1 Solving Congestion Tollpricing

Recently a methodology for traac networks has been developed which extracts congestion toll sets such that the tolled user equilibrium is system optimal. Properties of toll sets, such as convexity, are investigated, as well as relationships with other problems. For a given toll set, various objectives can be deened and optimized with respect to the tolls. Examples include minimizing the total tolls collected, minimizing the number of toll booths and constraining net tolls collected to be zero. We illustrate with an example and report on our computational experience with the Stockholm network. 1.1 INTRODUCTION Congestion toll pricing addresses the classic traac assignment problem for which Wardrop enunciated two principles of traac ow: user-optimal behav-ioral hypothesis and the notion and system-optimality. (See 7] for a recent review of the traac assignment problem and 12] for a recent volume of papers on road pricing.) The traditional objective of congestion pricing has been to determine link tolls which will cause the solution of the tolled user-optimal problem to be optimal for the untolled system problem 1]. In most of the lit