Of the major kinds of physical infrastructure, electricity generating capacity has roughly the same marginal productivity as physical capital as a whole. So have roads-plus-rail, globally and in lower-income countries. Telephones, however, and transport routes in higher-income countries, have...

Large potential benefits of infrastructure may elude identification and measurement by conventional cost-benefit analysis. Canning and Bennathan estimate social rates of return on general capital, by examining the effect on aggregate output and comparing that effect with the costs of construction