Determinants of Urban Public Transportation Costs in a Rapidly Urbanizing African City: Evidence from Adama, Ethiopia

Urban transport affordability remains a major policy concern in rapidly urbanizing Sub-Saharan African cities. Despite extensive theoretical work on transport economics, empirical evidence quantifying structural determinants of public transportation cost in secondary African cities remains limited. This study examined the influence of economies of scale, road maintenance and upkeep, fuel and energy subsidy, and fare infrastructure integration on public transportation cost in Adama City, Ethiopia. A cross-sectional study was conducted among transport associations, driver training institutions, and regulatory officials (n = 181; response rate 88%). Data were analysed using multiple linear regression. The regression model was statistically significant (F (4,176) = 63.42, p < 0.001) and explained 59% of the variance in transportation cost (R² = 0.59; adjusted R² = 0.57). Economies of scale showed the strongest inverse association (β = −0.41, p < 0.001), followed by fuel and energy subsidy (β = −0.29, p < 0.01), road maintenance (β = −0.18, p < 0.05), and fare infrastructure integration (β = −0.16, p < 0.05). Structural and policy-level interventions targeting system scale, infrastructure quality, and coordinated fare systems may substantially reduce urban transport costs. The findings contribute empirical evidence from Ethiopia to the broader literature on urban transport economics.