TRB 2016 Blue Ribbon Committee
16th National Transportation Planning Applications Conference

Integrated Performance Impact Analysis – Linking Travel Modeling and Economic Modeling

Corresponding Author: Sheldon Harrison, Cambridge Systematics, Inc.

Presented By: Sheldon Harrison, Cambridge Systematics


In early 2016, the Georgia Department of Transportation (GDOT), in collaboration with the Governor’s Office, undertook a macroeconomic analysis of a package of large-scale, highway improvement projects throughout the state. Existing statewide and regional travel demand models were applied, along with an economic analysis tool developed specifically for Georgia. Given the fact that separate travel demand models with different assumptions (Time of Day versus Daily assignment, for example) were used, it was necessary to develop a standardized methodology for extracting and applying travel demand data needed as input for the economic analysis.

The presentation will describe the modeling assumptions used for the analysis. It will highlight the automated procedure used to format the outputs, the basic geographic unit of the analysis (REMI regions), and describe the travel demand model metrics used by the economic tool for comparison purposes. Examples of the reported metrics include the VMT, VHT, and vehicle delay grouped into specific stratifications such as truck, leisure, commute or business trips. Given that each model has different reported trip definitions that don’t neatly align with the desired economic analysis definitions, the assumptions used to stratify the trips will be described. A brief discussion will then be undertaken on the other non-model activity inputs used by the economic tool such as income, pavement costs, value of time etc., and finally a description of how the results were packaged to put it in a statewide planning context for decision makers will be provided.


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