The Social Cost of Road Congestion in Ile-de-France Region (and France): Empirical Evidences from the Paris Ring-Road

The aim of this article was to assess specific problems concerning traffic congestion access to the city of Paris. First, we attempted to evaluate the evolution of the congestion cost for the Paris Ring-Road (PRR), the major urban highway surrounding the French capital, during the period from 2000-2007. A speed-density methodology was implemented which enabled us to differentiate the external costs of road congestion between speed-classes of 5 km/h. These results were useful to subsequently propose the order of magnitude of time losses at national and regional scales, as well as marginal pricing schemes which could potentially be used in order to correct road congestion externality on the PRR. Our empirical investigation concluded that, in 2007, the PRR was more costly for central Paris area (130 M€) compared to that of seven years earlier (117 M€). The deterioration of traffic conditions, symbolized by the mean speed fall (- 5.2 %), dominates the infrastructure least used (- 2.2 %). Based on these figures, the social cost of road congestion is thought to reach about 0.2 % of the French GDP. This ratio becomes three times higher once reported on a regional scale and underlines that road congestion is an important issue for Ile-de-France. Finally, despite their analytical limitations, the proposed taxes clearly illustrate the challenges related to road-pricing strategies