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John L. Bowman, Ph. D. Bowman Research and Consulting 28 Beals Street Telephone: 617-232-8189 |
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Project Documents
SACSIM Activity-Based Travel Forecasting Model for SACOG, Featuring DAYSIM—the Person Day Activity and Travel Simulator
Last updated on May 20, 2008
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Ben-Akiva, Moshe., John L. Bowman and Dinesh Gopinath. (1996) Travel demand model system for the information era, Transportation(23), pp. 241-266.
Proposes a comprehensive travel demand modeling framework to identify and model the urban development decisions of firms and developers and the mobility, activity and travel decisions of individuals and households.
Abstract (PDF) Pre-publication draft of paper (not currently available)
Bowman, John. L. (1995) Activity based travel demand model system with daily activity schedules, Master of Science Thesis in Transportation, Massachusetts Institute of Technology, 92 pages.
Presents an integrated activity based discrete choice model system of an individual's daily activity and travel schedule, intended for use in forecasting urban passenger travel demand. The system is demonstrated using data from the Boston metropolitan area.
Abstract (PDF) Thesis (220K PDF)
Bowman, John L., and Moshe E. Ben-Akiva (1997) Activity
based travel forecasting, in Activity-Based Travel Forecasting
Conference, June 2-5, 1996: Summary, Recommendations and Compendium of
Papers, New Orleans, Louisiana. USDOT report #DOT-T-97-17, 32 pages.
An examination of the theory underlying activity based travel forecasting models, and the classification of the differences among modeling approaches, provide a framework that is used to compare six important examples.
Abstract (PDF) Paper (118K PDF) View paper online at TMIP Website
Ben-Akiva, Moshe E., and John L. Bowman (1998) Activity based travel demand model systems, in Equilibrium and Advanced Transportation Modeling, P Marcotte and S Nguyen, ed., Kluwer Academic Publishers, 20 pages.
Traces the evolution of disaggregate discrete choice travel demand models toward an activity basis.
Bowman, J. L. and M. E. Ben-Akiva (2001) Activity-based disaggregate travel demand model system with activity schedules, Transportation Research Part A, 35(2001), pages 1-28.
A refined and shortened version of Bowman's Master's thesis (see above).
Abstract (PDF) Pre-publication draft of paper (119K PDF)
Ben-Akiva, Moshe E. and John L. Bowman (1998) Integration of an activity-based model system and a residential location model, Urban Studies, 35(7), pp. 1231-1253.
Presents an integrated discrete choice model system of a household’s residential location choice and its members’ activity and travel schedules.
Abstract ( PDF) Pre-publication draft of paper (562K PDF)
Bowman, John L. (1998) The day activity schedule approach to travel demand analysis, Ph.D. Dissertation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. 185 pages.
Further develops the activity schedule model, emphasizing (a) the influence of activity accessibility on activity participation, at-home vs on-tour decisions, trip chaining and inter-tour trade-offs, and (b) the influence of lifestyle on activity and activity pattern utility. Includes an empirical implementation of the model system for Portland, Oregon.
Synopsis (PDF) Thesis (658K PDF) View thesis online in the MIT digital library of theses
Bowman, John L., Mark A. Bradley, Yoram Shiftan, T. Keith Lawton and Moshe E. Ben-Akiva (1998) Demonstration of an activity based model system for Portland, 8th World Conference on Transport Research, July 12-17, 1998, Antwerp, Belgium.
Reports the first operational implementation, in Portland, Oregon, of the activity-based travel demand model system proposed in 1994 by Ben-Akiva, Bowman and Gopinath.
Abstract (PDF) Pre-publication draft of paper (80K PDF)
Bowman, John L., and Moshe E. Ben-Akiva (1999) Incorporating Activity Utility, At-home Activities and Lifestyle in an Activity-based Travel Demand Model, working paper.
A shortened version of Bowman's Ph.D. dissertation (see above).
