applications may be the only way this policy can be tested in the United States.

Whether congestion pricing will prove politically feasible in more than one or two places remains to be seen. Public and political concerns about fairness and motorist resistance to direct charges for highway use continue to be significant obstacles. The uses of the substantial revenues that congestion pricing can generate provide an opportunity to improve the efficiency of the transportation system, ameliorate the negative impact on adversely affected groups, and result in a net benefit for society. Some individuals would still be hurt, however, and whether they would be more motivated to resist congestion pricing than the majority who would benefit will be demonstrated only in actual practice.

Assuming that these early congestion pricing projects are implemented, careful and extensive evaluation is essential. These projects will remain controversial. The quality of the debates about these efforts would be substantially enhanced by reliable information about how traffic flows change, by careful analyses of winners and losers, and by survey research regarding motorist perceptions before and after the change. The early congestion pricing projects are not likely to provide substantial new insight into their potential for relieving regional air pollution and saving energy, but they will provide unique opportunities to learn about motorist sensitivity to price changes, how different groups and individuals are affected, and the political sensitivity to pricing as a transportation policy option. The earliest congestion pricing project to be implemented will be a private toll road in Southern California; this is not an ISTEA congestion pricing pilot project and is not eligible for the extensive evaluation funding permitted for pilot projects. The national interest, however, is sufficient to warrant a substantial federal investment in evaluation of any congestion pricing project. Congestion pricing has the potential to be a useful way to significantly reduce traffic congestion. It is a policy facing substantial political and administrative challenges; overcoming these challenges would be aided with the help of reliable information about the full range of issues surrounding it.