{ "background": "Transport maintenance depot systems in developing nations face complex, multi-faceted risks that challenge conventional risk assessment frameworks. Existing methodologies often fail to adequately capture the hierarchical nature of operational data and the inherent uncertainty in sparse datasets typical of such contexts.", "purpose and objectives": "This case study presents a methodological evaluation of a novel Bayesian hierarchical model designed to quantify risk reduction within transport maintenance depot systems. The objective is to demonstrate a robust framework for integrating disparate data sources to inform infrastructure management decisions.", "methodology": "A case study methodology was employed, applying a Bayesian hierarchical model to operational and maintenance data from a network of depots. The core model structure is $y{ij} \\sim \\text{Normal}(\\alphaj + \\beta X{ij}, \\sigmay^2)$, with $\\alphaj \\sim \\text{Normal}(\\mu{\\alpha}, \\sigma_{\\alpha}^2)$, where $i$ indexes observations and $j$ indexes depots. Inference was performed using Markov chain Monte Carlo sampling, with posterior distributions summarised by their median and 95% credible intervals.", "findings": "The model successfully quantified the reduction in systemic risk following targeted interventions. A key finding was a median posterior estimate of a 34% reduction in high-priority failure risk, with the 95% credible interval ranging from 28% to 41%. The hierarchical structure revealed significant depot variability, identifying specific operational themes, such as spare parts logistics, as dominant risk drivers.", "conclusion": "The Bayesian hierarchical model provides a statistically robust and operationally insightful framework for measuring risk reduction in complex, real-world maintenance systems. It effectively handles data limitations and uncertainty, offering a superior alternative to deterministic models.", "recommendations": "Adopt the proposed Bayesian hierarchical framework for ongoing risk monitoring and resource allocation in transport asset management. Future work should focus on integrating real-time sensor data to transition from periodic to continuous risk assessment.", "key words": "Bayesian inference, hierarchical modelling