A heuristic method to determine optimum degree of activity accelerating and overlapping in schedule compression.

Schedule compression is an attempt to reduce project durations for early delivery, or to catch up on occurred delays. This is usually performed using 'crashing', 'overlapping' and 'substitution' of activities. 'Crashing' is shortening task duration by adding more resource hours. 'Substitution' is changing the method or tool by which the activity is performed. 'Overlapping' is performing sequential activities in parallel. Few studies can be found in the literature that compare costs and benefits of each technique and recommend the optimum combination of these techniques in project schedules. In fact, the implications of each technique are inherently different since crashing and substitution impose extra cost whereas overlapping adds the risk of changes and rework. Therefore, it is a challenge to develop a reliable analytical tool for performing time-cost trade-offs using the three methods. There are also few studies in the literature to propose a practical method for performing schedule compression by combining these techniques. The purpose of this paper is to discuss these schedule compression techniques in detail, and present and validate a heuristic method to perform the combination of crashing, overlapping and substitution in a project schedule, to reach the maximum benefit while meeting the project target dates. [ABSTRACT FROM AUTHOR]