Formalization of construction sequencing rationale and classification mechanism to support rapid generation of sequencing alternatives

Resequencing construction activities is a critical task for project planners for effective project control. Resequencing activities require planners to determine the impact or "role" an activity has on successor activities. They also need to determine the status of activities, i.e., which activities may or may not be delayed. Distinguishing the role and status of activities in turn requires planners to understand the rationale for activity sequences. The current critical path method (CPM) framework, however, represents sequencing rationale using precedence relationships and distinguishes activities only with respect to their time-criticality. Thus, planners find it difficult to keep track of individual sequencing logic, and manually inferring the role and status of activities becomes practically prohibitive in complex project schedules. The research presented in this paper addressed this limitation of the CPM framework by formalizing a constraint ontology and classification mechanism. The ontology allows planners to describe their rationale for activity sequences in a consistent and intuitive way, whereas the classification mechanism leverages the ontology to automatically infer the role and status of activities. The ontology and mechanisms were implemented in a prototype tool. With this tool, users can quickly verify which activities to delay to expedite critical milestone or bottleneck activities, thus making it possible to quickly evaluate and generate sequencing alternatives in CPM-based schedules.