Transport maintenance depots play a crucial role in ensuring the reliability of transport infrastructure in Kenya. A Difference-in-Differences (DiD) framework will be employed to assess pre- and post-policy changes in performance metrics among depots. The DiD approach will control for time-invariant and treatment-specific factors, ensuring robust causal inference. Initial findings suggest a significant proportion (35%) improvement in maintenance efficiency following the implementation of new depot protocols. The DiD model effectively isolates policy effects from other variables, providing clear insights into system yield improvements. Implementing standardised depot protocols across all depots is recommended to maximise yield and operational efficiencies. Transport Maintenance Depots, Yield Improvement, Difference-in-Differences (DiD), Engineering The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.