Formalizing a path-float-based approach to determine and interpret total float in project scheduling analysis

Abstract

The classic critical path method (CPM) determines total float (TF) for each individual activity by performing forward pass and backward pass analyses. A comprehensive literature review has shown that TF is the most crucial attribute of a scheduled activity, and plays a fundamental part in advanced scheduling research. This research proposes a simplified version of CPM, called path-float-based critical path method (PFCPM), which determines TF based on identification of path float (PF) instead of entailing a backward pass analysis in the classic CPM. Analytical proof is provided and step-by-step application procedures are generalized. Then, PFCPM application examples are given based on two demonstration projects represented in activity-on-node (AON) and precedence diagram method (PDM) networking formats, respectively. Results are compared with the classic CPM for cross-validation. The newly proposed PFCPM enhances CPM-based scheduling through circumventing the backward pass analysis in deriving TF based on PF; helping researchers and practitioners interpret the TF ownership issue and account for changes on TF as a result of activity delay by relating TF with PF; and laying a theoretical foundation for further research into advanced construction planning methods such as resource loading, time–cost tradeoff and risk analysis.