Activity Criticality Index Assessment Using Critical Path Segment Technique and Interactive Simulation Pei TANG 1 and Amlan MUKHERJEE 2 1 Ph.D. Candidate, Department of Civil and Environmental Engineering, Michigan Technological University, Houghton, MI 49931, United States. E-mail: ptang@mtu.edu. 2 Associate Professor, Department of Civil and Environmental Engineering, Michigan Technological University, Houghton, MI 49931, United States. E-mail: amlan@mtu.edu. ABSTRACT Critical Path Method (CPM) is the most widely used project scheduling tool. How- ever, CPM tools are limited as a project management method as they cannot be used to track and update the schedule as construction progresses. Often, during construc- tion, activities are interrupted due to impacts of uncertain events like severe weather and unforeseen harsh geological conditions, resulting in altered critical paths. From a project management perspective, this means that given uncertain conditions, some non-critical activities have a likelihood of becoming critical during the project execu- tion and vice versa. Therefore, the objective of this paper is to identify the changes of activities’ criticality during the construction process. It is assumed that an activity’s probability of being critical tends to be stable during the construction given a construc- tion management strategy. The critical path segment (CPS) technique and interactive simulation are coupled to capture the changes in an activity’s criticality for a given strategy. The research uses the CPS technique to schedule and simulate a highway reconstruction project repeatedly using different strategies. For each simulation trial, the changes in the critical path are recorded to identify the criticality of each segment. The significance of this research is that it applies the CPS technique within a dynam- ic environment and presents a general method to predict the likelihood of an activity becoming critical during the construction process. INTRODUCTION The construction industry has difficulties with using Critical Path Method (CPM) as a project control tool. Traditionally, an activity is identified as either critical or non-critical only at the planning stage, which has limited the ability of CPM tools to 1094 Construction Research Congress 2012 © ASCE 2012