Maintenance Management Framework for Reduction of Cost and Time Overruns in Government and Donor-Funded Road Maintenance Projects: A Case of TANROADS, Tanzania

Road maintenance projects implemented by the Tanzania National Roads Agency (TANROADS) under government and donor financing frequently exceed their approved budgets and completion dates. In 2024/2025, only 49.58% of the planned maintenance length was achieved, and about 67% of the approved budget was received, while no integrated tool existed to predict and control overruns at the project level. This study identified the causes of cost and time overruns, formulated and validated a predictive maintenance management model, and designed a management framework. A mixed-methods design combined a questionnaire survey of 252 professionals, document review of 40 maintenance projects, 24 key-informant interviews, 30 field observations and an expert validation checklist completed by 25 experts. Causes were ranked using the Relative Importance Index (RII), and a multiple linear regression model was calibrated on 176 observations and checked on 76 hold-out observations and ten sample projects. Contractor cash-flow constraints (RII = 0.8746), material price fluctuation (RII = 0.8627), delayed government budget release (RII = 0.8413), inadequate budget allocation (RII = 0.8254) and incomplete design or scope changes (RII = 0.8183) were the leading causes. The model explained 88.52% of the variance in cost overrun (R² = 0.8852; adjusted R² = 0.8804; F = 185.00; p < 0.001). Financial flow (β = 24.38), planning and design deficiencies (β = 19.64) and procurement delays (β = 15.15) had the largest effects. Applied to ten projects, the six management factors predicted actual overruns with a mean absolute error of 1.47 percentage points and a mean absolute percentage error of 3.42%. The resulting framework links diagnosis, prediction, monitoring and corrective action, and indicates that TANROADS should prioritise payment-flow reform and design completeness.