Congestion pricing policies: Design and assessment for the city of Rome, Italy

Abstract

Congestion pricing is classified as a transportation demand management measure adopted to reduce impacts modern cities are suffering in terms of traffic congestion, road accidents and air and noise pollution. Such a measure allows linking road transport externalities directly to travelers producing them. The definition of proper tolling schemes enables this measure to act on demand short-term choices, forcing travellers to shift towards low impact road itineries (route diversion) and sustainable transport systems (modal diversion).This paper presents key findings in the design of pricing policies to a specific real size and complex case (city of Rome, Italy) addressing overall transport performances (on the multimodal network) and impacts (affecting the entire community), in a demand elastic context. Main contribution derives from equity matters dealt with in the impact assessment of pricing policies, so filling a gap not extensively studied in this field. Specifically, different tolling schemes have been defined from a quantitative (toll level) and spatial (city zones where pricing is implemented) viewpoint in order to guarantee equity aspects in the application of the measure: affected road users are limited to those travelling in city zones where the mass public transport network (metro and rail) is available; besides, the toll amount is related to the level of accessibility to public transport (whether only in origin/destination of the trip or in both).Results, evaluated adopting a simulation-based approach, are consistent with those obtained in other real world cases, and highlight that the adoption of a proper pricing policy in the city of Rome guarantees a demand diversion towards sustainable transport modes up to 25% for those zones directly involved by the pricing implementation; promising benefits have been observed even in a wider area, entire Province of Rome, not directly affected by the measure, in terms of reduction both of road users (up to 6%) and congestion costs (about 2%).