Abstract (not separately available) Paper (100K PDF)
Bradley, Mark A. , John L. Bowman and T. Keith Lawton (1999) A Comparison of Sample Enumeration and Stochastic Microsimulation for Application of Tour-Based and Activity-Based Travel Demand Models, European Transport Conference, September 1999, Cambridge, UK.
Abstract (not separately available) Paper (57K PDF)
Bowman, John L., Dinesh Gopinath and Moshe Ben-Akiva (2002) Estimating the probability distribution of a travel demand forecast, working paper.
Presents a practical method for estimating the probability distribution of a travel demand forecast. Given a forecast of any variable of interest, such as revenue or ridership, the approach identifies independent sources of uncertainty, estimates a probability distribution of each source, estimates the sensitivity of the variable to each source, and then combines the effects. A case study is presented in which the probability distribution of a revenue forecast is developed for a new transit system.
Abstract (not separately available) Paper (161K PDF)
Dong, Xiaojing, Moshe E. Ben-Akiva, John L. Bowman and Joan Walker (2003) Moving from Trip-Based to Activity-Based Measures of Accessibility, Transportation Research Part A, 40(2006), pages 163-180.
Studies the properties and performance of an
accessibility measure derived from the Day Activity Schedule (DAS) model
system, comparing it with traditional trip-based measures, including
isochrones, gravity-based measures and simpler utility-based measures.
Abstract (not separately available) Pre-publication draft of paper (143K PDF)
Bowman, John L. (2003) Logit kernel (or mixed logit) models for large multidimensional choice problems: identification and estimation, working paper.
Presents an identification rule and insights for estimation of the class of error component logit kernel models. These are logit kernel (or mixed logit) models involving heteroscedasticity and subsets of alternatives with shared unobserved attributes. A case study demonstrates the specification, identification and estimation of the type of model for which EC is useful—one with large choice set and a choice outcome consisting of two or more variables considered simultaneously.
Abstract (not separately available) Paper (884K PDF)
Vovsha, Peter, Mark A. Bradley and John L. Bowman (2004) Activity-based travel forecasting models in the United States: Progress since 1995 and Prospects for the Future , presentation at the EIRASS Conference on Progress in Activity-Based Analysis, May 28-31, 2004, Vaeshartelt Castle, Maastricht, The Netherlands.
Describes activity-based travel forecasting model systems implemented or under development in Portland, San Francisco, New York, Columbus and Atlanta, explaining attempts to incorporate behavioral realism, discussing issues that interfere with their acceptance in practice, and suggesting a research agenda relevant to implementation of practical activity-based models.
Abstract (not separately available) Paper (100K PDF)
Bowman, John L. (2004) A comparison of population synthesizers used in microsimulation models of activity and travel demand, working paper.
Microsimulation models that forecast the activities and travel of urban populations create synthetic populations and then use them to simulate the behavior of the households and persons in that synthetic population. The features of eight population synthesizers are compared, and suggestions are made for incorporating the best features into future population synthesizers.
Abstract (not separately available) Paper (200K PDF)
Bowman, John L. and Mark A. Bradley (2005) Disaggregate treatment of purpose, time of day and location in an activity-based regional travel forecasting model, European Transport Conference, October 2005, Strasbourg, France.
Presents model system design, data, and partial estimation results of the activity based regional travel forecasting model system for the Sacramento (California) Area Council of Governments (SACOG), as it stood while under development in September, 2005. Emphasis is placed on the techniques employed for effectively disaggregating the treatment of purpose, time and space.
Abstract (not separately available) Paper (90K PDF)
Bradley, M.A. and J.L. Bowman, A Summary of Design Features of Activity-Based Microsimulation Models for U.S. MPOs, white paper presented at the TRB Conference on Innovations in Travel Demand Modeling, May 21-23, 2006, Austin, Texas, 2006.
This short paper provides a concise summary of important design features of various activity-based model systems that had been implemented or recently designed as of May, 2006, for planning agencies in the U.S. The models described are those for Portland, San Francisco, New York, Columbus, Atlanta, Sacramento, Bay Area, and Denver.
