Types of Traffic Costs

• The global cost is the sum of transport costs for every link of a network considering the demand.
• The average cost expresses the transport cost per unit in a network considering the demand (global cost/load). It often varies with the demand.
• The marginal cost expresses costs incurred to transport a supplementary unit in a network considering an existing demand. The more a network is congested, the higher the marginal cost (in the case of non-linear cost functions such as the one above).