Critical Activity Analysis in Precedence Diagram Method Scheduling Network

Abstract

Pecedence Diagram Method (PDM) scheduling network introduced three alternative relationships, i.e., finish-to-finish, start-to-start, and start-to-finish, with positive time lag factors between project tasks. PDM with its new relationships has provided more flexible realistic project representation in schedule networks. However, the new relationships of PDM will change the basic concept of critical activities and critical path. Changing the duration of some critical activity in PDM in order to reduce the project duration has anomalous effects on project duration. In this study we proposed classification of critical activity effects on project duration in PDM. In addition, we determined the maximum amount of time by which changing the duration of a critical activity will have anomalous effect on project duration. Therefore, the project managers will clearly distinguish the behavior of each critical activity on critical path, and they can change the project duration by shortening/lengthening activities based on project budget and project deadline.