This paper shows that the iterative optimization-equilibrium algorithm used to solve the continuous network design problem does not solve the original Abdulaal-LeBlanc normative network design model, but rather is an exact and efficient solution procedure for a descriptive model in which the planner and the network users compete in a Cournot-Nash setting. The existence of a solution to this descriptive model is proved, numerical results which illustrate convergence and efficiency of the algorithm are given, and suggestions for future research are made.