The article presents issues concerning on the alarm columns of highway emergency communication system. The system is presented in general and then the reliability-exploitation analysis was done. This enabled preparing a development graph of the relationship, under which is created a set of Kolmogorov-Chapman equations describing the system. On this basis, it was possible to find the relation for calculating the probabilities of system staying (in symbolic terms) in the functional: states of full ability SPZ, impendency over safety SZB and unreliability of safety SB.