Accounting for Emergent Behavior in Built Environment Planning and Decision-Making

The built environment increasingly involves tightly coupled physical, spatial, logical, and cyber interactions that can generate unexpected emergent behaviors beyond original system designs. These behaviors introduce uncertainty into construction and infrastructure planning and management, often negatively affecting productivity, safety, and resilience. Although emergent behavior is well-established in systems engineering, its systematic consideration in built environment research remains limited, with existing studies relying on ad hoc, reactive approaches rather than proactive modeling and analysis. This study conducts a literature review of construction and infrastructure engineering and management studies alongside foundational systems engineering research on emergence. Based on this synthesis, a formal taxonomy of emergent behavior in the built environment is developed, identifying four distinctive types based on the nature of underlying interactions, level of complexity, and boundaries of information available. Building on this taxonomy, a three-step framework (i.e., classification, operationalization, and implementation) is proposed to guide the systematic identification and analysis of emergent behaviors. To demonstrate practical relevance, the framework is applied to a case study on heavy equipment planning for debris sorting during demolition operations. The case study empirically identified emergent productivity patterns arising from spatial interactions among excavators and quantifies their impacts across different operational stages using real-world, lab-scale simulation. The findings illustrate how emergent behavior can be incorporated into planning decisions to optimize excavator configurations, thereby enhancing operational efficiency and supporting more sustainable demolition practices.