Stackable triple vertical U-turn for Gravitrax

Hi, this is my first Gravitrax design published here. In contrast to the ring I prefer to print a ground plate with an integrated ring which is glued under the tile.

To see it in action you can look here:
https://www.youtube.com/watch?v=0o8dbjHdD4E

No support is needed.
The tunnels have got a higher opening, so that the marbles should nicely run through it even from a rail with a steep slope.

Feedback is appreciated.