This paper reports progress on a study funded by the UK Engineering and Physical Sciences Research Council (ESPRC), to investigate "the design of optimal road pricing cordons". The authors are using the term cordon pricing to describe any system that charges vehicles for passing particular points in the network (which may or may not form easily identifiable cordons, in the traditional sense). The approach to design focuses primarily on identifying the best locations to levy charges and on specifying the optimal charge levels. The authors have set out to compare theoretical approaches, based on welfare economics, with practical ("judgmental") ones, drawing on the needs of policy-makers. The objective is to work towards a methodology that incorporates elements of both theory and practicality, to aid the definition of successful real-world road pricing systems. The paper is divided into three main sections. First, it outlines the theoretical approaches to cordon design, focusing primarily on the issue of location, as a detailed description of the approach to setting charge levels is already available elsewhere (Shepherd et al, 2001). Second, it provides an overview of the judgmental approaches adopted by transport planners, which include potentially important constraints on cordon design that may affect practical feasibility. Third, it presents results from a small modelling study that helps to illustrate the gap which currently exists between the judgmental and analytical streams and that hints at the potential of the latter to provide better solutions. A concluding section discusses the implications of the work to date and indicates the further research that is planned.
Abstract