Testing the Puget Sound's land use model response to transportation strategies

Over the past few years the Puget Sound Regional Council (PSRC) has worked to advance its land use forecasting practices through the development and implementation of the UrbanSim land use model. More recently, PSRC has begun the integration of its transportation models with the land use models, employing feedback from each set of models to the others. This paper describes sensitivity testing conducted to better understand the correlation between the location choices of households and jobs to changes in land accessibility resulting from various different characterizations of a future transportation system. Through this integration a major advance in the agency's modeling approach has been achieved; thus providing a more robust method of assessing how land use and transportation systems co-evolve. A review of literature and practice yields an expectation of modest changes to land uses in response to incremental changes in transportation systems. The importance of many other factors besides accessibility is stressed in the literature. The application of the integrated models revealed an intuitively appealing and consistent relationship between accessibility and site values, but resulted in much more modest and difficult to interpret response in terms of changing locations of households and jobs. Taken together the findings appear generally consistent with theoretical expectations.