Congestion pricing has long been advocated as a means of increasing the efficiency of use of congested roads. This paper makes use of an economic model of a congested road network in a stationary state to investigate two objections to road congestion pricing: it may be inequitable for the road users affected, and it generates perverse incentives for governments. The paper investigates how different congestion delay functions and different mixes of traffic affect these objections. The following conclusions are drawn: (1) The effects of road congestion pricing are sensitive to the congestion cost function. Congestion pricing is a better buy for bottlenecks than for linear speed-throughput relationships; (2) The scale of unwanted redistribution from road users to the rest of the community induced by optimal pricing depends on the congestion cost function. It is zero for bottlenecks with homogeneous traffic, but may be large relative to the net gain in benefit for linear speed-throughput relationships; (3) In mixed traffic, if there is a correlation between the value of time of traffic units and the value of the journeys they are making, congestion pricing is a better buy than otherwise. Public transport and other high-occupancy vehicles (HOV) would benefit; (4) Nevertheless, it is possible to help high-occupancy vehicles in other ways, such as by the selective allocation of road space, and (5) Governments would have a strong incentive to depart from economic efficiency in setting prices, and substitute a revenue target. There would be a strong case for an independent body to regulate prices. (Author/publisher).
Samenvatting