Maglev

Maglev, or magnetic levitation, is a system of transportation that suspends, guides and propels vehicles, predominantly trains, using magnetic levitation from a very large number of magnets for lift and propulsion. This method has the potential to be faster, quieter and smoother than wheeled mass transit systems. The power needed for levitation is usually not a particularly large percentage of the overall consumption; most of the power used is needed to overcome air drag, as with any other high speed train.
The highest recorded speed of a Maglev train is 581 kilometres per hour (361 mph), achieved in Japan in 2003, 6 kilometres per hour (3.7 mph) faster than the conventional TGV speed record.
The first commercial Maglev "people-mover" was officially opened in 1984 in 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 and design problems.
Perhaps the most well known implementation of high-speed maglev technology currently operating commercially is the IOS (initial operating segment) demonstration line of the German-built Transrapid train in Shanghai, China that transports people 30 km (18.6 miles) to the airport in just 7 minutes 20 seconds, achieving a top speed of 431 km/h (268 mph), averaging 250 km/h (160 mph).

First patents
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 (June 21, 1902) and U.S. Patent RE12,700 (August 21, 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 (August 25, 1959). The first use of "maglev" in a United States patent was in "Magnetic levitation guidance" by Canadian Patents and Development Limited

Technology Overview
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), electromagnets in the train attract it to a magnetically conductive (usually steel) track.
• Electrodynamic suspension (EDS) uses electromagnets on both track and train to push the train away from the rail.
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.

Advantages and disadvantages
Compared to conventional trains
Major comparative differences between the two technologies lie in backward-compatibility, rolling resistance, weight, noise, design constraints, and control systems.
• Backwards Compatibility: Maglev trains currently in operation are not compatible with conventional track, and therefore require all new infrastructure for their entire route. 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 where traffic does not justify new infrastructure.
• 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 large electromagnets in many EMS and EDS designs is a major design issue. A very strong magnetic field is required to levitate a massive train. For this reason one research path is using superconductors to improve the efficiency of the electromagnets, and the energy cost of maintaining the field.
• 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.
As with many technologies, advances in linear motor design have addressed the limitations noted in early maglev systems. As linear motors must fit within or straddle their track over the full length of the train, track design for some EDS and EMS maglev systems is challenging for anything other than point-to-point services. Curves must be gentle, while switches are very long and need care to avoid breaks in current. An SPM maglev system, in which the vehicle is permanently levitated over the tracks, can instantaneously switch tracks using electronic controls, with no moving parts in the track. A prototype SPM maglev train has also navigated curves with radius equal to the length of the train itself, which indicates that a full-scale train should be able to navigate curves with the same or narrower radius as a conventional train.
• Control Systems: EMS Maglev needs very fast-responding control systems to maintain a stable height above the track; this needs careful design in the event of a failure in order to avoid crashing into the track during a power fluctuation. Other maglev systems do not necessarily have this problem. For example, SPM maglev systems have a stable levitation gap of several centimeters.

A Maglev train has it advantages and disadvantages. Hence you cannot say which train, whether the Maglev train or the conventional train is the best but I think that it should depend on the person riding it whether which train is more suitable for himself.