tional consequences and the use of the revenues earned. Discussed in this section are several other issues that need careful consideration: allowing sufficient time for a proposal to develop political acceptance, setting an appropriate price, and providing alternative routes or modes of transport for those who prefer not to pay a congestion fee.

Congestion pricing has gained currency only in a few places, and even in these cases the process of gaining political acceptance has been quite slow and conditioned by almost unique circumstances. Interest in California has surely been fostered by the fiscal restrictions that voters have placed on state and local government spending, the continued rapid growth in population and automobile travel, and the stringent requirements of the California Clean Air Act. In the San Francisco Bay Area, congestion pricing has also been furthered by broad public concern about the environment and by the sophisticated advocacy of a business-sponsored organization dedicated to resolving regional issues in the Bay Area (Dittmar, Vol. 2). Even with these conditions influencing adoption of congestion pricing, the Bay Area congestion pricing proposal was some years in the making (and at the time of this writing requires state enabling legislation to raise the toll). In San Diego, interest in congestion pricing was fueled by accelerated growth in traffic congestion over the last few years, the leadership of local elected officials, and the general acceptance of a philosophy of charging the user directly for the cost he or she imposes on others (Duve, Vol. 2). Even so, acceptance of the concept of congestion pricing emerged over a considerable period of time.

In contrast, an effort to build consensus for a congestion pricing proposal for Manhattan during the late 1980s was summarily dismissed by the public and by some downtown commercial interests (Altshuler 1990; Zupan, Vol. 2). These cases suggest that interest in congestion pricing— driven by concerns about congestion and the environment—will emerge in a few places, but sufficient public and political acceptance to allow it to go forward will occur slowly, if at all. The congestion pricing pilot projects allowed under the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) may be developed at any time during the 6-year authorization period, but the time frames for development and implementation of proposals to meet the first and second rounds of solicitations