The present paper deals with the reevaluation of design stresses and assessment of safety margins available for an underground reinforced cement concrete (RCC) duct. For stress analysis, a two-dimensional mathematical model has been adopted to appropriately represent the structure. The structure has been analyzed for both static and seismic loads. The seismic analysis has been carried out for site-specific response spectra. The design checks have been performed using available international standards and, accordingly, the safety margins have been evaluated. The structure has been found to possess sufficient safety margins under all the postulated design loadings. The seismic reassessment methodology conforms to the available international standards.