Exploring socioeconomic and environmental impacts of road infrastructure development in Sub-Saharan Africa: A systematic literature review

While road infrastructure expansion continues transforming Sub-Saharan Africa, research remains fragmented between socioeconomic and environmental impact assessments. Through a systematic review of 255 peer-reviewed articles from 6,189 papers (1984-2024) examining road development impacts, we reveal patterns in research focus, methodological approaches and road development impacts. Approximately 58% of published studies on road impacts examined socioeconomic impacts, 37% investigated environmental effects, while only 5% investigated both socioeconomic and environmental impacts simultaneously. Geographically, most studies were conducted in five countries (Ethiopia, South Africa, Nigeria, Kenya, and Tanzania), with 78% of these studies published after 2014. Furthermore, our analysis found a significant relationship between foreign direct investment (FDI) and environmental degradation, with countries experiencing a 34% increase in observed negative environmental road impacts for each standard deviation increase in FDI (β = 0.34, p < 0.05). This effect tended to be particularly strong in countries with weaker environmental governance. Moreover, countries with higher Human Development Index (HDI) scores demonstrated 28% fewer negative environmental impacts, suggesting development status significantly influences environmental management capacity. Consequently, we suggest assessing road effects from an interdisciplinary perspective to better understand road-induced tradeoffs and offer informed, evidence-based planning for road infrastructure development that minimizes environmental costs and maximizes socioeconomic benefits.