From Safety Climate to Proactive Safety Behavior: The Cross-Level Mediating Role of Leader–Member Exchange in Construction Workers’ Safety Citizenship Behavior

Construction projects are high-risk environments characterized by workforce mobility, fragmented operations, schedule pressure, and multilayer subcontracting. This study examines how team safety climate and workgroup-shared perceived organizational safety priority (shared POSP) are associated with construction workers’ safety citizenship behavior (SCB), and whether leader–member exchange (LMX) serves as a cross-level relational mechanism. Survey data from 391 frontline workers nested within 73 workgroups in Chinese building construction projects were analyzed using Bayesian multilevel structural equation modeling. SCB showed substantial between-workgroup variance (ICC(1) = 0.524). Team safety climate had no statistically credible total association with SCB (posterior mean = −0.018, 95% Bayesian credible interval (BCI) [−0.554, 0.507]), but was positively associated with LMX (0.368, [0.115, 0.620]); LMX was positively associated with SCB (1.373, [0.693, 2.126]). The indirect association through LMX was statistically credible (0.492, [0.124, 1.010]), whereas the residual direct association was negative (−0.523, [−1.075, −0.021]). Shared POSP showed a positive direct association with SCB (0.610, [0.158, 1.046]). The findings indicate a competitive mediation pattern and highlight the importance of combining safety-priority signals with supportive leader–worker exchange.