Mixed methods study design, pre-analysis plan, process evaluation and baseline results of trailbridges in rural Rwanda

We present a study design, pre-analysis plan, process evaluation and baseline results designed to establish the impact of trailbridges on health, education, agricultural and economic outcomes of households in rural Rwanda. This intervention and study is being implemented in communities that face barriers to socioeconomic development through periodic isolation caused by flooding. We describe a mixed methods approach to measure the impacts of these trailbridges on outcomes at the village level. The study is anchored on a stepped-wedge randomized controlled trial (RCT) implemented in 147 sites: 97 phased-in intervention sites and 50 long-term control sites. These sites are being monitored in four annual waves comprising of a baseline period and three subsequent follow-up waves. We will supplement the RCT with three sub-studies. First, we are investigating the role of weather events and streamflow variability on temporal and spatial bridge use patterns among intervention sites. We will then find the relationship between the weather events, streamflow and bridge use from motion-activated cameras installed in intervention sites. Secondly, we are following 42 markets serving study sites to investigate the impact of the trailbridges on the market prices of key goods including crops, livestock and agricultural inputs. Lastly, we are following 30 villages that are more distant from the river crossings to determine the spatial extent of the trailbridge impacts. Our study will advance knowledge by generating new data on the impact of rural infrastructure and providing the opportunity to explore a range of outcomes for future evaluation of infrastructure in low- and middle-income countries. We will enable an outcomes-based funding model that ties implementer payments to demonstrated positive impacts of these trailbridges. Furthermore, we will identify cost-effective, easily assessed measures that are highly correlated to the economic and health benefits of the intervention. These measures may then be used by a portfolio of interventions across multiple geographies without always requiring complex trials.