local government participated (Altshuler 1990; Higgins 1979, 1986). The mayors and council members who turned down Coleman's offer cited concern about the effect on low-income individuals, the reaction of users who had become accustomed to “free” highways, and adverse consequences for struggling downtown businesses.

The reasons for rejection of congestion pricing in the past have not changed. Any shift from the current system of financing and using the transportation system toward more marketlike mechanisms can be expected to engender public and political resistance (Wachs 1992). Concern that the poor would be less able than the middle class or the rich to pay congestion fees is often held up as an important political barrier to the acceptance of congestion pricing. (The unwillingness of some in the middle class to pay higher out-of-pocket expenses may be the more salient political barrier.) New road use charges of any sort are widely viewed as new taxes by a citizenry that holds the government in low esteem. In addition, some commercial interests in congested areas that might be subject to congestion pricing may be more worried about the possible short-term costs than the possible long-term benefits.

The political difficulties of congestion pricing have not gone away, but the forces in favor of congestion pricing have increased. Whereas local political leaders eschewed congestion pricing in the past, support is growing in some areas, particularly in California. Although congestion pricing proposals are proceeding in a small-scale, incremental fashion, that they are proceeding at all is a substantial change from this policy's fate when last seriously considered in the United States.

Volume 1 is an overview of the papers contained in Volume 2 and a summary of the committee's view of the potential for congestion pricing in the United States. Chapter 2 provides a brief overview of the theory and definition of congestion pricing, experience abroad, and current proposals for the United States. Chapter 3 summarizes the best available estimates of how congestion pricing might affect travel, different groups of motorists, air quality, energy, and urban form. Chapter 4 provides an overview of the administrative and political barriers to congestion pricing and how they might be overcome. The design of congestion pricing pilot projects and importance of evaluating any proposals that might be implemented are