Maglev explained

Maglevs (Magnetically levitated trains)

Introduction

The principal of a Magnet train is that floats on a magnetic field and is propelled by a linear induction motor. They follow guidance tracks with magnets. These trains are often refered to as Magnetically Levitated trains which is abbreviated to MagLev. Although maglevs don't use steel wheel on steel rail usually associated with trains, the dictionary definition of a train is a long line of vehicles travelling in the same direction - it is a train.

How it works

A maglev train floats about 10mm above the guidway on a magnetic field. It is propelled by the guidway itself rather than an onboard engine by changing magnetic fields (see right). Once the train is pulled into the next section the magnetism switches so that the train is pulled on again. The Electro-magnets run the length of the guideway.

What is the advantage of Maglev?

Well it sounds high-tech, a floating train, they do offer certain benefits over conventional steel rail on steel wheel railways. The primary advantage is maintanance. Because the train floats along there is no contact with the ground and therefore no need for any moving parts. As a result there are no components that would wear out. This means in theory trains and track would need no maintanence at all. The second advantage is that because maglev trains float, there is no friction. Note that there will still be air resistance. A third advantage is less noise, because there are no wheels running along there is no wheel noise. However noise due to air disturbance still occurs. The final advantage is speed, as a result of the three previous listed it is more viable for maglev trains to travel extremely fast, ie 500km/h or 300mph. Although this is possible with conventional rail it is not economically viable. Another advantage is that the guidway can be made a lot thicker in places, eg after stations and going uphill, which would mean a maglev could get up to 300km/h (186mph) in only 5km where currently takes 18km. Also greater gradients would be applicable.

What is the disadvantages with Maglev

There are several disadvantages with maglev trains. Maglev guide paths are bound to be more costly than conventional steel railways. The other main disadvantage is lack with existing infrastructure. For example if a high speed line between two cities it built, then high speed trains can serve both cities but more importantly they can serve other nearby cities by running on normal railways that branch off the high speed line. The high speed trains could go for a fast run on the high speed line, then come off it for the rest of the journey. Maglev trains wouldn't be able to do that, they would be limited to where maglev lines run. This would mean it would be very difficult to make construction of maglev lines commercially viable unless there were two very large destinations being connected. Of the 5000km that TGV trains serve in France, only about 1200km is high speed line, meaning 75% of TGV services run on existing track. The fact that a maglev train will not be able to continue beyond its track may seriously hinder its usefulness.

A possible solution

Although I haven't seen anywhere a solution could be to put normal steel wheels onto the bottom of a maglev train, which would allow it to run on normal railway once it was off the floating guideway.