Urban Growth Modeling Approaches Discussion 1

Overview Planning Theory Meets Modeling Planning Theory Meets Modeling UrbanSim as an example of complex landuse/transportation modeling UrbanSim as an example of complex landuse/transportation modeling Theory Revisited: which capabilities under which circumstances? Theory Revisited: which capabilities under which circumstances?

The core assumptions that underlie a forecast … play a much larger role in determining the forecast outcomes than the sophistication of the tools used to prepare them Assumptions & Forecasts

Planning models should explicitly state their underlying assumptions concerning future trends and alternative policy choices. These assumptions should be easily modified and the effects of alternative assumptions and policy choices should be easily identified

Accuracy as a criterion …(A)ccuracy cannot be the proper criterion for evaluating forecasts. Instead, planning forecasts should be evaluated with respect to their ability to inform the policymaking process, facilitate community understanding, and prepare the public to deal with an uncertain future

Complicatedness Klosterman Klosterman “(M)odels will only be useful in a policy context if policy makers and the public understand and trust them.” “(M)odels will only be useful in a policy context if policy makers and the public understand and trust them.” “As a result, planners should attempt to develop models that are as simple—rather than as complex—as possible.” “As a result, planners should attempt to develop models that are as simple—rather than as complex—as possible.”

Waddell / UrbanSim Motivation Motivation “Metropolitan areas have come under intense pressure to respond to federal mandates to link planning of land use, transportation, and environmental quality” “Metropolitan areas have come under intense pressure to respond to federal mandates to link planning of land use, transportation, and environmental quality” “Requirements for improved and better integrated land use and transportation models have emerged not only in response to this federal legislation, but also from state growth management programs that promote closer linkage of land use and transportation planning” “Requirements for improved and better integrated land use and transportation models have emerged not only in response to this federal legislation, but also from state growth management programs that promote closer linkage of land use and transportation planning”

UrbanSim Data Organization

UrbanSim Model Structure

UrbanSim Interface Example

Concluding Discussion Points Is Simplicity in the eye of the beholder? Is Simplicity in the eye of the beholder? If it is important, shouldn’t it be measured and tested, not simply asserted? If it is important, shouldn’t it be measured and tested, not simply asserted? To what degree can or should planning model complexity be “hidden” from users To what degree can or should planning model complexity be “hidden” from users How important is it that transportation modeling be integrated with land use? How important is it that transportation modeling be integrated with land use? How can planning processes be organized to take advantage of models? How can planning processes be organized to take advantage of models? Who provides modeling assumptions? (what if not supported by empirical evidence?) Who provides modeling assumptions? (what if not supported by empirical evidence?) Must modeling be supported by a technical team, or is “hand’s on” modeling beneficial in and of itself? Must modeling be supported by a technical team, or is “hand’s on” modeling beneficial in and of itself? If technical modeling support is required close contact with end users? If technical modeling support is required close contact with end users?