Route navigation by state-contingent road pricing

In this paper, network equilibria under state-dependently varying road pricing are analyzed. Our focus is upon the informational role of road prices; they may convey information about road conditions to drivers, if they are announced to drivers before they decide their route choice. To investigate the impact of state-dependent road pricing upon drivers' welfare, we formulate network equilibrium models based upon three different traffic assignment principles: (1) network user equilibrium assignment, (2) total expected utility maximization assignment and (3) network user equilibrium assignment with toll systems. It is then shown that provision of route guidance information does not necessarily improve drivers' welfare in the Pareto sense. It is also proven that the improvement of drivers' welfare can be always assured by variable road pricing systems with zero-balanced constraints, while the Pareto improvement of network equilibria can be achieved by levying Pigouvian variable road pricing. The paper is concluded by illustrating some numerical examples.