Traffic management through link tolls - An approach utilizing side constrained traffic equilibrium models

Artikel i vetenskaplig tidskrift, 1997

We propose a systematic means for achieving a set of overall traffic management or planning goals with respect to the performance of the traffic network through the use of link tolls. The primary goals are defined by a set of link flow restrictions. The tolls that achieve these goals are obtained by solving a generalization of the classical user equilibrium model which includes a set of side constraints on the link flows. The set of toll prices obtained is not necessarily unique; this fact enables the traffic planner to choose a toll scheme which satisfies exogenous constraints and which may optimize a secondary goal, such as with respect to the toll itself. The overall model is derived as a special case of a mathematical program with equilibrium constraints (MPEC) describing a Stackelberg game involving the traffic manager and the users of the network. The model is shown to yield valuable information also in the case where the management goals and exogenous toll constraints are inconsistent with each other or with the underlying network. We give several examples of possible applications of the model, including the achievement of a system optimal flow and the derivation of actions for making public transport more attractive, and propose a conceptual algorithm for solving it. The paper is hoped to provoke continued research in both theoretical and applied directions.