Luu, This gives them an advantage in efficiency Wang Energy consumption is essential to the success of a transportation system.

Much of the cost of operating one goes to paying for power. Therefore this edge in efficiency is very important. However, while maglev trains are more efficient, they are currently not substantially more efficient than modern high-speed rail. They do, though, have the potential to be far superior in this category.

Environmental Impact: Maglev trains can make tighter turns than high-speed rails can. This allows guideways to be built which can navigate terrain much better Wang The paths can be engineered to have as little effect on the environment as possible. Guideways also take up less area than rails do Wang This further reduces environmental impact. And, as noted before, guideways are easily elevated off the ground Luu, Plants and animals alike are safer with the the train traveling above them, and not barreling by right next to them.

However, noise reduction is still considered a positive feature. Maglev trains are quieter than contemporary trains, so this is another point in their favor Wang, Drawbacks of Maglev Although there are many upsides, there are still reasons why maglev trains are not being built everywhere. Electrical Engineering in Maglev Ever since the steam engine, trains have traditionally been in the domain of mechanical engineers. The Future of Maglev Maglev technology holds great promise for the future.

Bibliography kph Hayabusa matches world speed record. The Japan Times. Fast Track. North American Maglev Transportation Institute. Linear Synchronous Motion 2nd Edition. Review of Maglev Train Technologies. DOI: Maglev: The Train of the Future.

University of Pittsburgh Swanson School of Engineering. The Future of Maglev. Maglev Trains. Search the Handbook:. Design Process 2. Management 3. One potential drawback in using the EDS system is that maglev trains must roll on rubber tires until they reach a liftoff speed of about 93 mph kph. Japanese engineers say the wheels are an advantage if a power failure caused a shutdown of the system. Also, passengers with pacemakers would have to be shielded from the magnetic fields generated by the superconducting electromagnets.

The Inductrack is a newer type of EDS that uses permanent room-temperature magnets to produce the magnetic fields instead of powered electromagnets or cooled superconducting magnets.

Inductrack uses a power source to accelerate the train only until it begins to levitate. If the power fails, the train can slow down gradually and stop on its auxillary wheels. The track is actually an array of electrically shorted circuits containing insulated wire. In one design, these circuits are aligned like rungs in a ladder. As the train moves, a magnetic field repels the magnets, causing the train to levitate.

Inductrack I is designed for high speeds, while Inductrack II is suited for slow speeds. Inductrack III is specifically designed for very heavy cargo loads moved at slow speeds. Inductrack trains could levitate higher with greater stability. As long as it's moving a few miles per hour, an Inductrack train will levitate nearly an inch 2. A greater gap above the track means that the train would not require complex sensing systems to maintain stability.

Permanent magnets had not been used before because scientists thought that they would not create enough levitating force. The Inductrack design bypasses this problem by arranging the magnets in a Halbach array. The magnets are configured so that the intensity of the magnetic field concentrates above the array instead of below it. They are made from a newer material comprising a neodymium-iron-boron alloy, which generates a higher magnetic field. The Inductrack II design incorporates two Halbach arrays to generate a stronger magnetic field at lower speeds.

Notably, the passive magnetic levitation concept is a core feature of proposed hyperloop transportation systems, which is essentially an Inductrack-style train that blasts through a sealed tube that encases the entire track.

It's possible that hyperloops may become the approach of choice, in part because they dodge the issue of air resistance in the way the regular maglevs cannot, and thus, should be able to achieve supersonic speeds. Some say that a hyperloop might cost even less than a traditional high-speed rail line. But whereas maglev trains are already a proven technology with years of operational history, no one has yet built a commercial hyperloop anywhere in the world [source: Davies ].

While maglev transportation was first proposed more than a century ago, the first commercial maglev train didn't become a reality until , when a low-speed maglev shuttle became operational between the United Kingdom's Birmingham International railway station and an airport terminal of Birmingham International Airport. Since then, various maglev projects have started, stalled, or been outright abandoned. However, there are currently six commercial maglev lines, and they're all located in South Korea, Japan and China.

The fact that maglev systems are fast, smooth and efficient doesn't change one crippling fact — these systems are incredibly expensive to build. Some critics lambast maglev projects as costs perhaps five times as much as traditional rail lines.

But proponents point out that the cost of operating these trains is, in some cases, up to 70 percent less than with old-school train technology [sources: Hall , Hidekazu and Nobuo ]. It doesn't help that some high-profile projects have flopped. The administration at Old Dominion University in Virginia had hoped to have a super shuttle zipping students back and forth across campus starting back in the fall semester of , but the train did a few test runs and never really approached the 40 mph 64 kph speeds it promised.

But other projects persist. One ambitious group wants to build a mile kilometer stretch from Washington D. The concept's exorbitant price tag might be laughable just about anywhere else in the world, but this region's soul-crushing gridlock and limited space means city planners and engineers need an innovative solution, and a super-fast maglev system might be the best option.

A key selling point — an expansion to this project could connect to Washington to New York city and cut travel times to just 60 minutes, a speedy commute that could transform commerce and travel in the Northeast [sources: Lazo , Northeast Maglev ].

In Asia, though, the maglev boom is essentially already underway. Japan is working feverishly on a Tokyo-to-Osaka route that may open by When it's complete, the train will slash the nearly three hour trip to just 67 minutes [source: Reuters ].

China is seriously considering dozens of potential maglev routes, all of them in congested areas that require high-capacity mass transportation. These won't be high-speed trains. Instead, they'll move lots of people over shorter distances at lower speeds. Nevertheless, China manufactures all of its own maglev technologies and is about to unveil a third-generation commercial maglev line with a top speed of around mph kph and — unlike previous versions — is completely driverless, relying instead on computer sensors for acceleration and braking The country already has some maglev trains in operation but they need a driver.

It's impossible to know exactly how maglevs will figure into the future of human transportation. Advances in self-driving cars and air travel may complicate the deployment of maglev lines.

If the hyperloop industry manages to generate momentum, it could disrupt all sorts of transportation systems. These magnetic fields interact with simple metallic loops set into the concrete walls of the Maglev guideway. The loops are made of conductive materials, like aluminum, and when a magnetic field moves past, it creates an electric current that generates another magnetic field.

Three types of loops are set into the guideway at specific intervals to do three important tasks: one creates a field that makes the train hover about 5 inches above the guideway; a second keeps the train stable horizontally. Both loops use magnetic repulsion to keep the train car in the optimal spot; the further it gets from the center of the guideway or the closer to the bottom, the more magnetic resistance pushes it back on track.

The third set of loops is a propulsion system run by alternating current power. Here, both magnetic attraction and repulsion are used to move the train car along the guideway. Imagine the box with four magnets -- one on each corner. The front corners have magnets with north poles facing out, and the back corners have magnets with south poles outward. Electrifying the propulsion loops generates magnetic fields that both pull the train forward from the front and push it forward from behind.