Unsafe behaviors in workers at heights: A spacetime-based coupling analysis method and its safety implications

Unsafe behaviors among construction workers are a major cause of safety incidents. Existing studies often focus on single or static analyses, limiting their ability to reveal behavior interrelationships and dynamic impacts. Spacetime coupling analysis can identify high-risk behavior combinations and pinpoint hazardous scenarios. This study extracts unsafe behaviors and their associated temporal and spatial occurrences from construction safety incident reports. Using complex network theory, bipartite networks of time-behavior and space-behavior relationships were constructed, and a coupling network of unsafe behaviors was generated through their projections. To enhance accuracy and adaptability, the gray correlation analysis (GRA) method was improved by introducing temporal distribution as weights, dynamically adjusting relational coefficients to measure spacetime coupling degrees. This approach leverages the temporal patterns of unsafe behaviors to better capture their dynamic evolution, but spatial distributions were not used as weights due to their relatively static nature in the context of this analysis. The analysis revealed clear temporal and spatial patterns of unsafe behaviors. Early mornings saw frequent scaffold-related violations and missing helmets due to low safety vigilance. Midday incidents involved unstable supports and uncleaned lifting paths, and afternoons showed increased electrical hazards. In the evening, fall-related behaviors rose with worker fatigue. Spatially, high-risk behaviors clustered at floor edges, exterior walls, and hoisting zones, highlighting critical areas for intervention. This study contributes a novel dynamic analysis framework that integrates complex network modeling and an enhanced GRA method, offering new insights into behavior interactions and enabling data-driven safety interventions. These results support precise management strategies for high-risk spacetime conditions and multibehavior coordination, providing a scientific basis for improving construction safety.