Properties of the Multiclass Traffic Network Equilibria Under a Tradable Credit Scheme

The multiclass network equilibrium problem is investigated under a tradable credit scheme. The social planner initially distributes a certain number of credits to all eligible travelers, charges a link-specific number of credits from travelers using that link, and allows for free trading of the credits among travelers. Travelers are assumed to be heterogeneous with a continuously distributed value of time (VOT). For a given tradable credit scheme and VOT distribution, the combined user equilibrium and credit market equilibrium problem is formulated into an infinite-dimensional variational inequality system, and the conditions for the uniqueness of the network flow pattern and the credit price at equilibrium are established. Manageable credit schemes that can decentralize a given target network flow pattern (e.g., the system optimum one) into a user equilibrium link flow pattern is proposed. With a numerical example, it is shown that an appropriate credit distribution rule may make every traveler better off. The stability of a desirable tradable credit scheme is also established, based on rigorous sensitivity analysis.