Co-introduction of charges on urban roads and motorways in metropolitan areas: a model-based investigation

摘要

This paper explores the relationship between charges on motorways and on other types of road. Itdraws on a model-based study of different pricing scenarios which was conducted within an EU-fundedinvestigation of differentiated infrastructure charges (the DIFFERENT project). The scenarios coveredstrategies ranging from full charging on all roads irrespective of category, on motorways only, onmotorway access roads, on urban roads only, and at cordons. A number of different charge levels weretested. The test results suggested that positive impacts and revenues are maximised by applying chargesto each link which reflect the contribution to externalities made by the marginal user of that link -irrespective of whether it is a motorway link or an urban link. However, when implementation costs aretaken into account, the best performing scheme was a cordon charge combined with a per-km charge foruse of motorways outside the cordon. Fixed per-km charges on motorways or on urban roads are muchless effective than charges which are differentiated to reflect congestion on individual links. Theintroduction of charges only on motorways produces little benefit and causes unwanted diversion to urbanroads, and although the introduction of a charge designed to protect the level of service enjoyed bystrategic motorway traffic succeeds in achieving that goal, it yields little revenue and has little overallimpact on delay or other externalities. The paper highlights the practical implications of these results andnotes that, although it is likely to be easier to gain political support for introducing charges on motorwaysthan on other types of road, the benefits from so doing are generally lower than can be obtained byintroducing charges on congested urban roads.