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UrbanSim at Houston-Galveston Area Council

Modeling at H-GAC. Socioeconomic ModelingForecasting GroupUrbanSimTransportation ModelingTDM GroupEMME/2 ? Cube Voyager (summer 2006)UrbanSim2000-2003 Richard DeBose1st Forecast adopted May 20032nd Forecast : 11/12 2005. Principal Features of UrbanSim. AllocationCounty-level control totals (target levels)Spatial DisaggregationUser-defined regular gridAgent-basedHouseholdsWorkers (employers)Real estate developers.

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UrbanSim at Houston-Galveston Area Council

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    1. UrbanSim at Houston-Galveston Area Council

    2. Modeling at H-GAC Socioeconomic Modeling Forecasting Group UrbanSim Transportation Modeling TDM Group EMME/2 ? Cube Voyager (summer 2006) UrbanSim 2000-2003 Richard DeBose 1st Forecast adopted May 2003 2nd Forecast : 11/12 2005

    3. Principal Features of UrbanSim Allocation County-level control totals (target levels) Spatial Disaggregation User-defined regular grid Agent-based Households Workers (employers) Real estate developers

    4. Base Year Spatial System (Regular Grid) H-GAC: 1,000x1,000 ft; 250,000 grid cells Grid Attributes Housing units Value of residential improvements Com-ind-gov sq. footage Value of com-ind-gov improvement Proximity (highways, arterials) Physical features (% water, % open space, etc.) Other (GRID_ID, land use (development) type) “Cost” of Travel data Inter-TAZ logsums

    5. Base Year (cont.) Households Table with individual households (household_id) Attributes: GRID_ID, size (# of people), race, age (of hsh head), income, # of cars, # of workers Jobs Table with individual jobs (job_id) Attributes: GRID_ID, user-defined sectors H-GAC: Durables, Non-Durables, Mining, CTPU, FIRE-Services, Retail-Wholesale, Gov-Med-Ed

    6. Data Sources County Appraisal (housing units, non-residential sq footage, value of improvements) Info-USA (company-level data on location, sector, # of employees) Census (household attributes) Household “synthesis”: use marginal probabilities from PUMS to disaggregate SF-3 data Transportation (logsums, networks) Other (Landsat imagery, aerial photo, proprietary real estate databases)

    7. Control Totals UrbanSim only allocates future growth Regional (all grid cells combined) levels are determined exogenously Annual control totals for Households (optional segmentation) Jobs (optionally,by sector) A task in itself Buy or develop your own H-GAC: REMI in 2003, in-house model in 2005

    8. UrbanSim Sub-Models (Modules) Accessibility Household transition Employment transition Household location choice Employment location choice Land price Developer

    9. Annual Sequence of Events Accessibilities are “announced” (computed) Households are created/removed Jobs are created/removed New households select from the stock of available housing units New jobs “select” from the stock of available job spaces (1 job space = X sq ft) Market “announces” new land values (computed) Developers build new housing units and non-residential sq. footage

    10. Accessibility Module Uses logsums to compute accessibility to housing, employment, different land uses, recent developments Conveys information about the Spatial distribution of housing and jobs Disutility (cost) of travel Transportation network Is computed for every grid cell, for every activity Exponential distance (cost) decay function

    11. Household Transition Module Simulates aggregate results of family dynamics People are born, marry, divorce, die No aging! “Updates” (removes/creates) current households to match the Target (Control Total) Creates vacant units (when a household is removed) Puts “unplaced” (newly created) households (GRID_ID=0) in a buffer

    12. Employment Transition Module Simulates aggregate results of employment dynamics New jobs created, old jobs terminated “Updates” (removes/creates) current jobs to matches the Target (Control Total) Creates vacant slots (when a job is removed) Puts “unplaced” (newly created) jobs (GRID_ID=0) in a buffer

    13. Relocation Modules Household Relocation Module Employment Relocation Module User-specified % of households, jobs wishing to change location Puts households, jobs in a buffer and releases houses units, job slots H-GAC: not used

