In this paper, we take a political economy approach to study the introduction of urban congestion tolls, using a simple majority voting model. Making users pay for external congestion costs is for an economist an obvious reform, but successful introductions of externality pricing in transport are rare. The two exceptions are London and Stockholm that are characterized by two salient facts. First, the toll revenues were tied to improvements of public transport. Second, although a majority was against road pricing before it was actually introduced, a majority was in favor of the policy reform after its introduction. This paper constructs a model to explain these two aspects. Using a stylized model with car and public transport, we show that it is easier to obtain a majority when the toll revenues are used to subsidize public transport than when they are used for a tax refund. Furthermore, introducing idiosyncratic uncertainty for car substitution costs, we can explain the presence of a majority that is ex ante against road pricing and ex post in favor. The ex ante majority against road pricing also implies that there is no majority for organizing an experiment that would take away the individual uncertainty.

• Mot-clé
  TARIFICATION, RESEAU ROUTIER, POLITIQUE DES TRANSPORTS, TAXE, ANALYSE ECONOMIQUE, BELGIQUE