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12 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 2 TABLE 1 Comparison of Design Features of Various Activity-Based Model Systems Model Design Portland San Francisco New York Columbus Feature METRO SFCTA NYMTC MORPC Controls and no. of categories for 4 household sizes, 4 household sizes, 5 household sizes, 5 household sizes, population synthesis 4 incomes, and 3 no. of workers, 4 no. of workers, 4 no. of workers, 4 ages 4 incomes, and and 4 incomes and 4 incomes 3 ages "Usual" work and school locations at top level? Noyes Yes No No Number of out-of-home activity purposes 3/8 3 4 7 Number of in-home activity purposes 3 1 1 1 Day pattern type linked explicitly across HH? No No No Yes, sequential Joint activities linked explicitly across HH? No No No Yes Allocated HH activities allocated explicitly? No No No Yes "Escort" trips linked explicitly across HH? No No No No Level where stop purpose and frequency modeled Person-day Person-day Tour Tour Network zones used (approx.) 1,250 1,900 6,000 2,000 Smaller spatial units used below zones? Noyes, 20K blocks No No No Mode and destination model estimation Simultaneous Sequential Sequential Sequential Network time periods per day 5 5 4 5 Modeled time periods 5 per day 5 per day 4 per day 1 hour Use of time window duration in scheduling? No No No Yes Tour time of day relative to mode Above both Above both Between them Between them and destination Departure time modeled separately at trip level? No No (may be added) No No Accessibility measures in upper level models Person-specific Jobs reached by Destination choice Destination choice modedestination zonemodetime logsums by zone logsums by zone logsums band modesegment modesegment a These model systems are currently in the design phase. HH = households. behaviorally and because Census Transportation "USUAL" WORK AND SCHOOL LOCATIONS Planning Package Table 1-75 provides a useful three- MODELED AT TOP LEVEL way joint distribution of household size, number of workers, and income for 2000. The Portland Metro The research community recognizes that the choices of and San Francisco County Transportation Authority where to work and go to school are longer-term decisions models have also used age of head of household as a that are not adjusted day to day, similar to the choice of control variable, and the Atlanta Regional Commis- residence (which is implicitly modeled in the synthetic sion, the Bay Area (California), and Denver are all sample). In most models, and all the more recent ones, considering using age or age-related variables as well the "usual" work and school places are modeled at the (e.g., presence of children, senior citizens, or both). top level, meaning that these are predicted before any The sample-generation software created for Atlanta choices specific to the travel day are predicted. The home has a flexible system for designating and combining location is typically one of the alternatives in the choice control variables, as well as facilities for testing how set for people whose main workplace is at home or who well the synthetic population matches other variables are homeschooled. Certain types of individuals, such as for which there has not been explicit control. An construction workers or traveling salespeople, may not important test will be how well the age distribution is have a usual workplace. And this model formulation matched when age is not one of the explicit control requires that data be collected on each worker's most fre- variables. quent work location, even if that person does not visit