<![CDATA[The Kucing Liar Fan 7 project is an underground ventilation construction project within the Central Services Division of PT Freeport Indonesia. The problems arose not from a single cause but from the interaction of management, construction method, material availability, people and communication, equipment, and the underground working environment. This study aims to identify and evaluate the key lessons learned from the Kucing Liar Fan 7 project, determine how these lessons can be institutionalized through a Project Management Office (PMO), and develop an implementation roadmap to improve future construction performance. A mixed-method approach was used, combining a five-point Likert questionnaire distributed to 27 project stakeholders across six factors (Management, Method, Material, People, Environment, Equipment) with historical project data, interviews, observation, and two sessions of Focus Group Discussion (FGD). The questionnaire results were analysed using mean scores, Relative Importance Index (RII), Cronbach's alpha, and Pareto analysis. The analysis identified Management, Method, Material, People, and Environment as the prioritized factors, jointly accounting for 84.93% of the cumulative relative importance, with root causes concentrated in design readiness, change control, material planning, communication, and constrained underground working space. The lessons learned were translated into a Lesson Learned Register and a phased Controlling PMO implementation roadmap consisting of organizational assessment, pilot implementation, organizational integration, and continuous improvement. The proposed PMO does not replace the existing balanced-matrix structure but strengthens governance, standardization, coordination, monitoring, and knowledge management to reduce the recurrence of delays in future underground ventilation construction projects.]]>
