Effects of the last planner system on social networks among construction trade crews

Lean system thinking concerning the mechanics of construction production systems suggests that the Last Planner System (LPS) improves workflow by creating pull flow and by filtering work packages for maturity. However, empirical evidence shows that even where implemented only partially, LPS can still improve workflow. The authors hypothesize that the LPS engenders a social network among the subcontractors, which enhances coordination. Twelve residential construction projects were studied using action research over periods from 7 to 16 months to measure the impact of the LPS on social networks. Centrality degrees of trade crews rose significantly and the number of active essential communication channels roughly doubled when comparing projects with low and high planning best-practice index scores, showing that where the LPS is more thoroughly implemented, social networks are strengthened. The results contribute new understanding of the LPS and its mechanism. The LPS not only functions on the technical level to improve production control, it also has social impact, building relationships among construction teams that can contribute to improved coordination.