While answering one question, I remembered an old trick for preventing crossing wires while connecting feeder lines and laying track. It’s just a simple audio continuity tester.
You need a piezo element, a 9 volt battery holder, 9 volt battery, a pair of insulated alligator clips and some wire.
Make a simple circuit by connecting one wire from the battery holder to the piezo element, the other wire from the battery holder to an alligator clip. Connect a wire to the other terminal of the piezo and a alligator clip on the other end. Connect the battery and test the circuit by touching the clips together.
Now connect the clips to the bus wire or track terminals and/or rails. As you are laying track and feeder wires, If you connect the wrong wires or have a short from a reverse loop, the buzzer will sound.
Having an alarm sound the instant you make a mistake is better than trying to find a short when your finished.