The theoretical approach to the analysis of road pricing benefits has been well rehearsed in the literature, however, it tends to be confined to one or two cases - either the choice between a congested route and an uncongested, but inferior, alternative, or the case where the delays imposed on other travellers are internalised by means of the charge. In practice, the type of urban road pricing which has the most chance of being implemented is the cordon charge, which is a much blunter instrument than is generally catered for in the theory. The paper examines the way in which benefits and disbenefits are likely to arise with cordon charging. The key categories of travel to be distinguished are: through traffic, travel wholly within are: through traffic, travel wholly within the cordon, travel crossing the cordon, travel wholly outside the cordon. The relative sizes of these groups is of crucial importance, and this, of course, will be determined by the location of the cordon. Each of the categories receives different combinations of time and money benefits and disbenefits, depending on the details of the cordon charge. Except at very low level of charge, the "ideal" case, where travellers are compensated for the charge by the time savings they experience, does not arise in practice. Drawing on the experience of the Department of Transport's London Congestion Charging Research Programme, the paper discusses the general principles of evaluation with particular reference to the spatial distribution.
Abstract