Beyond Uncertainty: Modeling Transportation, Land Use, and Air Quality in Planning

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Beyond Uncertainty: Modeling Transportation, Land Use, and Air Quality in Planning


Concerned citizens across the United States are increasingly asking officials about the effects of proposed new highways and their alternatives, such as transit and road pricing, on how their communities will grow, the air their children will breathe, and the amount of time they will have to spend in traffic commuting to work. It is widely acknowledged, however, that the models used to assess these effects have limited accuracy and sensitivity to alternatives to highway expansion. This study attempts to move beyond the issues of uncertainty in models used to forecast the travel, land use, and air quality effects of transportation projects and policies by (1) reviewing the literature on error and uncertainty in travel and land use models to understand key sources, likely confidence bounds, and potential biases; (2) conducting interviews with modeling experts to gain insight into how uncertain models may be improved and better applied in transportation studies; and (3) presenting a series of cases studies that illustrate innovative and, possibly, more credible approaches to modeling given different study objectives, model capability, and knowledge of model uncertainty.



Caroline Rodier is an assistant research engineer at the University of California, Berkeley. Her research interests include transportation policy and planning; land use and travel demand modeling; the behavior effects of new technology applications in transportation; and elderly travel behavior. Some of her current projects include analyses of modeling uncertainty in the context of environmental impact and air quality conformity processes; a behavioral evaluation of a transit-based smart parking field test; a feasibility analysis of a virtual compliance station for commercial vehicles; and social marketing interventions to enhance older traveler mobility. She has authored 16 journal articles, 29 proceedings articles, and 22 research reports.

October 2007
Air quality
Land use models
Land use planning
Policy analysis
Urban planning



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