Reliability Comparative Evaluation of Active Redundancy vs. Standby Redundancy

Redundancy is a commonly applied reliability improvement technique to enhance the system reliability and availability of safety critical systems, or operational impact systems in the railroad and mass transit industry. In this paper, two very basic but different types of parallel redundancy, namely active redundancy and standby redundancy are introduced and studied according to the mechanism structure built in a system. The pros and cons of the active redundancy and standby redundancy are also discussed. The Markov model technique is utilized to illustrate the Mean Time Between Failure (MTBF) calculation for the active and standby redundancy for the purpose of reliability evaluation. The comparison is also undertaken for the active redundancy versus standby redundancy from a reliability point of view.