Puget Sound Regional Council

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Mark Simonson

Peter Caballero


What Is UrbanSim?

PSRC uses the UrbanSim model to develop projections of future population and employment for cities, counties, and other geographies. Planners can also use UrbanSim to create scenarios of what might happen if land use plans or highway projects are changed.

What Does UrbanSim Do?

  • Produces a growth projection for each year (currently out to 2040)
  • Predicts land development at the parcel level
  • Interacts with PSRC’s travel models so the impacts of land use on transportation, and vice-versa, can be modeled
  • Simulates the location decisions for each household and job in the region (known as micro-simulation)
  • Uses results from the Regional Macroeconomic Forecast as its control totals and predicts where in the region growth will likely go
  • Takes as an input how many housing units or square feet of building space can be built under existing comprehensive plans, including adjustments for environmentally-sensitive areas
  • How has land use forecasting changed at PSRC?
    • Land use forecasting at the PSRC has undergone significant changes. In 2003 work began on UrbanSim to replace the zone-based DRAM/EMPAL models that had been in use since the 1970’s. Developed by Dr. Paul Waddell, UrbanSim’s parcel-level structure offers multiple advantages over DRAM/EMPAL, including the ability to more accurately model land use plans and zoning restrictions, and the flexibility to sum up output to any geography compatible with parcels. UrbanSim was first used at PSRC in the 2009 to support the modeling work for Transportation 2040. UrbanSim’s first land use forecasts were released in July 2013 as the Land Use Baseline.
  • What’s new with UrbanSim?
    • After the first release of the Land Use Baseline, a Maintenance Release 1 (MR1) update followed in April 2014. Concurrent with the release, PSRC has prepared an UrbanSim model validation report that also addresses uncertainty present in land use forecasting by estimating confidence intervals associated with the year 2040 results. Currently, staff are working to improve and expand UrbanSim to support other analysis and modeling needs, including the agency’s new SoundCast activity-based travel model.

Puget Sound Regional Council • 1011 Western Ave, Suite 500 • Seattle, WA 98104 • 206-464-7090