What happens to speed according to Greenshield's Model as density approaches zero?

In Greenshield's model of traffic flow, the relationship between speed, density, and flow is analyzed to understand traffic behavior. According to this model, as vehicle density approaches zero, it indicates a state where vehicles are very sparse on the road.

In this scenario, vehicles are not closely packed together, which allows them to travel at or near their maximum speed without the constraints of congestion. Therefore, the correct interpretation is that as density decreases towards zero, speed will approach a constant value close to the maximum speed supported by the road conditions, rather than decreasing to zero.

The correct understanding is that at densities near zero, vehicles can maintain high speeds, respectively aligning with the ideal conditions of free-flowing traffic. Thus, speed does not decrease to zero but instead approaches that maximum limit established by road design, capabilities, and environmental conditions.