>you have tight bends in the corners and then those collapse down to a pole point for the next station.
Sorry i am not sure if i understand it right. I tried to understand what you mean from project file you provide, but i don't understand what those circles mean.

Oh maybe you mean this difference in shapes ? Yes the profile in center should have the shape of a rail curve flatten.


>Little skinny pieces are because of sharp corners not being aligned.
How they should be aligned ? I checked all profile curves (except rails) to doesn't have tilt.
I also tried to build them such a way so they touch rail curves with control points but it doesn't help much.

I attached a project file with result shape i construct with extrude, loft, shamfer and fillet.

> But for more square like shapes that also have smooth edges and tilt (so they not easy to trim or extrude) i still don't know what to do.
This one in result have sharp edge here.


And if you try to create tilt on a rounded corner part by trimming or extrude you lose roundness.


You may create loft surface (not solid) and boolean-merge it. But the result edge that connect loft part and extruded part also will be sharp.