Regional computer interlocking system (RCIS) is a safety critical computer system that features centralized control, centralized dispatch and less maintenance, so the reliability and security analysis of the RCIS counts for much. There are two diverse regional computer interlocking schemes in China, namely, the centralized interlocking scheme and the distributed interlocking scheme. The former exist risk caused by the central interlocking equipment fault which will affect the entire region to paralyze, while the latter has a high upfront investment and is not suitable for small stations. Hence, after comprehensive consideration of the advantage and disadvantage of the two schemes we can combine the above two schemes to solve the contradiction. Under the consideration of diagnostic coverage rate, repairable rate and common-cause failure, the Markov model of the combination of two interlocking scheme was established, based on the model the paper analyzed its reliability and security and compared with centralized interlocking scheme. Results shows that the scheme of combining the two regional computer interlocking scheme has a higher reliability and security than centralized interlocking scheme, and it is an ideal realization scheme not only for station, but also for interval.
