Lifespan Prediction of Traffic Signal Controllers

Traffic signal controllers are devices that regulate the timing and operation of traffic signals at roadway intersections. Signal controllers are vital to an overall traffic management system, ensuring traffic flows efficiently and safely at intersections. Traffic signal controllers can fail for several reasons, but there is limited knowledge of signal controller failure mechanisms in previous research. Understanding the failure methods can help predict the lifespan of traffic signal controllers. This study was the first known attempt to analyze full lifespan of a traffic signal controller using a fault tree model. The study compares fault tree analysis output with existing methods for life cycle prediction. The lifespan obtained from the literature ranged from 4 to 20 years; the Weibull survival probability model suggested a lifespan of about 7 years, and fault tree analysis provided a lifespan of 8 years. In addition, a sensitivity analysis (+/- 20%) was performed to address uncertainty with the inputs for fault tree analysis, which predicted a range between 5.75 and 11 years. Transportation agencies can use life span predictions to estimate funding needs and improve asset management practices.