Abstract
{ "background": "Randomised field trials (RFTs) are an established methodology for evaluating engineering safety interventions, yet their application and methodological rigour in low-resource infrastructure settings, such as transport maintenance depots, remain under-examined.", "purpose and objectives": "This study aimed to methodologically replicate a prior RFT designed to measure risk reduction in depot systems. The primary objective was to evaluate the feasibility and validity of the original trial's design and measurement protocols within the Kenyan context.", "methodology": "A replication RFT was conducted across multiple public transport maintenance depots. The intervention, a structured hazard reporting and rectification protocol, was randomly assigned. Risk levels were quantified using a composite safety score. The primary analysis employed a linear mixed-effects model: $Y{ij} = \\beta0 + \\beta1 T{ij} + ui + \\epsilon{ij}$, where $ui$ represents depot-level random effects. Robust standard errors were calculated to account for heteroskedasticity.", "findings": "The replication revealed significant methodological challenges in protocol adherence, leading to high attrition in the treatment group. Consequently, the estimated treatment effect ($\\beta1 = 2.4$, 95% CI [-0.8, 5.6]) was statistically non-significant. A key theme from process evaluation was the critical role of mid-level management buy-in for intervention fidelity.", "conclusion": "The original RFT methodology proved difficult to implement with fidelity in the study context. Non-significant results are likely attributable to implementation failure rather than intervention ineffectiveness, highlighting a key limitation of directly transferring experimental designs.", "recommendations": "Future depot safety trials should incorporate a pilot phase to adapt protocols to local organisational structures and include explicit strategies to secure managerial engagement to mitigate attrition.", "key words": "randomised field trial, replication study, maintenance depot, safety engineering, risk reduction, implementation fidelity", "contribution statement": "This study provides the first