How can improved roads change peoples’ lives? How much do people benefit from road projects? Answering these seemingly simple questions is, in fact, much trickier than it appears.
We recently concluded an impact evaluation
to measure the socio-economic impacts of World Bank-financed municipal road improvements on poor rural households in the state of Tocantins, Brazil. After 10 years of study, what were the results and lessons learned? And how did we go about conducting the evaluation?
followed a methodology traditionally used in impact evaluations in the social sector and was based on a precedent in Vietnam. Throughout the state, one of the least-developed and least-populated in Brazil, most municipal roads are unpaved with inadequate maintenance. The World Bank’s municipal roads project helped construct 700 concrete bridges and 2,100 culverts crossing rivers and streams, providing year-round access to remote populations that once couldn’t access municipal centers during rainy season.
The anticipated result chain of the project was as follows: improvement of physical accessibility would contribute to increase travel demand to markets, schools and health services. This would, in turn, contribute to improved education, better health and increased business opportunities. Finally, it would result in long-term household income growth.
Our study aimed at measuring these impacts through a “difference in differences with matching,” a method that compares a treatment group (population benefiting from the interventions) and a control group (population that does not), while ensuring similar socio-economic characteristics (or comparability) between groups. An “instrumental variables estimator” was then used to confirm the robustness of the results.
The results show positive socio-economic impacts to rural residents, as well as provides for several policy implications: