A survey of impact evaluations of infrastructure projects, programs and policies

This paper surveys the main lessons from impact evaluations of infrastructure projects, programs and policies relevant to policymakers. In the process, however, it also reveals some major research gaps of relevance to academics. After a brief discussion of the motivation for the explosion of the demand for impact evaluations, it starts with some sometimes underestimated lessons for infrastructure specialists from theoretical experiment. The main focus of the paper is, however, the impact evaluations derived from experimental and quasi-experimental techniques. It covers energy, water and sanitation as well as the various transport subsectors (ports, railways, rural roads and highways). The main value added of the survey may be to show that despite the relatively modest number of published evaluations concluded in infrastructure as compared to health or education for instance, there is a growing coverage of the sector in evaluation efforts. The survey also offers an opportunity to get a sense of the creativity of researchers conducting these evaluations. It summarizes the main questions asked, the main techniques used and when available the results available. It concludes with a discussion of some of the limitations of evaluations in the context of infrastructure interventions.