As the director of a major university transportation research center, I am honored and pleased to have been included in this program in which we are exploring the contributions that research can make to the refocusing of transportation knowledge and planning practice. It is actually quite rare that line agencies or federal funding programs try to assess what research can provide and what it cannot do. But it is important to think strategically about research just as it is to think about planning and policy matters that hopefully are informed and improved by good research.   

It is probably useful to conceive of the world of research as being analogous to a market like any other market for goods and services. We have suppliers who offer goods and services for sale, research studies can be thought of as a product like any other commodity of service; and those of us in universities, think tanks, and consulting firms want to sell our research services just like other purveyors of good things.

Transportation planners are increasingly adopting policies aimed at changing travel choices made by citizens. Rather than trying to solve transportation problems by building highways and transit routes, transportation demand management relies on incentives and disincentives to promote carpooling, vanpooling, transit use, and changed work hours. These approaches attempt to accommodate travel demand by more efficiently utilizing existing facilities. Although many argue that transportation behavior cannot be changed, this review demonstrates that many years of behavioral science research on travel show otherwise. Commuters respond to differences in travel time and travel cost and to changes in work hours and other attributes of travel in systematic ways that are quite predictable. As a consequence, travel demand management is a promising approach to regional transportation planning.

Just as the Eiffel Tower is the symbol of Paris, and the Statue of Liberty is the symbol of New York, it can be said that the freeway is an internationally recognized symbol of California. The California transportation system was not too long ago the envy of the world, yet there is today a serious question as to whether or not our state is in a leadership position with respect to the provision of mobility to its citizens.

Forty years ago, Governor Pat Brown and most members of the state legislature believed that transportation infrastructure investments were fundamental to economic growth and that large commitments of public funds for the construction of a transportation network would pay ample dividends over many decades in the form of growth in population, commerce, tourism, and tax revenues. These views enjoyed broad public support. The aggressiveness with which leaders in the fifties built a state highway system can today be criticized by environmentalists and preservationists, but it was monumental and their projections of growth and change have over time been proven to have been largely correct. The shared sense of direction and commitment that characterized our state during the freeway building days, and the partnership between federal and state governments that funded our highway system is long since gone. In place of unity and commitment transportation policy making is today characterized by timidity and indecision. With our state highway program stalled, California’s public transit program is also falling far short of what is needed to provide mobility to a growing number of inner-city transit dependent people. As we look forward to a new century, we must question whether our transportation program is sufficient to serve the population growth we expect or to sustain the economic growth that we hope for.

Winston Churchill once wrote an insightful analysis of architecture (1). According to Churchill, we first designed buildings to accommodate our behavior and our social and cultural patterns as we understood them. But our understanding of these things was imperfect, and different architects interpreted them differently. Moreover, buildings reflected limitations posed by their sites, by their budgets, and by the building materials used. Over time, the buildings we constructed shaped our behavior and became the determinants of new social and cultural patterns.  

American attitudes toward transportation planning have recently undergone significant change. For three decades after the end of World War II, public policy emphasized the construction of new highway and transit facilities in order to remove the backlog of needs which resulted from the combined effects of depression, a war economy continued urban growth, and accelerating automobile ownership. For the most part, there was consensus among transportation policymakers that their primary goal was to accommodate growth by constructing facilities which would have adequate capacity to handle future demand. It was understood that land use patterns and economic development were the sources of traffic, yet there was general agreement that transportation policy should aim to accommodate forecast land use and economic growth rather than to regulate them in order to control traffic.

Traffic congestion is a vexing problem felt by residents of most urban areas. Despite centuries of effort and billions of dollars worth of public spending to alleviate congestion, the problem appears to be getting worse. Between 1980 and 1999, vehicle-miles of travel on U.S. roadways grew by 76 percent, while lane miles increased by only 3 percent. Average daily vehicular volumes on urban interstates rose by 43 percent between 1985 and 1999, from 10.331 million to 14.757 million. In a study of 68 urban areas published in 2001, the Texas Transportation Institute reported that the percentage of daily travel taking place during congested periods increased from 32 percent in 1982 to 45 percent in 1999; typical motorists faced seven hours per day of congested roadways in 1999 compared with five hours in 1982. According to the Federal Highway Administration, road delays (defined as travel time in excess of that at free flow conditions) increased by 8.5 percent between 1993 and 1997. Congestion also pollutes the air and wastes precious fuel.

Transportation planners are increasingly adopting policies aimed at changing travel choices made by citizens. Rather than trying to solve transportation problems by building highways and transit routes, "transportation demand management" relies on incentives and disincentives to promote carpooling, vanpooling, transit use and changed work hours. These approaches attempt to accommodate travel demand by more efficiently utilizing existing facilities. While many argue that transportation behavior cannot be changed, this review demonstrates that many years of behavioral science research on travel show otherwise. Commuters respond to differences in travel time and travel cost, to changes in work hours and other attributes of travel in systematic ways which are quite predictable. As a consequence, travel demand management is a promising approach to regional transportation planning.

Transportation investments have in the past among society’s most important contributors to environmental improvement, but today transportation programs and projects are more often of concern as sources of major environmental problems. Over the past 30 years, since the enactment of the National Environmental Protection Act (NEPA) and the first Clean Air Act amendments, the relationship between transportation planning and environmental policy making has continuously become more complex and problematic.