I respectfully beg to differ with those who just wire turnout position indicators to the panel switch - unless the switch motor is a tortoise and the UNIdirectional LEDs are used to set machine power polarity.
Unless the indicators are wired through contacts on twin-coil machines, they will ONLY tell the direction the toggle (or slide) switch is thrown, not what the machine actually did.
My indicators are set up as a cascade circuit, one in each track line of the hidden yard. Five indicators, four twin-coil machines, positive data about which track has been selected. As a result, I can use the least expensive switch power arrangement - probe and stud. Since the indicators take a close approximation of no power, I can (and do) use salvaged communications cable wire, about #24, to connect machine contacts to panel.
By using an AC power source and diode-dividers at both studs and switch machines, I cut the wiring for switch machine power to a single wire from panel to machine. All it takes is four twelve for a dollar diodes, and the saving in heavier-gauge wire more than covers that AND the indicator circuit.
Chuck (Modeling Central Japan in September, 1964)