ABSTRACT
Transportation use results in important external costs. In the case of road transportation these mainly consist of congestion, environmental costs (related to air pollution, climate change and noise) and accident costs. Several measures have been proposed to tackle these externalities. They include regulation, infrastructure measures and economic instruments. The choice among these instruments, or packages of instruments, depends not only on their relative efficiency but also on their equity impacts. Most studies consider only the efficiency of transportation instruments. However, a sound understanding of the equity impacts of transportation policies is crucial. In general, governments do not only care about efficiency, but also about the distribution of welfare between different groups. Moreover, the equity impacts are an important determinant of the political acceptability of transportation reforms. Any major pricing or taxation reform will be acceptable only if it is welfare increasing or welfare neutral for a sufficiently large proportion of the voters. This is the essence of the economic approach to acceptability. A necessary condition for voters to accept reform is that their utility is not reduced. For some types of reform, the utility impacts on voters will be unequally distributed which makes the reform more difficult to accept.
