A railroad train detector and communication system relies on the track rails for communicating information among a plurality of locations. The equipment located at each of the locations eliminates relay based current detection, relay based current transmission, and relay based logic functions, and rather these functions are implemented with microprocessors. An extent of signal trackway is defined between a pair of head ends, intermediate the head ends at intermediate insulated joint locations, a microprocessor implemented transmitter/receiver pair is provided. One half of the transmitter/receiver pair manages communication flow for each direction of information flow at the joint. At each of the head locations, only a single transmitter/receiver is required. Associated with each microprocessor in a transmitter/receiver is auxiliary apparatus to couple the microprocessor's input/output ports to the track rails themselves. This auxiliary apparatus includes non-relay based track signal detector (or receiver) for sensing current flow in the track rails, a track current generator for transmitting information through the track rails and optionally a non-relay based approach detector to sense changes in track current flow. Based on signals detected in the track rail, the microprocessor of a receiver for example can determine the occupancy condition of a portion of the railroad track rails between the receiver and associated transmitter. Based on the signals, therefore, the microprocessor outputs an indication identifying the occupancy/non-occupancy condition of this portion of the track rails.