speed-density relationship

The speed-density relationship describes how vehicle speed decreases as the number of cars on a road increases. When traffic is light, cars can travel faster because there’s more space between them. As more cars enter the road, congestion builds, making it harder to maintain high speeds. Eventually, when the road is very crowded, vehicles move slowly or come to a stop. Essentially, there’s an inverse relationship: higher vehicle density leads to lower average speed, impacting traffic flow efficiency. This helps transportation planners design better traffic systems and manage congestion.