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A C T I V I T Y- B A S E D M O D E L S 29 modeling route choice behavior by means of detailed and transportation system characteristics simulator GPS data obtained through PARROTS. Adopting (CEMSELTS) provides the sociodemographics and activ- knowledge from existing route choice models and cali- ity environment. These characteristics link to the activity- brating it for use in an activity-based context are also travel simulator, CEMDAP, which generates individual anticipated. Calibrating current models on real-world travel patterns. These are loaded into a dynamic traffic data will also be performed, along with improving com- assignment to develop link volumes and speeds. The link putation time for large-scale simulations. The concepts volumes and speed are fed back into CEMSELTS. currently used in Aurora, such as estimating S-curves as CEMDAP uses base-year inputs that include aggre- utility functions, estimating the effect of context vari- gate zonal-level demographic characteristics, land use ables on maximum utility, evaluating the scheduling patterns, the transportation network and level of service component, and extending learning facets, will be tested (LOS) measures, and any potential policy actions and evaluated. Additional concepts will be added, planned for a future year. The outputs for the forecast including the impact of life trajectory events, the impact year include detailed activity-travel patterns. When the of regular events, and strategic decisions. dynamic microassignment component is added, it will provide link volumes and speeds by time of day for the forecast year. COMPREHENSIVE ECONOMETRIC The modeling framework characterizes the MICROSIMULATOR FOR DAILY ACTIVITY-TRAVEL activity-travel patterns of all household members, PATTERNS: RECENT DEVELOPMENTS AND including adults, children, workers, nonworkers, stu- SENSITIVITY TESTING RESULTS dents, and nonstudents. It explicitly considers spacetime interactions and constraints. It models the Chandra Bhat, Abdul Pinjari, Naveen Eluru, allocation of maintenance activities, such as shopping, to Ipek Sener, Rachel Copperman, Jessica Guo, and household members and models parents' escorting chil- Sivaramakrishnan Srinivasan dren to and from school. It generates and links joint activities of parents and children. CEMDAP adopts an Chandra Bhat discussed Comprehensive Econometric interleaved approach to the generation of activity-travel Microsimulator for Daily Activity-Travel Patterns patterns of all household members. It models 11 out-of- (CEMDAP), which is a continuous-time activity-travel home activity purposes for adults and three out-of-home prediction software currently being applied and evalu- activity purposes for children. ated in the DallasFort Worth Metropolitan area. Vol- The temporal resolution is a continuous time scale. ume 2 provides a paper on the topic.2 The following The LOS data can be provided at any temporal resolu- points were covered in his presentation. tion. Five time-of-day periods are being used in the Dal- lasFort Worth area application. The spatial resolution The development and testing of CEMDAP was allows for any number of zones. The DallasFort Worth funded by the Texas Department of Transportation application uses 4,874 zones. A standard Windows- (TxDOT). Janie Bynam and Bill Knowles of TxDOT and based graphic user interface is used with CEMDAP. This Ken Cervenka of North Central Texas Council of Gov- interface allows users to modify model parameters and ernments provide assistance on the project. CEMDAP is also provides a diagrammatic interface to help the user based on a system of econometric models, with each understand the logic of the system and the underlying model corresponding to the determination of one or models. more activity-travel attributes. The models are applied in The CEMDAP software architecture allows for a systematic sequence to generate the daily activity and rapid implementation of system variants and expansions. travel patterns of all members of each household in the Recent enhancements include the ability to model both study area. adults and children incorporating spatiotemporal inter- At a conceptual level, base-year inputs include dependencies, the incorporation of additional policy- aggregate sociodemographics, activity-travel environ- sensitive variables to LOS, and the ability to process ment characteristics, policy actions, and model parame- larger samples. ters. The synthetic population generator provides input The synthetic population generator provides flexi- to construct the detailed individual-level sociodemo- bility in how variables are aggregated. It supports differ- graphics for the base year. The socioeconomic, land use, ent variable combinations to be synthesized and provides synthetic population for census tracks, block groups, or 2 blocks. The synthetic population generator accounts for See Bhat, C., A. Pinjari, N. Eluru, I. Sener, R. Copperman, J. Guo, both household- and person-travel control totals. and S. Srinivasan. Comprehensive Econometric Microsimulator for Daily Activity-Travel Patterns: Recent Developments and Sensitivity CEMDAP was applied to examine a 10% and a Testing Results. Volume 2, pp. 7881. 25% increase in in-vehicle travel times and a 10% and a