Traffic Maximization. The purpose is to assess the maximal demand that a network can support considering its transport supply. Traffic maximization estimates the operational capacity of networks, that is, what amount of traffic they can handle under ideal conditions. The above graph (1) is the estimated optimal demand a network can support since once that level of demand is exceeded, travel time increases exponentially due to congestion. Traffic maximization usually concerns engineers, especially for the simulation of the optimal capacity of a transport system. It is also important to the planning of new transport systems.
Costs Minimization. The purpose is to assign on a network a known demand in order to convey minimal costs. On the above graph (2) represents a traffic assignment (paths between origins and destinations) that minimizes transportation costs. Cost minimization is particularly of concern to operators of transport assets (e.g. fleets of vehicles), since they are concerned about how a service can be offered to satisfy demand, and this at a minimal cost.