Municipal infrastructure asset management in many developing urban contexts is hampered by inconsistent methodologies for evaluating system performance and optimising resource yield. This creates significant inefficiencies in service delivery and capital planning. This policy analysis aims to methodologically evaluate and compare asset management systems, with the objective of quantifying yield improvements through a structured, randomised field trial. It seeks to identify the most effective procedural framework for municipal engineering operations. A randomised controlled trial was implemented across multiple municipal jurisdictions. Asset systems were assigned to treatment and control groups. The core yield optimisation was modelled using a fixed-effects panel regression: $Y_{it} = \beta_0 + \beta_1 T_{it} + \alpha_i + \epsilon_{it}$, where $Y_{it}$ is the yield metric for system $i$ at time $t$, and $T_{it}$ is the treatment indicator. Robust standard errors were clustered at the municipal level. The intervention group demonstrated a statistically significant mean yield improvement of 18.7% (95% CI: 14.2, 23.1) relative to the control. The primary mechanism for this gain was the standardisation of condition assessment protocols and predictive maintenance scheduling. The trial provides robust evidence that adopting a structured, methodologically rigorous asset management system substantially enhances the functional yield of municipal infrastructure networks. Policy should mandate the adoption of the evaluated methodological framework, including standardised data collection and the use of predictive analytics, within municipal engineering departments. Capacity building in these techniques is essential for sustained implementation. asset management, infrastructure, randomised trial, yield optimisation, public works policy, maintenance planning This study provides the first experimental evidence from a large-scale field trial on the efficacy of structured asset management methodologies for improving infrastructure yield in a sub-Saharan urban context.