THE DEVELOPMENTAL IMPACTS OF TRANSPORTATION INVESTMENTS

This paper deals with the developmental impacts of infrastructure investments in general and transportation investments in particular. The perspective is that of an analyst who must predict either (or both) the net economic benefits or the economic impacts of alternative public expenditure programs on transportation infrastructure. The paper necessarily must transcend theoretical and empirical issues in order to determine the most appropriate means of measuring benefits and impacts. The most salient theoretical issues involved in benefit measurement and impact projection are raised first. Next, issues related to the empirical estimation of economic impacts of infrastructure investments are reviewed, including major strengths and weaknesses of alternative approaches, obstacles to the accurate measurement of economic impacts, data sources and data limitations. Finally, specific methods are detailed to accomplish these two goals.