On the conditions for the occurrence of hazardous failures in unlimited track circuits with a locomotive receiver in shunt mode operation

A comprehensive solution to the problem of determining the spatial coordinates of traction rolling stock units by primary safety devices based on the analysis of automatic locomotive signaling signals in modern train control systems based on unlimited track circuits is impossible without establishing the conditions for the occurrence of hazardous failures in shunt mode. This is of significant practical importance, since, in addition to receiving a clearance order inappropriate for the train situation, primary safety devices will not be able to refine the spatial coordinates of a traction rolling stock unit within the boundaries of the track circuit in question using signals received from the track line. In this article, based on the mathematical apparatus of track circuit theory and the four-terminal method, basic calculation expressions are derived for determining the value of the train safety criterion for shunt mode. A characteristic dependence has been obtained that allows one to estimate the extent of the danger zone under worst-case conditions for unlimited track circuits with a locomotive receiver. The obtained results form the basis for developing operating algorithms for a prospective train control system without trackside receivers.

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