Innovations in Travel Demand Modeling, Volume 1: Session Summaries (2008)

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24 BREAKOUT SESSION Land Use Forecast J. Douglas Hunt, University of Calgary, Canada Paul Waddell, University of Washington Becky Knudson, Oregon Department of Transportation THE CASE FOR INTEGRATED LAND USE–TRANSPORT MODELING J. Douglas Hunt Douglas Hunt discussed the use of integrated land use–transport models. He defined different elements associated with integrated land use–transport models, described examples of feedback forms, provided a ratio- nale for integrated land use–transport models, and described potential applications of integrated land use–transport models. Douglas covered the following points in his presentation. • Understanding the different definitions associated with the application of integrated land use–transport mod- els is important. The transportation system is the interac- tion between supply and demand that acts on price signals. A spatial activity system is supply meeting the demands of that system. How to characterize the land use system is an important consideration. Land use system is probably not the appropriate term, but was acceptable when invento- ries were measured by square footages. Land use system is a loose and inappropriate term for spatial economic sys- tems. Line- process modeling addresses transportation components in a sequential manner, such as the traditional four- step model, whereas land use–transport interaction modeling incorporates critical feedbacks. • Feedback is a key element of land use–transport interaction modeling. A number of different feedback forms may be used. Location accessibilities, which involve using log- sums to express relative accessibility, represent one approach. Other feedback forms focus on interchange disutilities and integrated models. Transport costs, with price signal changes influencing activities, represent another possible approach. • Modeling tasks are best described as forecasting to support facility design. Policy analysis is supported by modeling how future changes arise in response to differing assumptions. Modeling imposes discipline and there are a variety of legal reasons for justifying the use of integrated land use–transport models. Essentially, land use–transport models provide a more complete representation of the real world, a more holistic or organic perspective, and thus avoid the philosophy of line- process modeling. • Integrated land use–transport models can be used for many different types of studies and have numerous benefits. Integrated land use–transport models can sup- port policy studies, planning assessments, and design analyses. Land use–transport models provide a more complete representation of the real world, which can enhance future planning and decision making. Examples of instances in which integrated land use–transport mod- els were not used raise some concerns regarding the con- clusions that were derived. CHALLENGES IN INTEGRATED LAND USE AND TRANSPORTATION MODELING: LESSONS FROM URBANSIM EXPERIENCE Paul Waddell Paul Waddell discussed the use of the UrbanSim integrated land use model. He described some of the factors that