In urbanised areas around the world, road pricing policies are considered more and more frequently, the aim often being to alleviate (some of the) external traffic-related costs. To assess the effects of a proposed road pricing measure, several evaluation measures can be used, coming from different disciplines, including economics, transportation science and transport geography. In this paper, we compare two types of evaluation measure that can be used to assess the effectiveness of road pricing measures: geographical accessibility measures and economic social surplus measures. We explore the possibilities of both types of measure in terms of evaluating road pricing effects from a theoretical perspective, as well as comparing their outcome measures for a research area in the Netherlands. By means of correlation analysis and spatial comparison of outcomes, we find that geographical accessibility measures, being simpler and easier to interpret than economic measures, offer a poor proxy of the outcomes of the economic evaluation measures and vice versa. Therefore, the decision whether to use economic surplus measures or geographical accessibility indicators to a large extent depends on the research goal. If the goal is to gain a thorough insight into the monetary gains/losses resulting from a policy measure, economic measures, such as the rule-of-half or the logsum measure, are preferable. However, if there are concrete questions about the changes in accessibility of certain types of activity locations, geographical indicators, such as the contour and potential measures, are more appropriate. The outcomes of such geographical measures, and especially those of the contour measures, are, however, sensitive to the spatial distribution of activity locations in the area under study and to the selection of the impedance parameter that has to be selected in advance to compute the effects. Therefore, if geographical indicators are to be used, it would be wise to use different sensitivity parameters. It is only then that a thorough insight can be gained into the (sensitivity of) geographical accessibility effects. © 2011 Taylor & Francis.
Tillema, T., Verhoef, E. T., van Wee, G. P., & van Amelsfort, D. (2011). Evaluating the effects of urban congestion pricing: Geographical accessibility versus social surplus. Transportation Planning & Technology, 34(7), 669-689. https://doi.org/10.1080/03081060.2011.602848