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Activity Based Models Review

Activity Based Models Review. presented to Model Task Force Model Advancement Committee presented by Thomas Rossi Krishnan Viswanathan Cambridge Systematics Inc. Date November 24, 2008. Presentation Overview. Study Background and Objectives Models Studied Study Findings Discussion.

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Activity Based Models Review

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  1. Activity Based Models Review presented toModel Task Force Model Advancement Committee presented byThomas Rossi Krishnan Viswanathan Cambridge Systematics Inc. Date November 24, 2008

  2. Presentation Overview • Study Background and Objectives • Models Studied • Study Findings • Discussion

  3. Study Background and Objectives • Examine existing activity based models to determine model features, application procedures, and requirements • Determine planning analysis needs for which travel models are used • Summarize the ability of activity based models to provide accurate information for planning analysis needs

  4. Models Studied • Urban Models • San Francisco County, CA (2001) • New York, NY (2002) • Columbus, OH (2005) • Sacramento, CA (2007) • Lake Tahoe, NV/CA (2007) • Atlanta, GA • Portland, OR • Denver, CO • San Francisco Urban Area (MTC), CA

  5. Models Studied (Cont’d) • Statewide Models • Ohio Model (2007) • Oregon Model • Research Models • FAMOS (University of South Florida) • CEMDAP (University of Texas) • TASHA (University of Toronto)

  6. Models Studied (Cont’d)

  7. Study FindingsModel Structure • All models estimated from household activity/travel survey • Same type of survey used for four-step model development • Individuals in region’s population are simulated • Activity patterns • Locations and times of activities • Modes used to travel between activity locations

  8. Study FindingsModel Structure (Cont’d) • Model structure • Generate daily activity patterns • Location, time and mode made at two levels : Tour and Trip • Five to eight activity purposes • Work, school, shop, meal, social/recreation, and personal business • Some models consider household interactions • Implications for time of day and mode choice • Is it cost effective to include this to gain accuracy? The “jury is still out.”

  9. Study FindingsModel Components • Population Synthesizer • Long Term Choice Models • Auto ownership • Usual workplace location • Daily Activity Pattern Models • Tour Level Models (primary activity) • Destination choice • Mode choice • Time of day choice

  10. Study FindingsModel Components (Cont’d) • Trip Level Models (intermediate stops) • Destination choice • Mode choice • Time of day choice • Trip Assignment • Highway • Transit

  11. Study Findings Model Development Process • Model development between 1.5 to 8 years (typically 2-3 years) • Model development costs – typically $600,000-$800,000 • Consultants nearly always used for model development • Most models used local household activity survey data along with other sources such as transit on-board, external or visitor surveys • Lake Tahoe model was transferred from Columbus

  12. Study FindingsModel Execution • Standard transportation modeling software such as CUBE/Voyager, TransCAD used along with custom programs in C++, Java, or Python • Run times range from 10 hours to 2 days • Distributed computing preferable to reduce runtime • Models need around 7 to 10 GB of storage per run • Most models run only in-house

  13. Study FindingsPolicy Planning Analysis • Activity Based Models benefit the following types of analysis • Congestion Management Systems  • Toll Feasibility Studies  • High-Occupancy Vehicle (HOV) Lane Studies  • New Starts/Small Starts Analyses • Hurricane Evacuation Modeling Support  • Air Quality Conformity Determinations  • Integrated Land Use Model  • Incorporate Ability to Test Impact of Gasoline Prices  • Freight Studies • Growth Management/Concurrency Applications

  14. Study FindingsData Needs • No special data needs required to develop activity based models beyond what is used for four-step models • Existing household travel surveys can be used to develop data for activity based models • Other data sources such as transit on-board surveys, external and visitor surveys are also helpful for activity based models • Census data sources such as PUMS useful for population synthesis • ACS disclosure rules can be problematic

  15. Conclusions • Models use similar approaches • Main differences related to explicit modeling of household interactions • Members of population simulated individually • Their activities, locations, times, and mode choices • Standard modeling software used along with custom programs • Typically 2-3 years, $600,000-$800,000 to develop models • Run times typically 0.5 to 2 days

  16. Discussion

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