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C O M P R E H E N S I V E E C O N O M E T R I C M I C R O S I M U L AT O R 81 TABLE 4 Impact of IVTT on PHT Home-Based Work Home-Based Other Non-Home-Based Overall PHT* % Diff. PHT* % Diff. PHT* % Diff. PHT* % Diff. Base case 1.68 -- 3.12 -- 0.79 -- 5.59 -- 10% increase 1.77 5.53 3.10 0.73 0.78 0.74 5.66 1.15 25% increase 1.91 13.89 3.06 1.89 0.78 1.34 5.76 2.93 10% decrease 1.58 5.73 3.15 0.94 0.80 0.84 5.53 1.08 25% decrease 1.44 14.13 3.21 2.64 0.81 2.67 5.46 2.39 *PHT is in millions of hours. SUMMARY CEMDAP and NCTCOG results, and (g) predictions for a future year and corresponding comparisons with The CEMDAP project represents a significant effort in NCTCOG model results. the development and implementation of an activity- based travel forecasting system. The recent efforts by the researchers have been focused on incorporating sev- ACKNOWLEDGMENTS eral enhancements (such as modeling the travel pat- terns of children and incorporating childrenparent The authors appreciate the help of the NCTCOG travel interactions) to the overall modeling framework and modeling team in the CEMDAP sensitivity testing applying the framework to an expanded 4,874 zone efforts, for providing the data for model estimation, and system in the DallasFort Worth area. All the models for their overall support of this research effort. The have been reestimated for this new zoning system with research is sponsored by the Texas Department of household travel survey and disaggregate land use and Transportation. interzonal level-of-service data from the DallasFort Worth area. The researchers are now engaged in the implementa- REFERENCES tion and integration testing of the software for the expanded and enhanced software version. Simultane- Bhat, C. R., J. Guo, S. Srinivasan, and A. Sivakumar. Activity- ously, data inputs are being assembled for evaluation Based Travel Demand Modeling for Metropolitan Areas in and sensitivity testing of the software outputs. Texas: Software-Related Processes and Mechanisms for the The tasks planned for the immediate future include Activity-Travel Pattern Generation Micro-Simulator. the following: (a) comparison of the travel patterns pre- Report 4080-5, Center for Transportation Research, Uni- dicted for the estimation sample against the observed versity of Texas at Austin, Oct. 2003. patterns in the activity-travel survey, (b) complete soft- Guo, J. Y., S. Srinivasan, N. Eluru, A. Pinjari, R. Copperman, ware run for the entire baseline population (synthetically and C.R. Bhat. Activity-Based Travel-Demand Analysis for generated for Year 2000), (c) evaluation of sampling Metropolitan Areas in Texas: CEMSELTS Model Estima- strategies, (d) comparisons of CEMDAP outputs with tions and Prediction Procedures, 4,874 Zone System CEM- those from four-step models currently employed by DAP Model Estimations and Procedures, and the SPG NCTCOG, (e) validations against ground counts and Software Details. Report 4080-7. Center for Transporta- other measures, (f) sensitivity tests and comparisons of tion Research, University of Texas at Austin, Oct. 2005.