A methodology for generating disaggregate truck data for Texas' statewide analysis model

The following research describes a novel approach for generating disaggregate county-level truck data for Texas from publicly available freight data sources. County-level truck flows are required as inputs to the Statewide Analysis Model (SAM), a multi-modal freight planning model developed by the Texas Department of Transportation, to analyze the freight system performance and make critical infrastructure improvement decisions. TxDOT currently relies on the commercial Reebie Associates’ TRANSEARCH database for inputs to the SAM, since it is the only available freight data source providing comprehensive county-level truck flow data for Texas. However, the sources, methodology, and assumptions used in compiling the database are proprietary, which have raised questions regarding the reliability of the data. Since statewide primary freight data collection is an expensive and time-consuming process, there is a need for methods to extract disaggregated data from secondary freight data sources. The current research addresses this need by developing a model to generate county-level truck flows for Texas from the publicly available Commodity Flow Survey. The methodology is applied to compute inter-county, county-to-state and state-to-county truck flows for Texas for nine major commodity categories. Though the generated truck data suffer from certain limitations associated with the CFS, the approach provides a cost-effective means of estimating county-level truck flows in Texas, of which the limitations, assumptions and measures of reliability are well documented