Definitions of the term by development economists have been less than precise (Ingram and Fay, 2008:301). Hirschman, for example, employing the umbrella term “social overhead capital”, defined infrastructure as those “basic services without which primary, secondary and tertiary productive activities cannot function” (1958: 83), and provided or heavily regulated by public agencies. He further distinguished a “hard core” of transportation and power (characterized by technical indivisibilities and a high capital-output ratio), from a softer group of more traditional public goods such as health and education.