Road traffic congestion affects our daily lives whether we drive or take bus transit. However, the complexity of road traffic congestion and its causes are active research areas because there is a need to find plausible solutions to improve traffic flow. Given the abundance of traffic signal performance data collected by transportation agencies, we have an opportunity to analyze traffic signals to identify parameters (cycle length and green time) that can be improved. We have performed a comprehensive overview of the methods used to find traffic signal timing issues by looking at the research within the last five years. We found that newer research focuses on connected vehicles (CV) and adaptive control systems, including Reinforcement Learning techniques. This paper also discusses a case study of retiming traffic signals in the highly populated Las Vegas Valley.