Traffic Flow And Capacity

The design of highways, runways, ports or any transportation facility is guided by knowledge and theory of the traffic streams they serve. A facility’s scale, its geometry and its control measures are selected to affect certain properties of its traffic, such as the travel delay, the separation between vehicles, etc. In the case of highway traffic, the emphasis of this chapter, these are usually properties that are collected from, or averaged over, some number of vehicles. This is because the behavior of one driver differs from that of another, sometimes in complicated or even unexpected ways, and the traffic engineer typically seeks properties that are reproducible or predictable; i.e., properties that are not sensitive to driver variations.