{ "background": "Municipal infrastructure asset management in many developing contexts is hampered by reactive, ad-hoc maintenance strategies. Systematic, data-driven diagnostics for prioritising risk reduction interventions are often absent, leading to inefficient resource allocation and accelerated asset deterioration.", "purpose and objectives": "This case study evaluates a novel diagnostic protocol for infrastructure risk reduction. Its primary objective is to measure the causal effect of implementing structured asset condition and criticality assessments on planned, preventative maintenance expenditure within municipal budgets.", "methodology": "A randomised field trial was conducted across 24 municipalities. Clusters were randomly assigned to treatment (implementation of the diagnostic protocol) or control (continued conventional practice). The primary outcome, the proportion of annual maintenance budget allocated to planned interventions, was analysed using a linear mixed model: $Y{ij} = \\beta0 + \\beta1 Tj + \\gamma X{ij} + uj + \\epsilon{ij}$, where $Tj$ is the treatment assignment for cluster $j$, with robust standard errors clustered at the municipal level.", "findings": "Municipalities applying the diagnostic protocol demonstrated a statistically significant increase in the proportion of budget directed to planned maintenance. The estimated treatment effect was 17.3 percentage points (95% CI: 11.1 to 23.5). This reallocation was primarily sourced from reductions in emergency repair funding.", "conclusion": "The structured diagnostic protocol effectively shifts municipal engineering practice from reactive to proactive asset management by providing a clear, evidence-based framework for prioritising infrastructure investments.", "recommendations": "National and local governments should integrate structured diagnostic protocols into formal asset management policy. Capacity building in data collection and risk-based analysis is essential for sustained implementation.", "key words": "asset management, randomised controlled trial, infrastructure risk, maintenance planning, municipal engineering", "contribution statement": "This study provides the first experimental evidence from a low-income country demonstrating that a structured diagnostic protocol can causally reallocate municipal infrastructure expenditure towards preventative, risk-re