In the 20th century, the invention of the airplane forever changed the way people moved from place to place across the world. Offering a fast, convenient mode of transportation opened up commerce and travel on a scale previously undreamt of. But with the high cost of airline tickets and the boundless use of fossil fuels needed for flight, many people in the 21st century are looking toward to the constructions of high speed Maglev trains to cope with the population’s ever increasing transportation demands. But how do maglev trains actually work?
If you’ve ever studied magnetism in school, you’ll remember that a magnet has two “poles”, labeled North and South. In magnetism, opposites attract, while pushing the like poles together exerts a repelling force. In a maglev train, engineers utilize this repelling force to lift the train above the track, eliminating friction, allowing the train to travel far more efficiently. By aligning coils of magnetized wire along a track, known as a guideway, and attaching magnets with the same polarity to the underside of a train, lift is achieved. This lack of friction, in addition to increasing efficiency, allows maglev trains to accelerate easily. When combined with a solid aerodynamic design, they can easily reach speeds of more than 310 mph.
Unlike the permanent magnets that decorate your refrigerator, Maglev trains make use of electromagnets. In an electromagnet, the magnetic force exerted is dependant on the flow of electrons through a coil of wire. Used in Maglev trains, this means two things: Firstly, an electrical power source is needed to generate the magnetic force. Secondly, since the direction of the magnetic field varies with direction of electron flow, rapidly switching the direction electrons are traveling can help to move the train along the track. When the magnets ahead of the train are polar opposites of those on the train, it will “pull” the train forward. Magnets with the same polarity as those on the train can “push” it from behind. By taking advantage of this property of magnetism, engineers have eliminated the need for a conventional motor to propel the train.
Although specific designs vary considerably, Maglev trains generally float anywhere between 1cm and 10cm above the track. Engineers in Germany have developed an electromagnetic suspension (EMS) system known as Transrapid, in which the bottom of the train is wrapped around a steel guideway. Because it relies solely on the electromagnetic force, it rests permanently on a layer of air even when at a standstill. This, of course, means more electricity needs to be continually supplied, and in the event of a malfunction, it relies on a back up battery to keep the train aloft.
Japanese engineers, in contrast, are focusing on the use of super-cooled, superconducting electromagnets in an electrodynamic (EDS) system. Because the magnets used in the EDS system continue to conduct electricity when the power source is removed, this system has the benefit of increased safety in the event of power failure. The use of super-cooled coils is far more energy efficient than a standard EMS system, but the technology required to chill the coils is expensive to manufacture and operate.
By utilizing the basic properties of electromagnetism, Maglev trains have a number of distinct advantages to traditional transportation methods. Cleaner, faster, cheaper, and more environmentally sound than competing modalities, the development of maglev trains has the potential to profoundly transform the way people travel in the 21st century. As they become increasingly more common, new infrastructure and further refinement of the technology will help launch us into the future.