This chapter has overviewed the major developments in the mathematical economic modeling
of transportation and has also identified some of the significant connections between
transportation networks and other network applications. Such relevant behavioral principles
as user-optimization versus system-optimization were discussed and illustrated through the
Braess paradox. Increasingly complex and general transportation network models were described,
beginning with the fixed demand transportation network model (both user-optimized
and system-optimized versions) with separable user link cost functions through the elastic
demand transportation network equilibrium model with asymmetric user link cost and travel
disutility functions. Discussions of optimization theory, variational inequality theory, andprojected dynamical systems theory for network dynamics were also presented, as relevant to
transportation network problems. In addition, a transportation network efficiency measure
was reviewed, along with the importance identification of network components, that is, the
nodes and links. Throughout this chapter examples were provided for illustrative purposes.
Finally, related applications to the Internet, supply chains, as well as electric power generation
and distribution networks and financial networks were noted. This chapter vividly
demonstrates the essential importance of transportation networks and their rigorous study
to both theoretical advances and practice.