Abridgment of shunting of track circuit in a polyphase system of continuous inductive train control

Investigations into shunting of train control track circuits have been made in the field under operating conditions by observing the operation of the primary relay on a locomotive as a train runs into a track circuit´ in which there is a train ahead or an open switch and similar data have been obtained on the performance of the relay on trains in regular service. It is intended in this paper to present a method for predetermining the shunting characteristics of train control track circuits. The system discussed is a polyphase system of continuous inductive train control with cab signals employed on double-tracked steam roads. Curves are given which describe shunting conditions in train control track circuits and data are also given for comparison describing the shunting of the track relay on the same sections of track.