With all the talk about transcontinental bullet trains, I thought that the whole subject merited a more ambitious approach.
It’s quite difficult to accelerate a train using only the friction of drivewheels on a metal track…especially as reducing the weight of the rolling components is a good thing for fuel efficiency.
Today’s invention is therefore a railway on which a very long train runs which consists of a series of low profile, lightweight carriages (something like those trains which I’ve seen crossing Canada which take half a day to pass…except very much longer).
On top of them, a set of lightweight rails allows another layer of carriages to operate at increased groundspeed (a short train running on a train which is say, half the length of the track, will run at three times its normal speed).
This approach might be extended, given very low-cost rolling stock and in the absence of low bridges, to allow speed multiplication by higher factors.