Abstract: A model train system including a track interface unit for bi-directional communication with one or more trains; and a communication circuit installed in the one or more trains that communicates with the track interface unit in a bi-directional manner, the communication circuit communicating to the track interface unit information regarding a current speed of said one or more trains, the communication circuit being configured so as to be capable of receiving an integrally formed command/power signal and processing the command signal independently of the power signal.