The rightful of conception of dangerous and protective faults to notify saety of railway signalling systems (RSS) is shown. Error of calculations, based on dangerous faults conseption, of RSS safety level is evaluated. The new method, based on „dangerous” element conception, of creation of safety models of RSS is propossed. Three versions of markov models is developed to evaluate parameters of RSS safety for vareous system configurations, the technology of their computer realisation is proposed too