Abstract (not separately available) Paper (43K PDF)
Bowman, J.L. and G. Rousseau , Validation of the Atlanta (ARC) Population Synthesizer (PopSyn), white paper presented at the TRB Conference on Innovations in Travel Modeling, May 21-23, 2006, Austin, Texas, 2006.
Presents the results of initial base year and backcast validation of the ARC Population Synthesizer (PopSyn).
Abstract (not separately available) Paper (58K PDF)
Bowman, J.L. and M.A. Bradley, Upward Integration of Hierarchical Activity-based Models, working paper, 2006.
Discusses the importance and difficulty of achieving upward vertical integration in activity based models, and a few techniques used by Bowman and Bradley to achieve it.
Abstract (not separately available) Paper (25K PDF)
Bowman, J.L., M.A. Bradley and J. Gibb, The Sacramento Activity-Based Travel Demand Model: Estimation And Validation Results, presented at the European Transport Conference, September 18-20, 2006, Strasbourg, France, 2006.
A sequel to the 2005 ETC SACOG paper, this paper focuses on several aspects of the model system, including the time-of-day models, equilibration of demand and assignment, base year calibration, and sensitivity tests.
Abstract (not separately available) Paper (233K PDF)
Bradley, M.A., J.L. Bowman and B. Griesenbeck, Development and application of the SACSIM activity-based model system, submitted for presentation at the 11th World Conference on Transport Research, Berkeley, California, USA, June, 2007.
A condensed version of the 2005 and 2006 ETC papers, with an additional section on application issues.
Abstract (not separately available) Paper (78K PDF)
SACSIM is a regional travel forecasting model system, developed in 2005 and implemented in 2006 for the Sacramento (California) Area Council of Governments (SACOG). The system features an integrated econometric microsimulation of personal activities and travel (DAYSIM) with a highly disaggregate treatment of the purpose, time of day and location dimensions of the modeled outcomes. Here are various technical documents produced during the development and implementation of SacSim and DaySim. They provide a very detailed description of the model system. However, they are historical documents and may differ in some cases from the model’s initial or current implementation.
Package of all the
following documents (2409K Zip file)
Design and planning documents (pdf files)
Preliminary
design report (2002)
Addendum
(2003)
Technical
memo 1—Model System Design (early 2005) The best design overview of DaySim
Phase
2 Working Paper 2.1 (June 2005)
Models (pdf files)
Technical
memo 2—Population Synthesizer
Technical
memo 4—Mode Choice
Technical
memo 5—Intermediate Stop Location
Technical
memo 6—Day Pattern Activity Generation
Technical
memo 7—Time of Day/Activity Scheduling
Technical
memo 8—Usual and Tour Destination
Technical
memo 9—Household Auto Availability
Technical
memo 11—Impedance and Accessibility Effects
DaySim program (pdf files)
Technical
memo 3—Design of Model System Application Software
Technical
memo 10—DaySim05 Documentation
SacSim (pdf file)
Application
of an Activity-Based Travel Model of the Sacramento Region (SacSim)
September 21, 2006 draft
Papers (pdf
files)
Bowman, John L. and Mark A. Bradley (2005) Disaggregate treatment of purpose, time of day and location in an activity-based regional travel forecasting model, European Transport Conference, October 2005, Strasbourg, France.
Bowman, John L., Mark A. Bradley and John Gibb (2006) The Sacramento activity-based travel demand model: estimation and validation results, European Transport Conference, September 2006, Strasbourg, France.
Bradley, Mark A., John L. Bowman and Bruce Griesenbeck (2006) Development and application of the SACSIM activity-based model system, submitted for presentation at the 11th World Conference on Transport Research, June, 2007, Berkeley, California, USA.
The discrete response models in the above papers were all estimated with ALOGIT software. ALOGIT can be used to estimate very large MNL and nested logit models required in practical transportation and other choice model applications. The latest version, ALOGIT 4, can use simulation methods to estimate logit models with random parameters (ie, mixed logit, error-components logit, logit kernel). For information about ALOGIT see http://www.hcg.nl. For information about potential discounts, email John_L_Bowman@alum.mit.edu.