Transcript Slide 0

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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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
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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
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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)
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Models Studied (Cont’d)
Atlanta
Portland
Denver
San
Francisco
(MTC)
2007
2008
(est.)
2008
(est.)
2008
(est.)
2009
(est.)
2000
2000
2005
2000
2035
2030
2035
2030, 2050
2001
1994
1997
SFCTA
New
York
Columbus
Sacramento
Lake
Tahoe
Year Completed
2001
2002
2005
2007
Base Year
2000
1996
2000
2005
2020
2030
Forecast Year
Ohio
Oregon
2007
2008
(est.)
2000
2003
No
Survey
Survey Data Year
1990
1998
1999
2000
Number of
Households in Survey
1,300
11,000
5,600
3,900
1,220
8,100
6,000
4,900
15,000
15,000
No
Survey
1,700
(750 in
SF)
3,600
1,800
1,500
289
2,000
2,000
2,800
1,454
5,300
3,000
Zones (approximate)
Area Size
(square meters)
50
(SF only)
150
(est.)
4,000
501
Base Year Population
750,000
(SF only)
1,500,000
2,000,000
63,448
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4,700,000
500
7,000
1,600,000
6,783,760
Study Findings
Model 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
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Study Findings
Model 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.”
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Study Findings
Model 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
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Study Findings
Model Components (Cont’d)
Trip Level Models (intermediate stops)
• Destination choice
• Mode choice
• Time of day choice
Trip Assignment
• Highway
• Transit
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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
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Study Findings
Model 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
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Study Findings
Policy 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
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• Growth Management/Concurrency Applications
Study Findings
Data 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
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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
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Run times typically 0.5 to 2 days
Discussion
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