Why lean construction falters in megaprojects: A systemic diagnosis of interdependent barriers using fuzzy DEMATEL

• Fuzzy DEMATEL maps interdependent barriers to lean construction in megaprojects • Organizational, stakeholder, and financial barriers drive process and technology issues • High employee turnover and insufficient training are key intervention points • Visual causal diagrams enable targeted barrier mitigation strategies • Systems approach reveals root causes requiring priority intervention Lean Construction (LC) is increasingly recognized as a vital strategy for enhancing efficiency, minimizing waste, and maximizing value in complex megaprojects, where systemic inefficiencies carry significant economic and operational consequences. Yet, LC adoption remains hindered by deeply rooted, interdependent barriers spanning organizational culture, stakeholder alignment, process design, financial constraints, and technological readiness. Addressing a critical gap in the current literature, this study employs a systems-thinking lens to map and analyze the causal relationships among LC barriers in megaproject contexts. Through an integrated methodology, combining a systematic literature review, expert validation, and the Fuzzy DEMATEL (FDEMATEL) technique, the research models the dynamic, uncertain interplay among 24 sub-barriers, categorized into five core groups: Organizational & Attitudinal (OAB), Stakeholder (SB), Process (PB), Financial (FB), and Technological & Knowledge Barriers (TKB). Findings reveal that OAB, SB, and FB are primary drivers, exerting a strong influence over PB and TKB. Key leverage points include “high employee turnover (SB7),” “insufficient training (OAB5),” “slow decision-making (OAB4),” “inadequate digital tools (TKB2),” and “weak performance measurement (PB3).” Visual causal maps and influence matrices provide practitioners with a prioritization framework for targeted interventions. The study underscores that sustainable LC adoption requires tackling root organizational and financial barriers to prevent downstream inefficiencies. Beyond empirical insights, this research offers a replicable, systems-based methodology for diagnosing complex implementation challenges, theoretically and practically contributing to more resilient, leaner megaproject delivery worldwide.