Traffic Signal Systems: A Review of Current Technology in the United States

Traffic signal systems have been employed since the early twentieth century as a method of continuously managing traffic flow and saturation at intersections and to promote smooth and safe automobile transportation. Due to the continuous increase of traffic congestion in urban areas, there is a need for further evaluation and implementation of traffic signal systems. This study reviews and consolidates information on a wide variety of signal systems, detection devices and communications components in order to provide a cogent understanding of current technology in the United States. Additionally, the assessment focuses on operational functions of various systems, and thereby, establishes what the systems’ capabilities are when utilized to their fullest extent. Current signal system practices are reviewed to compare existing technologies, and postmodern technologies are investigated. Recommendations for further investigation of traffic signal systems are also provided.