Wiring 4 crossings with one DPDT switch

First locate the 4crossing and glue it in place using Epoxy glue. Smear the glue all over the bottom of the rails. Press it in place. Put some weights on the 4xing until the glue cures (24 hours)
Then (using a dremel with a cut off disk) cut the gaps as indicated in the drawing.
Not all rails are cut both sides so be sure you just cut the rails as indicated.
The back of the dpdt switch is wired criss-cross with the positive and negative wires. These positive and negative wires are hooked up (in addition to the criss-cross on the switch) to the 4 positive and 4 negative places on the 4crossings. Then the 4-A's are hooked to the A position on the switch and the 4-B's are hooked to the B position on the switch.

This makes the crossings work as east-west or throw the switch and the crossings work as north south.

Let me know if you have questions.
Is the diagram clear enough?