How do Traffic Signals Work (2019)

Traffic signals are a fundamental tool for managing intersections in urban areas, where multiple streams of traffic—vehicles, bikes, and pedestrians—must safely cross paths. Intersections represent a critical bottleneck for road capacity; increasing lanes or speed limits has minimal impact without improving intersection efficiency. Traffic engineers must balance numerous conflicting factors including safety, cost, traffic volume, and human behavior when designing intersections, while also maintaining standardized signals so drivers know what to expect at unfamiliar locations.