The Six Practice: integrating flow and leadership in production planning and control

Large construction projects are increasingly characterized by complexity, fragmented organizational structures, and dynamic boundary conditions. Despite the use of detailed schedules and established Lean planning methods, many projects experience persistent gaps between planned targets and actual execution. Deviations are often detected late, addressed locally, or escalated informally, limiting the ability of project organizations to respond effectively. This paper presents a practice-based case study examining the development and application of an integrated flow and leadership approach, here referred to as The Six Practice. The Six Practice integrates project-level production planning and control with line-level execution and leadership systems through cascaded structures that link decisions about what should be delivered and when with decisions about who executes the work and how resources are mobilized. Rather than relying on stable standards, the approach addresses dynamic target states and treats deviations as signals for escalation, decision-making, and learning. Using the Riyadh Metro project as the primary case, the study illustrates how The Six Practice supported early deviation detection, structured escalation, and coordinated action across organizational boundaries. The findings contribute to Lean Construction research by extending existing planning and control concepts toward an integrated, deviation-based and leadership-oriented approach suitable for complex project environments.