Infrastructure project appraisal is a critical function of public investment management, especially in developing economies where fiscal discipline and institutional capacity are under pressure. This study analyzes the institutional mechanisms of appraisal, focusing on the Development Project Proposal (DPP) system and the role of the Project Evaluation Committee (PEC) as instruments of governance and accountability. The paper identifies recurring challenges such as optimistic costing, weak feasibility studies, and overlapping project scopes by using a qualitative institutional process analysis method. It also highlights the corrective role of appraisal deliberations in safeguarding fiscal credibility and infrastructure quality. The findings emphasize the need to strengthen upstream project preparation, set technical appraisal expertise, and institutionalize feedback loops. Beyond the specific national context, the study contributes to the literature on infrastructure policy by demonstrating how appraisal committees function as essential gatekeepers for sustainable public investment in developing-country contexts.