In most dynamic traffic congestion models, congestion tolls must vary continuously over time to achieve the full optimum. This is also the case in Vickrey's (1969) 'bottleneck model'. To date, the closest approximations of this ideal in practice have so-called 'step tolls', in which the toll...

This paper discusses a number of issues that will become increasingly important nowthat the concept of marginal external cost pricing becomes more likely to be implementedas a policy strategy in transport in reality. The first part of the paper deals with thelong-run efficiency of marginal...