Hi WilliamJ,
Your layout looks really nice from what I can see in the pictures. Good job!
You need to electrically isolate the outer loop switches from the inner loop switches at the center rail joint. Probably the easiest thing to start with is to pull up just enough track on the outer loop to remove the two outer loop switches. Turning the switches over, you can then put some insulating tape over the center rail phosphor bronze contact wipers where they contact the inner loop switch wipers. Also, it would be a good idea to put a piece of insulating tape on the ends of the diverging route center rails, to make double sure they don't touch and and make electrical contact with the center rails on your inner loop switches. Then reassemble all your switches and track, and this completes the electrical isolation of the two loops. The last step of course is to power each loop however you so desire.
Hope this helps. 
