Key constraints analysis with integrated production scheduler

Project delays due to late availabilities of resource and information (RI) prerequisites are one of the major threats to construction management. It is desirable to avoid such delays through better means of constraint management. With most contemporary planning methodologies and tools, it is generally difficult to represent many hidden flow constraints in a construction work plan. However, evaluating the impact of flow constraints is crucial in determining their criticalities, based on which the flow constraints may be prioritized and consequently resolved to minimize project delays. Due to the fact that limited resources are often shared among various trades, it may not be practical to resolve all the constraints simultaneously so that a tradeoff is inevitable, which suggests that management should focus on the most important ones termed as key constraints (i.e., those directly contributing to project delays). This paper presents a methodology that augments the traditional critical path method with RI availability constraints to analyze the causes of delays and locate the key constraints binding on project completion without ambiguity based on the principles of the theory of constraints. The methodology of key constraint analysis has been implemented with the integrated production scheduler, a constraint-based scheduling tool which facilitates the modeling, analysis, and management of constraints at the production planning level. An illustrative example is depicted to demonstrate how the proposed methodology works.