Distributed coordination of project schedule changes: An agent-based compensatory negotiation approach

In the construction industry, projects are becoming increasingly large and complex, involving multiple subcontractors. Traditional centralized coordination techniques used by the general contractors become insufficient as subcontractors perform most work and provide their own resources. When subcontractors cannot provide enough resources, they hinder their own performance as well as that of other subcontractors and ultimately the entire project. Thus, construction projects need a new distributed coordination approach wherein all of the concerned subcontractors can respond to changes and reschedule a project dynamically. The focus of this research is rescheduling a project in a distributed manner in order to lower the sum of all participating subcontractors' extra costs associated with changes in their resource constraints, subject to the precedence relationships among project activities, without assuming that a central coordinator knows all the information needed for coordination and that subcontractors are benevolent. The challenges are to find a new distributed approach that enables subcontractors to compensate other affected subcontractors for disadvantageous agreements so that it enhances the global outcome while pursuing individual incentives; to identify schedule conflicts, consider alternatives; and resolve schedule conflicts in a tightly coupled network of related activities; and to preserve the work logic and ensure convergence of distributed computation. To meet the challenges, I developed a new distributed coordination framework for project schedule changes (DCPSC) and a novel agent-based compensatory negotiation (ABCN) methodology to enable the framework. The DCPSC-based ABCN methodology has met challenges fully by using novel definitions of utility-based schedule-change options, by employing new multi-linked negotiation protocols based on a shared project plan, and by introducing new mechanisms of directing message-passing based on the Critical Path Method (CPM). In addition to this theoretical work, I designed and implemented a new Java-based multi-agent prototype—distributed subcontractor agent system (DSAS)—to demonstrate the effectiveness of the DCPSC framework through a series of comparison tests, charrette tests, and measurements. DSAS solves the problems successfully. Thus, this research formalizes, implements, and tests the necessary steps to help subcontractors coordinate schedule changes in order to increase the efficiency of their resource use, which in turn enhances successful completion of whole projects.