EVALUATING THE FUTURE: FORECASTING URBAN DEVELOPMENT USING THE
URBANSIM LAND USE MODEL IN EL PASO, TX. Quinn P. Korbulic
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- Background The El Paso MPO has invested in expanding their
modeling capabilities to include land use modeling. They chose to
explore UrbanSim. NMSU Spatial Applications & Research Center
Developed portions of initial UrbanSim database Conducted UrbanSim
Pilot Study.
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- Study Objectives Objectives Develop & Test UrbanSim
Database Run UrbanSim from 1997 to 2027 for two scenarios. Trend
(Business as Usual) Scenario Urban Growth Boundary Scenario Convert
the results to GIS format. Compare geographic variables from the
output of UrbanSim for the two scenarios.
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Add picture of EP MPO study area with the Pilot study area
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Study Area Area: 181.2 sq km Approximate Pop. 92,086 (2000
Census)
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UrbanSim UrbanSim Multi-agent microsimulation based behavioral
model. (Wadell, 2002) Reflects the individual choices of:
Households Businesses/employees Developers Governments and their
interaction with the real estate market over time.
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UrbanSim - Exogenous data, e.g. economic and population
forecasts - Travel Data, e.g. travel time to CBD, general travel
times -Demographic and Economic: Controls agents entering and
leaving the system. Agents entering the system are regulated by
control totals from exogenous data. - Households and Jobs: will
they relocate? Yes/No - Driven by relocation rates (exogenous data)
for jobs by employment sector and households by household type. -
Households, Jobs, and Development Projects: determines the
probability that an agent will choose a specific location. Monte
Carlo Simulation chooses the location for each agent. - Updates
land prices annually after all development and market activity are
completed.
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UrbanSim Data UrbanSim Datastore: 58 related tables. All data
necessary to run UrbanSim Primary Tables: Gridcells Jobs
Households
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Application of GIS The application of GIS played a critical
role in the development of the UrbanSim database: Tables: Connected
to space through GIS space alone isnt enough Attributes provide a
connection to what exists on the ground Otherwise, wed just have
location, not the what, when, why, or maybe even how.
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Gridcells Gridcells: 8054 150m x 150m 31 Attribute Fields e.g.
Slope Land Value Sqft by use zoning
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Jobs & Households Households: 30,595 Household Attributes
Persons Workers Age of Head Income Children Cars Jobs: 16,185 Jobs
Attributes Employment Sector Location
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UrbanSim and Land Use Policy The Development Constraints Table.
User defined development rules, i.e. zoning. Can take into account
any variable in the gridcells table, for example Plan type (zoning)
Building Square footage Proximity to Highways Etc Mandatory Fields
Min/Max Housing Units Min/Max Commercial Sqft Min/Max Industrial
Sqft
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Analysis Run UrbanSim Trend Run: 1997-2027 with no significant
changes to development constraints table. UGB Run 1997-2027 with
UGB introduced into the development constraints table.
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Modeling Uncertainty Essentially all models are wrong; the
practical question is how wrong do they have to be to not be
useful. George Box, University of Wisconsin.
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1997 Baseyear2027 Trend Forecast
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2027 UGB Forecast
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2027 Trend Total Density2027 UGB Total Density
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1997 TAZ Population2027 TAZ Population
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1997 TAZ Jobs2020 TAZ Jobs
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More Scenarios Floodzones: No Development Allowed. 1997-2027.
Using FEMA 100year Flood data, development was disallowed in
floodzones. Planned Development: Add 1000 housing units. 1997-2027.
To begin to accommodate for BRAC troop influx. Three Scenarios
Combined: 1997-2027 No Development in Floodzones Planned
Development Open Castner Range to Development
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1997 Trend2027 Floodzone
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2027 Planned Development1997 Trend
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2027 Three Scenarios
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Conclusions Overall, we found that the Urban Growth Boundary
did restrict new urban development. Also, it is a fairly simple
process to develop new land use scenarios and to run them one at a
time or together GIS played a non-trivial role in the development
of the database, and display of the results.