The thing with the tightly curved track idea is it introduces many difficult problem while solving only a few less pressing problems - the problem I can think of would getting a long track of land and having to around that long track. But there's the centrifugal force, there's it's effect on any delicate machinery inside the capsule and there's the potential for electromagnetic weirdness from any charge in the capsule. Also, the curve track would mean that a capsule going off the rails could go in a totally unpredictable direction.

Also, you'd durability as well as raw strength of materials will come in here since they'll be trying to use the thing repeatedly.