System and method for detecting broken rail and occupied track from a railway vehicle

A method for testing conditions on a railroad track having parallel first and second rails, said method comprising:

• providing a plurality of shunts between the first and second rails at intervals along the railroad track, each shunt having at least one characteristic resonant frequency differing from those of adjacent shunts;
• providing a test unit on a railway vehicle on the railroad track;
• transmitting an electrical test signal from the test unit to the first rail to create a track circuit in which the test signal propagates along the first rail, through at least one of the shunts, returns to the railway vehicle along the second rail and through the wheels and axle of the railway vehicle;
• said test signal having predetermined electrical properties selected to interact with at least one of the shunts;
• receiving the test signal from the second rail at the test unit;
• and
• analyzing the received test signal to identify at least one predetermined condition concerning the status of the railroad track.