Aspetti economici del road-pricing

This paper aims at presenting a discussion of the economic theory of road pricing, as a preliminary both of evaluations of applied schemes and of comparison with alternative policy instruments. Environment and road capacity are scarce resources: the citizen-consumer enjoys freedom of choice but users may not pay an efficient price, all the more so when user-generated negative externalities are taken into account. The social marginal cost of using road capacity is the sum of private costs paid by the user (fuel, depreciation, time) and of social costs paid by other users (congestion delays), public authorities (road maintenance) and society at large (pollution). Traffic congestion, and associated pollution, is a typical urban phenomenon: in fact, although private costs are higher in congested areas (cities) than in uncongested areas (countryside), diseconomies are relatively even higher, so that traffic (congestion, pollution) is in excess of what would be socially optimal. The typical theoretical answer is to 'internalise externalities': consumer still choose according to their willingness-to-pay, but bear a cost related to the diseconomies they generate. The attempt to make the private user pay for social costs is justified on social efficiency grounds, in so far as it discourages movements producing a private benefit lower than the sum of private and social costs. Although the impact of road pricing appears on the demand side, it may guide longer-term decisions on the supply side. Paper contents are as follows: road pricing theory is presented; criticisms to it are discussed; complementary effects of uses of road pricing revenue are evaluated.