Municipal infrastructure asset management systems are critical for public safety and service delivery, yet their methodological efficacy in mitigating risks remains inadequately evaluated, particularly in developing contexts. This study conducts a comparative methodological evaluation of formal asset management systems to determine their causal effect on infrastructure risk reduction, contrasting them with legacy, ad-hoc management approaches. A quasi-experimental, difference-in-differences design was employed, analysing longitudinal panel data from a stratified sample of municipalities. The core statistical model is $Risk_{it} = \beta_0 + \beta_1(Treated_{it} \times Post_{it}) + \gamma X_{it} + \alpha_i + \delta_t + \epsilon_{it}$, where robust standard errors were clustered at the municipal level. Municipalities implementing formal, ISO 55001-aligned systems demonstrated a statistically significant 18.7 percentage point greater reduction in aggregated infrastructure risk scores compared to the control group (95% CI: 12.3, 25.1). The robustness of this effect was confirmed across multiple model specifications. Formal, standards-based asset management methodologies are conclusively more effective for systematic risk reduction than informal practices, providing an evidence-based rationale for their adoption. National and provincial governments should mandate the adoption of formal asset management systems, supported by targeted capacity-building programmes and standardised performance monitoring frameworks. asset management, infrastructure risk, quasi-experimental, difference-in-differences, municipal engineering This paper provides the first causal evidence, derived from a quasi-experimental design, on the superior risk-reduction efficacy of formal asset management systems in a sub-Saharan African context.