    14. Household Location Choice Module Simulates household decisions on where to reside Applies to “unplaced” households Selection from a stock of available housing Procedure: Group unplaced households by attributes Sample available locations Assign probabilities (from multinomial logit model) Cost/income ratio, access to employment, housing within walking distance Use Monte Carlo sampling to pick location and assign GRID_ID

    15. Employment Location Choice Module

    16. Land Price Module Simulates the determination of land values by the market Parameters from Hedonic regression Site and location attributes

    17. Developer Module Simulates actions of the real estate developers Creates new residential units and non-residential sq. footage Most important module Households/employment locate only in available housing/space. Development Types (for grid cells) min, max (units, sq footage) 8 residential, 8 mixed, 3 commercial, 3 industrial, 1 gov, 1 vacant, 1 undevelopable

    19. Developer Module (cont.) “Transitions” define Real Estate Development Transitions Within the same dev type From one type to another Only certain transitions are allowed (user-defined)

    20. Developer Module (cont.) Transition Probability Estimation Multinomial logit Choice set includes no-build alternatives P is a function of grid cell’s and local attributes Recent transitions, land value, % open space Sampling setup Artificial observation with 5 alternatives (1 transition) Different grid cells Calibration (frequency of transitions)

    21. Developer Module (cont.) Simulation Apply Constrains (exclude certain grid cells) Determine Build or NO build If Build, then determine quantities Distribution for new construction (min, max, mean, std) Vacancy Adjustment Speed up development if vacancy is low, slow down if vacancy is high

    22. Events Deterministic component Under construction or planned (known or likely to occur) Grid-specific Development Events Employment Events Land use Events

    23. Running UrbanSim UrbanSim “Scenario” (instructions) file Specify the forecast horizon Specify years to output Reports future grid cell conditions Aggregate from grid cells to TAZ Households (by attributes) Jobs (by sector) Give results to transportation modeling group

    24. Running UrbanSim (cont.) Base year - 2005 Run 2005-2007 simulation Save 2007 conditions (grid cells, jobs, households) Make 2007 a base year Update Logsums, Proximities, Travel time Base year - 2007 Run 2007-2010 simulation Continue …

    25. Running UrbanSim (cont.) Future travel networks and accessibilities Phase 1: 2005-2007 (2005 travel data) Phase 2: 2007-2010 (2007 travel data) Phase 3: 2010-2013 (2010 travel data) Phase 4: 2013-2015 (2013 travel data) Phase 5: 2015-2025 (2015 travel data) Phase 6: 2025-2050 (2025 travel data) 8 separate models (each county)

    26. UrbanSim Work Flow Process Define basic framework (grid, development types) and assemble data (base year and control totals) Run the “consistency checker” utility Run the “estimation data writer” utility Prepares data for statistical modeling Develop specification and estimate parameters (SAS) Art/science, no general solution Validate parameters Recreate past conditions (e.g., 1990), simulate development, compare with actual (e.g., 2000) Populate the UrbanSim tables (model specification and coefficients) Run the simulation Tabulate and map results

    27. Technical Details Constantly evolving software Stable and nightly releases Open source Written in Java, will be re-written in Python Out next year (?): OPUS MySQL server, MySQL table format About 60 tables (some are optional) per region worth 500 MB (can be smaller) Batch files (calls to DOS, MySQL, UrbanSim)

    28. H-GAC Plans for 2005-07 Parcel-level regional database Fill the gaps for exempt parcels Merge 8 counties into a single model Revise development types Address “sq ft per job” and “sector-sq ft type” problems Include home-based employment Automate grid cells table creation Data? Code? UrbanSim Re-do statistical modeling Thorough validation

    29. Wish List Link Jobs and Households create WORKERS table with job_id and household_id Differentiation between renting and owning Differentiation between single- and multi-family housing units Separate Redevelopment Module Detailed non-residential space categorization (office building, large retail, school, etc) Group quarters

    31. Lessons Learned Incredible Fun If you like GIS + stats + DBMS + complex systems Major commitment Invest in a parcel-level database Don’t make it grid-centric Design the information system and data collection procedures with updates in mind Front-end QA/QC Documentation! Automation Recurring tasks

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