Asian Research Journal of Current Science

Traffic Light System TLS is an optimistic autonomous application that leverages the urban road intersections to offer globally better and more efficient traffic management. Due to the limitation of carrying capacity of roads and the high cost of road expansion, deploying TLS to intersections remains the most embraced traffic management technology across the world. Despite this credit, TLS like any other system usually experience downtime which are accounted for by failure of their Traffic Light Controller Unit TLCU.  Such downtime result in several catastrophic scenario ranging from loss of time, loss of resource, accidents, and air pollution. This paper proposes an effective and adaptive fault tolerant traffic controller switching model in an effort to reduce downtime of TLS and thereby improve the maintainability of the TLS. The proposed method made use of three Traffic Light Controller Units (TLCUs) which were interfaced together using the concept of Triple Modular Redundancy (TMR) architecture. Intermittently, a disagreement detector was configured to test the viability of the primary TLCU using stationarity process. Markovian process was used to switch a faulty primary TLCU to another through the majority voter mechanisms. The proposed fault-tolerant TLS and Existing TLS were simulated using MATLAB version R2015a and the performance of the systems was evaluated using maintainability as a performance metric. Empirical results prove that the fault-tolerant TLS outperformed the existing fail-safe TLS in terms of maintainability.