Abstract
{ "background": "Municipal infrastructure asset management in many African contexts relies on reactive, condition-based approaches, leading to inefficient resource allocation and heightened failure risks. A paradigm shift towards proactive, risk-informed diagnostics is required but lacks robust field validation in these settings.", "purpose and objectives": "This study aimed to evaluate the efficacy of a novel risk-based diagnostic framework for municipal infrastructure systems through a randomised field trial. The primary objective was to quantify the reduction in unplanned maintenance events and associated cost variances achieved by the intervention.", "methodology": "A cluster-randomised controlled trial was conducted across 42 municipal asset systems. Intervention clusters received the risk-based diagnostic protocol, which prioritised assets using a Bayesian risk score $Ri = P(Fi) \\times C(Fi | \\theta)$, where $P(Fi)$ is the probability of failure and $C(\\cdot)$ is the consequence function parameterised by $\\theta$. Control clusters continued with standard practice. Primary outcomes were analysed using generalised linear mixed models with robust standard errors.", "findings": "Systems under the risk-based protocol experienced a 34% reduction (95% CI: 22% to 46%) in major unplanned maintenance events per annum compared to control systems. The intervention also significantly reduced the variance in annual maintenance expenditure by 41%, indicating improved budgetary predictability.", "conclusion": "The risk-based diagnostic framework demonstrably enhances the resilience and financial predictability of municipal infrastructure management. It represents a viable, evidence-based alternative to conventional condition-led approaches.", "recommendations": "Municipal engineers and asset managers should adopt probabilistic risk models as the foundation for diagnostic programmes. Policy should mandate risk-based prioritisation in infrastructure investment planning to optimise limited public funds.", "key words": "asset management, risk-based diagnostics, randomised controlled trial, infrastructure resilience, municipal engineering, sub-Saharan Africa", "contribution statement": "This paper provides the first experimental evidence from a randomised field trial on the effectiveness of a Bayesian risk-scoring model for municipal