Idling in a car waiting for the pre-timed traffic light to turn green can be frustrating, time consuming and a cause of air pollution. A 2023 simulation published in Applied System Innovation found that deploying smart traffic lights at a single key intersection in a small Portuguese city reduced CO2 emissions by 32 to 40 percent and wait times by 53 to 95 percent.

Smart traffic lights use a combination of sensors, including vehicle detectors, cameras, and light detection and ranging equipment (LiDAR) to collect traffic data, enabling artificial intelligence algorithms to make real-time adjustments that maximize traffic flow. The investment in these technologies is up to local governments. For example, in late 2023, the Ohio-Kentucky-Indiana Regional Council of Governments announced that they would upgrade 45 traffic signals in high-traffic areas in Butler County, Ohio