Automatic Signalling using optical detectors for train detection is also possible. These can be used to control a block of track, a signal at one end is green and the other red, once the train passes the green signal both signals are red until the block is cleared. As the train approaches the red signal (with the block clear) the far signal will change from green to red and after a short delay the signal in front of the train will turn to green for the train to proceed. This could also be used with the servo controller for semaphore signals.

Instructions and explanation of operation for 2 Aspect Signal Control downloaded here.

The price for the signal controller for 2 aspect lights is expected to be $50 and user configured for any of the signal applications in the Instructions.
With the addition of the 2 position 2 Servo controller it can also be used to automate Semaphore signals.

A signal controller for more prototypical signals is in development. Modellers suggestions are most appreciated on the features that would enhance you models. Signal Planning Victorian Railways.