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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.
