Land use forecasting at the PSRC has undergone significant change over the last year, culminating with the deployment of a new land use forecasting system in the region. This project began in 2003 with collaboration between PSRC and the University of Washington’s Center for Urban Simulation and Policy Analysis (CUSPA), headed by Dr. Paul Waddell. Previous land use forecasting at PSRC was completed using a zone-based land use forecast model (DRAM/EMPAL), while current and future land use forecasting will be completed using the UrbanSim parcel-based model. UrbanSim was designed to reflect dynamic urban systems by focusing on the real estate market, the transportation system, and the cumulative effects of interventions on patterns of development, travel demand, and household and firm location. This change will better inform public policy deliberation by simulating long-term, significant effects on growth patterns.

Key Design Features of UrbanSim

• Simulates the location decisions for each household and job in the region (known as micro-simulation)
• Produces a forecast for each year in the simulation (currently out to 2040)
• Tailored to interact with PSRC’s travel models so the impacts of land use on transportation, and vice-versa, can be modeled
• Predicts land development at a parcel level
• Requires as an input an interpretation of how many housing units or square feet of building space can be built under existing comprehensive plans, including adjustments for environmentally-sensitive areas.

Status (As of Summer 2011)

PSRC staff first installed UrbanSim in-house in January 2008, leading to a year-long testing and adjustment phase. In March 2009, UrbanSim was utilized for the first time to support the analysis work for the update of the region’s long-range transportation plan, Transportation 2040. The phasing-in of UrbanSim has continued through 2010 and 2011, including additional model refinements and review of forecast output. Pending successful testing, UrbanSim will be used to generate an updated small area forecast in early 2012.