I try the rail using KK, but it does not work well. there are two problems exist.
If using straight rail to GSO, the optimization of the game will produce a small displacement. But this fatal displacement will cause the elevator hitting the rail and destruct it.
If placing rail indirectly, the rail upon 100km will shiver mysteriously. it will destruct the elevator when docking to the space part rail.
maybe I need to improve the mesh