{ "background": "Maintenance depot systems are critical for transport infrastructure sustainability, yet their operational efficiency in developing contexts is poorly quantified. Existing evaluations often lack the statistical rigour to account for hierarchical data structures inherent in such systems.", "purpose and objectives": "This case study provides a methodological evaluation of applying multilevel regression modelling to measure efficiency gains within a national transport maintenance framework. It aims to demonstrate the model's utility in isolating depot-level performance from systemic and regional variables.", "methodology": "A case study analysis was conducted using operational data from a stratified sample of regional and district-level depots. The core methodological approach employed a three-level linear mixed model: $y{ijk} = \\beta0 + \\beta X{ijk} + u{k} + v{jk} + e{ijk}$, where $uk$ and $v{jk}$ are random intercepts for region and district, respectively. Inference was based on robust standard errors to account for heteroscedasticity.", "findings": "The multilevel model revealed that depot-level interventions accounted for approximately 22% of the observed variance in task completion rates, after controlling for regional resource allocation. A significant positive fixed effect was identified for integrated inventory systems ($\\beta = 0.41$, 95% CI [0.28, 0.54]), indicating a strong association with efficiency.", "conclusion": "The methodology successfully disentangles depot-specific efficiency gains from broader systemic influences, offering a more nuanced analytical tool than conventional single-level regression. It confirms the importance of hierarchical modelling for accurate performance attribution in decentralised engineering systems.", "recommendations": "Adopt multilevel regression as a standard analytical framework for benchmarking depot performance. Prioritise the rollout of integrated inventory management systems, as identified by the model, to drive measurable efficiency improvements.", "key words": "multilevel modelling, infrastructure maintenance, efficiency analysis, regression analysis, depot management, Senegal", "contribution statement": "This study presents a novel application of hierarchical