Fundamental Diagram of Traffic Flow

The Fundamental Diagram of Traffic Flow illustrates the relationship between vehicle speed, traffic density, and flow rate on a roadway. As traffic density increases, vehicle speed decreases, leading to a reduction in overall flow rate beyond a certain point. Initially, adding more cars improves flow, but after reaching a critical density, congestion causes speeds to drop sharply, and flow declines. Conversely, when traffic is light, cars move quickly but flow is low. This diagram helps traffic engineers understand and manage congestion by balancing vehicle flow and speed for optimal roadway performance.