It was in the domain of such transportation network equilibrium problems that the theory
of finite-dimensional variational inequalities realized its earliest success, beginning with the
contributions of Smith (1979) and Dafermos (1980). For an introduction to the subject, as
well as applications ranging from transportation network and spatial price equilibrium problems
to financial equilibrium problems, see the book by Nagurney (1999). Below we present
variational inequality formulations of both fixed demand and elastic demand transportation
network equilibrium problems.