Point-Base Household and Job Geographic Datasets Jill Locantore, Land Use Planner Jeremy Papuga, Demographic Analyst Erik Sabina, Regional Modeling Manager DeVon Culbertson, IT Services Manager TRB Transportation Planning Applications Conference, Daytona Beach, Florida, May 6-9, 2007.

DRCOG’s Integrated Regional Model New land use and travel model Disaggregate, activity-based –San Francisco family of models Scheduled release Summer 2008 –Model estimation and software in process Part of broader organizational move towards disaggregate data –DRCOG’s Regional Data Model

Regional initiatives demand better analysis – particularly of alternative travel modes Transit Oriented Development (TOD) Urban Centers

Challenges of modeling walk and transit trips: TAZs

Problems associated with TAZs Throws away data –Point-level info from travel survey Aggregate bias –Tends to overestimate walk trip distances Model insensitivity –Ignores land use patterns within TAZ

Cascading effects Overestimate walk distance Underestimate walk and transit trips Overestimate automobile trips Overestimate mobile emissions Underestimate benefits of TOD, Urban Centers

Rejected alternative 1: Subdivide TAZs

Rejected alternative 2: Distributed distance

More Problems, and a Solution? Problems: –Added complexity, limited improvement –Consistency between walk access transit and walk trips Possible solution: –Operate at the point level Issues: –Do we have the data? –Can we do it?

Do we have the data? Employment =Yes –Source: Quarterly Census of Employment and Wages (QCEW) –Data from Colorado Department of Labor –Geocoded based on address and zip code –84,950 point locations, representing 1.4 million jobs

Do we have the data? Households = Sort of –Residential utility hook-ups Issues to address –Model estimation is based on 2000 data, but oldest utility points are from 2002 –No indication of occupied vs. unoccupied units

Creating household points The data we used –Utility hook-up data –DRCOG annual population & household estimates –2000 Census data, Summary file 1 –GIS Layers: Census tracts and blocks

Issue 1: Going from 2002 to 2000 Compare DRCOG’s 2002 tract-level housing unit estimate with 2000 census data If positive unit growth 2000 – 2002 –Randomly remove points –Control to 2000 census block-level housing units If negative unit growth 2000 – 2002 –Randomly duplicate points –Control to 2000 census tract-level housing units

Issue 2: Accounting for vacancies Need to accurately model households, not housing units –Randomly remove additional points based on 2000 vacancy rates –Control to 2000 census tract-level households

Example: Removing Points

Blocks with no housing units in 2000

Example: Removing Points Blocks with no housing units in 2000

Example: Removing Points Random removal of additional points

Where We Go From There Created skims for model estimation –Rectangular and hypotenuse distances Evaluating methods for developing future year point data –Traditional assumption – all households and jobs are located at TAZ centroid – sets the bar low –One step at a time. Better, not perfect.

Where We Go From There Disaggregate modeling = opportunities for improvement –Detailed modeling of land use within TAZs –Better analysis of TOD and Urban Centers Will be using model for 2040 planning analysis.

Questions? Jill Locantore Erik Sabina DeVon Culbertson