Testing Spatial Transferability of Activity-Based Travel Forecasting Models

This paper reports results from the second phase of a two-phase FHWA-sponsored project to test and demonstrate empirically the transferability of activity-based model (ABM) systems between regions. With data obtained from the 2008–2009 National Household Travel Survey, researchers estimated ABMs simultaneously for 13 metropolitan regions in seven U.S. states. Statistical tests were used to test transferability, including tests of regional differences in the model coefficients, likelihood ratio tests of model equivalence, and transferability indexes, which measure the degree of model differences. In addition, differences in prediction sensitivity between locally estimated and transferred models were tested. The project overall found evidence in favor of transferability. It also found that parameters associated with land use, logsum accessibilities, and travel time and cost caused the biggest problems with transferability. Finally, the study found that transferring within a state or between regions with similar urban density improves transferability. This paper presents the data, models, and testing methods used in the project and includes details of all tests and results related to the improved transferability associated with model transfers from regions within the same state or with similar urban density. The conclusion of the study was that agencies considering transfer of an ABM from another region would do well to find a region within the same state or with similar urban density that has a model that is well supported by a large household travel survey data set.