MSimon wrote:Think of the air blast blowing the ballast from the track. I don't think that will work. Plus I think you will need some kind of half tube (i.e. side rails) to keep the train unequivocally on the track.
The amount of surface load (and thus ballast required) is a lot less than with wheeled track. Keep in mind that on hovertrains, the load of the train's weight is distributed equally across the track's surface, not concentrated on specific points along a narrow track.
In theory, a hovertrain could run happily on an asphalt freeway. The only problem you're going to have in that case is guidance, e.g. keeping the train on the track.
Please look up Inductrack. It will change your mind about that statement. Inductrak is just about the cheapest track around.
Does the per-mile cost also take into account the amount of support structures required for Inductrack? Is the load distribution for Inductrack more beneficial when you compare it to 'regular' train track?
Furthermore, mag-lev systems still have the drawback of requiring powerful magnetic fields, which makes either the track or the vehicles expensive.
I foresee a disaster with the air-cusion rail system. A heavy snow blankets the track and the vehicle on its air-cushion climbs up the snowpack and out of the track. Whoppee! What fun, we're flying...splat!
That depends on the size of the air cushion you're using and whether or not you've got some way of vertical guidance. If the cushion is only a few mm thick, the air pressure coming from the train at the front will probably clear the track of any debris which would cause derailment or other accidents.
Furthermore, you'd expect such a system to have a monitoring system that keeps track of the amount of clearance between the train and the track, and adjust the amount of hover accordingly.
If, for some reason, the train would 'run onto' some piece of debris which threatens it with vertical derailment, the distance monitoring system would pick up the train is rising, and drop hover pressure until the normal situation is restored. It would happily run over any debris that is smaller than the expected gap, and if it encounters any bigger stuff, worst-case, it would just grind to a halt.
In extreme situations (like an imminent derailment) such a system would deploy some kind of emergency procedure which would stop the train safely.
WizWom wrote:A hovertrain could use partial offset, and still maintain enough contact with the rails to maintain control. by reducing the load on the wheels, the ride would be smoother and the maximum speed much faster.
You're going to need a way to supply power to the train anyway, so some mode of contact would be useful. However, any 'hard' contact points would induce friction, wear and heat where you don't need it.
You could also think of a modified LIM setup which would also transfer part of the power to the train's on-board systems. OTOH, that would require expensive coils along the length of the track, as opposed to a dragging contact or pantograph making contact with an electrified power line.
Because we can.
