The present work analyses and classifies the most relevant external costs produced by urban transportation and relates these to the various forms of internalisation through the payment of a tariff. The objective is to confront the theoretical suggestions and the philosophy adopted in the practical implementations in various countries. We conclude that the present technological level available allows both a strong correlation between instruments and objectives as well as a substantial flexibility of the tariff charged so to overcome some of the informational gap concerning the estimation of external costs. The limited application of these systems may probably be due to their distributional effects.
