September 26, 2002

UrbanSim: Shaping metropolitan futures

  • UW simulator integrates transportation, land use and public policy
    University of Washington

    Gov. Mike Leavitt of Utah promoted the construction of a new north-south highway as a solution to the chronic traffic congestion on the only north-south corridor in the Salt Lake City region.

    The new highway would be named Legacy Highway. Unfortunately for the governor, environmentalists have dubbed it “Lunacy Highway” since it would run through sensitive wetlands and open up much of the remaining open space west of the urban area to new suburban development.

    The Sierra Club took the state of Utah and the U.S. Department of Transportation to court. This kind of conflict has, of course, become commonplace throughout America, where no community seems to escape prolonged struggles over transportation and development. But the way the Utah highway battle is playing out — featuring attempts at genuine compromise and with the assistance of the University of Washington’s UrbanSim project — offers some hope that American communities can find better ways to make decisions.

    Highway construction fallout

    The Utah lawsuit is reminiscent of similar suits in the San Francisco Bay Area and Chicago in recent years that have sought to reassess the impacts of highway construction on the environment and on induced demand for travel. The question is a major one in every large metropolitan area grappling with congestion and pondering multi-billion dollar expansions of highway and/or transit systems.

    Environmentalists argue that expansion will stimulate suburban sprawl, devouring open space in the process, and will encourage additional travel that overwhelms the new roadway capacity with more discretionary trips. Transit advocates argue that more highway construction adds to an already distorted pricing structure by subsidizing travel in single-occupancy vehicles and making buses or light rail less competitive.

    The answers to problems such as these are partly technical issues of sorting out the combined effects of projects on urban development and travel behavior. They are also partly political issues of sorting out the relative weight to be given to underlying community values that are in conflict, such as the value of individual freedom we tend to associate with driving a car on uncongested roads, or the value of preserving open space, or the value of accommodating the less affluent members of our communities with affordable housing and transportation options, or the value of individual property rights, or the value of local control of land use decisions, or the value of minimal taxation and governmental intervention.

    In community after community, these issues are pitting groups against each other and more often than not leading to political gridlock with no winners and many losers.

    In Utah, community involvement in a long-term visioning effort for land use and transportation issues, known as Envision Utah, has over the past few years become a nationally renowned prototype for collaborative visioning. It brought together stakeholders from all segments of the community to come to some agreement about the region’s future.

    Although the process had its limitations, it was in fact a remarkable accomplishment that a cross-section of the community could achieve consensus on a broad vision for the future of the region that looked much more diverse than the region does today. The preferred scenario would substantially increase housing and transportation options and would preserve substantial agricultural and resource lands and reduce infrastructure costs, compared to current trends.


    In spite of the exemplary effort to work collaboratively, the story is not over for Utah. The Sierra Club lawsuit, after a setback in its initial hearing, was appealed, and was settled in June.

    The settlement included an injunction to halt construction on Legacy Highway, for which the state must continue to pay the highway construction contractor approximately $100,000 per day until the terms of the settlement are achieved.

    It also included a memorandum of understanding that the regional planning agency, the Wasatch Front Regional Council, would use UrbanSim, a new computer simulation model developed by researchers at the University of Washington to assess the effects of major transportation investments such as Legacy Highway on urban development and travel.

    So how, you might ask, did ivory-tower academics come to be involved in developing technology that is being cited as a basis for settlement of a lawsuit over a major highway investment?

    UW researchers have developed the UrbanSim system over the past few years with the intention of making it useful in analyzing the interactions between transportation investments, land use and the environment, and in mediating conflicts that abound over these topics. It has now been applied in Eugene-Springfield, Ore., Honolulu and Salt Lake City, and preparations are under way to apply it in the Puget Sound area.

    The research has recently attracted more than $5 million in new investment from the National Science Foundation, focusing on bringing interdisciplinary research to bear on real-world problems. It represents a major initiative to take on research that is relevant to the broader community, and provides an opportunity for researchers in academic disciplines ranging from civil engineering to urban planning, and from computer science to public policy, to come together to make a difference in addressing some of the most vexing and complex problems of our times.

    Hurdles to overcome

    The stakes are high in Utah, but are not fundamentally different in scope or cost than the debates within the Puget Sound area over expansion of Interstate 405, replacing the Alaskan Way Viaduct and the Evergreen Point Bridge, building Sound Transit and the monorail.

    Washington’s Growth Management Act provides valuable guidance about principles of managing growth and providing for infrastructure to accommodate growth, but leaves implementation decisions to the local level, where conflicts over values continue to make consensus and progress difficult.

    These are complex problems, but increasingly, the mood of the voting public seems to have tilted towards solutions that are singular and simplistic in their focus, such as building a particular transportation project or limiting taxes.

    In Washington, as in other states, initiatives have made it difficult to undertake careful analysis of alternatives and to consider the indirect effects and interactions among various public choices. The question that needs to be asked is whether we can find alternative ways of deciding about major public investments that allow residents to articulate their values and preferences, that generate many alternatives for consideration and analyze the direct and indirect effects of these alternatives.

    Perhaps this is a good time to begin to explore partnerships between academia and the public sector to find better ways to address these chronic problems.

    Paul Waddell is an associate professor at the UWs Daniel J. Evans School of Public Affairs and director of the Interdisciplinary Ph.D. Program in Urban Design and Planning.

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