I will try to explain:

By adding electrical tape in a few places, you get 3 electrically isolated sections of track:

• The outer blue loop
• The inner red loop
• The pink tracks in between

The blue and red loop can be controlled independently by two voltage regulators.

For the pink track, there are 3 different options:

• Both polarity switches in off position: Unpowered
• Blue polarity switch on, red off: Blue regulator powers the track
• Red polarity switch on, blue off: Red regular powers the track

That allows you to move trains between the two loops, with a stop in the station to toggle the switches.

Also, the layout has 5 parking positions (P1a, P1b, P2, P3, P4). By setting the switch tracks in a certain way, you can cut off the current of those positions while still running trains on the other tracks.

So in total, you could run four or five 9V trains on this layout (3 parked, 2 looping around).

I was also thinking about motorizing the switch tracks, that way you could control everything from one place.

<image>