The author takes issue with a number of aspects of the paper by Evans (1992) (see IRRD 854491) on the social implications of a congestion-pricing system. Hills argues that: a) congestion is more complex than Evans' assumptions allow even at strategic level; b) all three speed/flow relationships explored are conceptually flawed; c) definitions of capacity and throughput are inconsistent and the treatment of time is perverse; and d) mis-specification of both demand and supply arises from the use of a flow-based measure instead of a trips-based one. Each issue is discussed in detail. The paper includes a reply to these comments by Evans covering the standard economic model of road congestion pricing, stationarity and time dependence, networks and backward-bending speed-flow and congestion cost flow functions.
Abstract