Optimal nonlinear distance toll for cordon-based congestion pricing considering equity issue

In order to address the optimal distance toll design problem for cordon-based congestion pricing incorporating the issue of equity, this paper presents a toll user equilibrium (TUE) model based on a transformed network with elastic demand, to evaluate any given toll charge function. A bi-level programming model is developed for determining the optimal toll levels, with the TUE being represented at the lower level. The upper level optimizes the total equity level over the transport network, represented by the Gini coefficient, where a constraint is imposed to the total travel impedance of each OD pair after the levy. A genetic algorithm (GA) is implemented to solve the bi-level model, which is verified by a numerical example.