Randomised Field Trial of Maintenance Depot System Reliability in Tanzanian Transport Networks

{ "background": "Maintenance depot systems are critical for the reliability of transport infrastructure, yet their performance in sub-Saharan contexts is under-studied. Current evaluations often rely on retrospective, non-experimental data, limiting causal inference on system efficacy. ", "purpose and objectives": "This study aimed to implement and evaluate a novel randomised field trial methodology to measure the operational reliability of road maintenance depot systems, with the objective of generating robust, experimental evidence on causal factors affecting depot performance. ", "methodology": "A randomised controlled trial was conducted across a network of depots. Depots were randomly assigned to an intervention group receiving enhanced logistical protocols or a control group maintaining standard practice. System reliability was measured as the time-to-failure of depot output against specified performance thresholds. The primary analysis used a Cox proportional hazards model: h (t|X) = h0 (t) \ (\1 X1 + \2 X2), where X1 represents the intervention and X₂ a depot size covariate. ", "findings": "Depots in the intervention group demonstrated a 40% lower hazard of performance failure compared to control depots (hazard ratio = 0. 60, 95% CI: 0. 48 to 0. 75). The median time-to-failure increased from 42 days to 68 days under the enhanced protocol. Uncertainty was quantified using robust standard errors clustered at the regional level. ", "conclusion": "The randomised field trial proved a viable method for rigorous, causal evaluation of engineering maintenance systems in this context. The intervention significantly enhanced depot reliability. ", "recommendations": "Transport authorities should adopt principles of experimental design for system evaluations. The specific logistical protocols tested here warrant broader implementation and scaling. ", "key words": "infrastructure maintenance, randomised controlled trial, system reliability, transport engineering, field experiment", "contribution statement": "This paper provides the first application of a randomised field trial to evaluate transport maintenance depot systems in sub