Broken rail detector for communications-based train control and positive train control applications

An apparatus for detecting completely broken rails in an unoccupied section of railroad track without insulated joints, the section of track including two rails extending generally parallel to an axis corresponding to train movement and having a physical center, said apparatus comprising:

• means for subdividing the track section into current loops, each of the current loops comprising the two rails of the track and two loop terminations, wherein each loop termination is one of a hard-wired shunt and a turnout closure rail, and wherein each of the current loops is formed without any insulated joints separating it from any adjacent portion of the two rails;
• means for applying commercial AC power near the physical center, including means for causing, under a condition of the rails being intact, approximately equal currents to flow in each resulting half of the track section;
• means for sensing currents through induction of voltages in a coil mounted directly to the rails but electrically isolated from the rails;
• and
• means for detecting a rail break through detection of a subsequent decrease in the coil voltage resulting from a reduction of current due to the rail break in at least one half of the track section with respect to a reference value determined while the rails were intact and due to the break, wherein an absence of the detection reflects an intact state of the rails.