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Activity Based Modeling: A Brief Introduction. Mike Neidhart, PhD, AICP Volusia County MPO. Florida Model Task Force Meeting November 29, 2007. MTF – 2 Track Focus. MTF work can be divided into 2 frames of thought (or tracks/focus)
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Activity Based Modeling: A Brief Introduction Mike Neidhart, PhD, AICP Volusia County MPO Florida Model Task Force Meeting November 29, 2007
MTF – 2 Track Focus • MTF work can be divided into 2 frames of thought (or tracks/focus) • Research based on how we can incrementally improve our existing model framework • Research model frameworks/philosophies that are 5-10 years into the future such as incorporation of meso and/or micro models, Activity Based models, etc. • This presentation will be on Activity Based Models
AMB Background • Activity Based Models (ABM) predict travel behavior as a derivative of activities (i.e., derived demand) • Travel decisions are part of a broader process based on modeling the demand for activities rather than merely modeling trips
AMB Background Continued • ABM belongs to the 3rd generation of travel demand models • Trip based 4-step models • Disaggregate trip based models • Activity based models • In ABM the basic unit of analysis is the activities of individuals/households
AMB Background Continued • ABM are based on the theories of Hägerstrand (1970) and Chapin (1974) • Hägerstrand focused on personal and social constraints • Chapin focused on opportunities and choices • Theory is that activity demand is motivated by basic human desires for: survival, ego gratification, and social encounters
Activity Demand • Unfortunately, it is difficult to model activity demand • However, research indicates that household membership moderates activity demand such that: • Households influence activity decisions • Effects differ by household type, size, membership relationship, age, and gender • Children impose significant demands and constraints on others in the household
ABM Approach (slide content: E. Zwerts) • Travel demand is derived from activities that individuals need/wish to perform • Sequence/patterns of behavior, not individual trips, are the unit of analysis • Household and other social structures influence travel and activity behavior • Spatial, temporal, transportation, and interpersonal interdependencies constrain activity/travel behavior
ABM Approach (slide content: E. Zwerts) • Activity based approaches reflect the scheduling of activities in time and space • Activity based approaches aim at predicting which activities are conducted where, when, for how long, with whom, by mode, and ideally also the implied route decision
ABM Paradigms (slide content: G. Jovicic) • ABM rely on the following 5 paradigms: • Travel is a derived demand from activity participation • Focus is on the sequence of activities/events • Activities are both planned within the context of the household • Activities are spread over a 24-hour period in a continuous manner rather than using “peak” and “off-peak” periods • Travel choices are limited in time, space, and by personal constraints
Hypothetical Travel Day Graphic by Goran Jovicic
How To Model Trips (slide content: G. Jovicic) • Trip-based model would model all 7 trips independent of the other trips • Tour-based model would model Tour 1 and Tour 2 independent of each other, while the Work Tour would be modeled as two independent trips • ABM would model the 4 activities and associated trips (work, meeting, shopping, and movie) as part of the same decision process
Criticism of Trip Based Models • Poor forecasting accuracy of trip based models most likely due to the model’s theoretical mis-specification • Trip based 4-step and disaggregate models have a fundamental error – they analyze each trip independently of other trips made by the individual • Trip based models fail to recognize the linkages among trips, between trips, and the activity participation by the individual
Advantages of ABM • Theoretically based on human behavior • Better understanding and prediction of traveler behavior • Based on decision-making choices present in the “real-world” • Use of disaggregate data • Inclusion of time-of-day travel choices
References • Jovicic, G.: Activity Based Travel Demand Modelling: A Literature Study. Danmarks TransportForskning Publishing, Note 8, 2001. • Bowman, J. L. & Ben-Akiva, M.: Activity Based Travel Forecasting. tutorial on activity based travel forecasting taught at conference of same name in New Orleans, Louisiana, June 2, 1996. • Shiftan, Y.; Ben-Akiva, M.; Proussaloglou, K.; deJong, G.; Popuri, Y.; Kasturirangan, K. & Bekhor, S.: Activity Based Modeling as a Tool for Better Understanding Travel Behaviour. Paper presented at the 10th International Conference on Travel Behaviour Research, Lucerne, August 2003. • Zwerts, E. (in cooperation with E. Moons & D. Janssens): Activity-Based Modelling: An Overview. PowerPoint presentation, Limburgs Universitair Centrum, Universitaire Campus, gebouw D, 3590 Diepenbeek, Belgium.