This paper examines the user equilibrium on a traffic corridor with several congested modes, a continuum of entry points and a single exit point. The approach taken is in the spirit of Beckmann et al. (1956) since it exploits the equivalence between the user equilibrium problem and a minimization problem. It is shown that this equivalence can be derived from a general economic principle due to Pigou (1950) that “If people are forced through taxes to pay the social costs of their actions, they act optimally.” The paper also demonstrates a set of conditions under which efficiency can be achieved by the application of only a gasoline tax on auto travel.