Nonlinear, Secondary Impacts of Large Urban-Edge Developments as Evidence of Path Dependency in an Integrated Land Use and Transportation Model

The practice of integrated land use and transportation modeling has improved in the past decade. Use of these models has steadily increased among U.S. metropolitan planning organizations and recently among state departments of transportation. This paper examines the secondary growth impacts of large, urban-edge developments in an integrated model to determine the existence and characteristics of induced land development (also called path dependency in the modeled land development process). The Sacramento, California, MEPLAN model is used to simulate the impact of large, urban-edge, basic sector developments on overall and industry-specific employment in the subject zone over a modeled 25-year period. Four types of basic sector development are considered: office and service, industrial and manufacturing, retail, and government. Ten sizes of each type were modeled, and each simulated development shares a common location and year of construction or occupancy. The study found that secondary employment draw was substantial for all sizes and types of projects, certain industries produced much larger secondary draws than did others, secondary growth increased with the size of the development and continued to have an impact in all future modeled years, and the relationship between initial development size and secondary growth is nonlinear in each development type. This significant, persistent secondary draw suggests that this model manifests a key characteristic of path dependency in the location and building decisions in the model (i.e., a relatively small shift in basic employment can create new development “paths”). These findings yield recommendations for incorporating this work into integrated modeling research and practice.