[rallyhub]

Nice idea: At 4:35 you can find a loop without flipper, because it is positioned in a bend:

 

[rallyhub]

i wonder why both rails of the loop are isolated. Though surely only the return leg of the outer loop needs isolating but both outer legs are
[/QUOTE]

I am not an electrical expert, but you need to be able to separate the loop from the main track for changing direction. So they isolated the whole loop (+ and -) from the main track (+ and - or - and +).
During the passing of the loop, the car changes the direction on the main track.
It would be nice if someone here on SlotForum would be so kind to add an electrical diagram of this circuit. I guess it is an analog track.

 

[rallyhub]

You need two of these

Thank you for your explaining.
I was already wondering what function those tabs in the slot have in the video on 1:35 (low loop) and 4:34 (high loop).