Optimal Toll Rate and Expansion of Urban Expressway

Some extension is made of the previous papers of the same title in order to investigate (1) what aspect consumers' surplus has according to the characteristics of inverse demand curve and (2) where the maximum consumers' surplus is reached in an equilibrium of toll revenues and cost. As for (1) three kinds of inverse demand curves are assumed in general form. The marginal consumers' surplus to expansion of expressway network is proved to be of definite sign (positive or negative) or equal to zero according to each curve assumed. For each of curves, the region where consumers' surplus finds its maximum is also shown on the expressway users ~ network expansion plane.