Train transport vision : Japan's maglev trains

The basic principle behind maglev (derived from magnetic levitation) trains is quite simple: Install superconducting magnets in the underbelly of a train so that when the magnets come close to the steel railway cage, electromagnetic forces strong enough to counteract the weight of the train, as well as be able to accelerate it, are created. Instead of rolling across the rails, the train floats just above them, providing smooth, fast, and friction-free travel. That oversimplification, is to give you the gist of it. For concise background information you may read the related Wikis offered at the bottom.

Well. that's the theory. In practice, only a few high-speed maglev trains have actually been built, and to date only one - the shuttle from Pudong Airport to downtown Shanghai, China - operates in regular service. But testing continues elsewhere in the world, most notably in Japan, where authorities are pushing forward to launch a major maglev train service, where the first part will be connecting Tokyo and Nagoya by 2027, and its extension connecting Nagoya and Osaka by 2045. Traveling the 515 km (320 miles) from Tokyo to Osaka by Shinkansen bullet train currently requires 2 hours and 25 minutes. In 2045, travel between Japan's two largest metropolis will take just over one hour. The over 9 trillion Yen project was first proposed in the 1970s, but was repeatedly postponed due to its very high costs, most of which stem from an extensive network of tunnels that will represent 60% of the route. Trains will propel forward with the astonishing speed of more than 500 km/h (310 m/h).

Currently Japan holds the world speed record with 580 km/h. Researchers at Southwest Jiaotong University in China are developing  a maglev train that travels through a vacuum tube (also known as vactrain) to reach speeds of 1,000 km/h (620 mph). They say the technology can be put into operation in 10 years.

.a brief comparison with airplanes (extracted from the referenced Wiki)

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 guideways. Aircraft fuel is a significant danger during takeoff and landing accidents.

Read more :

[Ref.] http://en.wikipedia.org/wiki/JR–Maglev

[Ref.] http://en.wikipedia.org/wiki/Maglev

[Ref.] http://en.wikipedia.org/wiki/Vacuum_tube_train