{ "background": "Municipal infrastructure asset systems in many developing nations face chronic performance deficits, yet evidence-based methodologies for systematic, on-ground diagnostics and optimisation are scarce. Existing evaluations often rely on normative models or aggregated data, lacking rigorous field validation.", "purpose and objectives": "This study aimed to design and implement a randomised field trial to empirically diagnose performance bottlenecks and quantify potential efficiency gains within municipal infrastructure systems. The primary objective was to test a novel intervention protocol for asset management optimisation.", "methodology": "A clustered randomised controlled trial was conducted across multiple municipal jurisdictions. Treatment clusters received a structured diagnostic and optimisation protocol involving condition audits, real-time performance monitoring, and targeted maintenance rescheduling. Control clusters continued with conventional practices. System efficiency was modelled using a multilevel regression: $Y{ij} = \\beta0 + \\beta1T{ij} + \\gamma X{ij} + uj + \\epsilon{ij}$, where $Y{ij}$ is the efficiency score for asset $i$ in cluster $j$, $T{ij}$ is the treatment indicator, and $uj$ are cluster random effects. Inference was based on robust standard errors.", "findings": "The intervention yielded a statistically significant mean efficiency gain of 17.3% (95% CI: 12.1 to 22.5) in treatment clusters compared to controls. The most substantial improvements were observed in water distribution networks and road surface maintenance cycles, where resource utilisation improved markedly.", "conclusion": "The randomised field trial confirms that a structured, data-driven diagnostic protocol can generate significant and measurable efficiency improvements in municipal infrastructure asset management within a sub-Saharan context.", "recommendations": "Municipal authorities should adopt standardised performance diagnostics integrated with real-time monitoring systems. Policy frameworks must be revised to mandate regular, randomised audits for benchmarking and continuous improvement.", "key words": "infrastructure asset management, randomised controlled trial, efficiency optimisation, municipal engineering, field diagnostics, sub-Saharan Africa", "contribution statement