The research conducted under this project updated and refined the dataset constructed as part of the initial efforts in NCHRP Project 2-17(3) and formulated a procedure for future maintenance and updates of the dataset. The updated dataset is available on the Bureau of Transportation Statistics' website. The research findings are summarized in NCHRP Research Results Digest 248, "Updated and Enhanced Database for Macroeconomic Analysis of Transportation Investments and Economic Performance."

Quantitative linkages need to be determined between transportation investments and economic activity as measured in terms of employment, expenditures, income, production of goods and services, productivity, and competitiveness. While economists differ in their opinions concerning the true significance of each factor contributing to productivity, they do agree that productivity and national income are influenced by the amount of capital that labor has to work with and that the amount of capital at any given time is a result of past levels of savings, investment, and depreciation. The initial phase of NCHRP Project 2-17(3) identified opportunities for improvements to the models developed in previous work and established the data requirements for formulating a wider range of fundamental relationships between factors. The phase resulted in the development of an enhanced set of data related to transportation investments, economic performance, and demography. The data provided the basis for limited investigations into the validity of recently developed models of transportation investments and the derivation of new models. These analyses verified the usefulness of the dataset resulting from this research and provided the impetus and direction for enhancement and update of the dataset to allow continued research in this area.