Methodological Evaluation and Reliability Assessment of Senegal's Transport Maintenance Depot Systems: A Difference-in-Differences Approach

{ "background": "Transport infrastructure maintenance is critical for economic development, yet systematic evaluations of depot system reliability in West Africa are scarce. Existing assessments often lack robust counterfactual analysis, limiting causal inference on system performance.", "purpose and objectives": "This short report aims to methodologically evaluate the reliability of transport maintenance depot systems using a quasi-experimental design. The objective is to quantify the causal effect of a centralised management intervention on depot operational uptime.", "methodology": "A difference-in-differences model was employed, comparing treatment and control depot groups before and after the intervention. The core estimating equation is $Y{it} = \\beta0 + \\beta1 \\text{Treat}i + \\beta2 \\text{Post}t + \\delta (\\text{Treat}i \\times \\text{Post}t) + \\epsilon{it}$, where $Y{it}$ is the monthly operational uptime percentage. Inference is based on cluster-robust standard errors at the depot level.", "findings": "The intervention yielded a statistically significant positive effect. The estimated coefficient $\\hat{\\delta}$ was 7.3 percentage points (95% CI: 2.1 to 12.5), indicating a substantial improvement in system reliability for treated depots relative to controls.", "conclusion": "The difference-in-differences approach provides a rigorous methodological framework for evaluating infrastructure maintenance systems. The results demonstrate that targeted managerial interventions can significantly enhance depot reliability.", "recommendations": "Adopt the quasi-experimental methodology for future infrastructure performance audits. Policy should focus on scaling the centralised management model to depots with historically low uptime, prioritising those in the control group that showed no improvement.", "key words": "infrastructure maintenance, reliability engineering, quasi-experimental design, causal inference, transport systems", "contribution statement": "This report provides the first application of a difference-in-differences model to assess transport maintenance systems in the region