Area-based equitable pricing strategies for multimodal urban networks with heterogeneous users

Equity issues among travellers are critical in congestion pricing. Failure to treat equity can lead to low acceptability towards pricing. In this paper, we develop congestion pricing schemes to improve both equity and traffic performance, for multimodal networks. We consider the equity issue by the existence of heterogeneous population, with respect to income level and value-of-time (VOT). An optimization framework is formulated for obtaining optimal toll schemes. We apply an aggregated network-level traffic flow model to reproduce congestion dynamics and mode choice behavior. The gain and loss for VOT-based user groups are investigated and discussed. We carry out simulation analysis over two pricing schemes: a unified toll and a VOT-based toll. In particular, we allow during the optimization process the VOT-based toll to obtain negative values for some users if it meets some system objectives. Our results confirm that significant differences in behavior and cost savings exist among groups, which justifies the need for a VOT-based pricing. It also demonstrates that properly-designed VOT-based tolls can improve the inequity in savings, e.g. users whose VOT values are lower may receive larger travel cost savings. Furthermore, a policy-oriented discussion on the design and implementation of the proposed equitable pricing schemes is provided.