A Randomised Field Trial for Risk-Based Diagnostics of Municipal Infrastructure Asset Systems in Kenya

{ "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) \× C(Fi | \θ), where $P(Fi)$ is the probability of failure and C(\·) is the consequence function parameterised by \θ. 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