Another option to "invert" the logic is to use the COM-NC relay contacts instead of COM-NO relay contacts. This may or may not apply to your application. For example, one school of thought with fail-safe type circuits is to ask what happens if the fail-safe circuit itself "fails"; for example what happens if the 5V power supply drops out? The relay would then connect COM-NC so one would argue this should be the relay position that disconnects power to the trains … i.e., dead-man switch.
