Asian Basic and Applied Research Journal

Road traffic management in major cities around the world has continued to be a subject of concern. Traffic Light System (TLS) is a stand-alone self-actuated application for coordinating the flow of traffic at busy road intersection of major cities while satisfying real-time constraints and requirement. Various attempts to ensure continuous dependable service delivery of conventional TLS have resulted to fail-safe designs. The fail-safe design allows the conventional TLS to experience downtime which is not good for a critical system like TLS. Hence, to develop a fault-tolerant TLS that could optimize reliable TLS service delivery; three Traffic Light Controller Units (TLCU1, TLCU2 and TLCU3) were interfaced together using the concept of triple modular redundancy architecture. A disagreement detector was configured to test the viability of the TLCUs which could result into zero (faulty condition) or one (good condition) using stationarity process. Markovian process was used to switch a faulty TLCU to another good one using majority voter mechanism. The fault-tolerant TLS and existing TLS were simulated using MATLAB R2015a. The performance of the fault-tolerant TLS was evaluated by comparing with that of existing TLS using reliability as performance metric. The simulation results revealed that the fault-tolerant TLS yielded 99.76 %, reliability while simulation results of the existing TLS yielded 30.64 %, reliability. This work has therefore developed a fault-tolerant TLS that outperforms the existing fail-safe TLS in terms of reliability.