Case Study
In practice, project managers carefully manage slack on sensitive resource limited projects. If possible, they will add slack at the end of the project by committing to a completion date that goes beyond the scheduled date. For example, the plans say the project should be completed on April 1, although the official completion date is May 1. Other managers take a more aggressive approach to managing slack within the schedule. They use an early start schedule and prohibit use of slack on any activity or work package to be used unless authorized by the project manager. Progress by percent complete and by remaining times are reported so that succeeding activities can start ahead of schedule. This ensures that the time gained is used to start a succeeding activity earlier and time is not wasted. The overall intent is to create a save slack as a time buffer to complete the project early or to cover delay problems that may creep up on critical activities or paths.
Eliayahu Goldratt, who championed the "theory of constraints' in his popular book the goal, advocates an alternative approach to managing slack. He has coined the term "critical chain" to recognize that the project network may be constrained by both resource and technical dependencies. Each type of constraint can create task dependencies, and technical dependencies. Each type of constraint can creat task dependencies, and in the case of resource constraints, new task dependencies, and in the case of resource constraint, new task dependencies can be created! Remember how resource constraints shifted the critical path? If not, visit exists on the project. Chain is used instead of path, since the latter tends to be associated with just technical dependencies not resource dependencies. Goldratt uses the critical chain concept ot develop strategies for accelerating the completion of projects. These strategies are based on his observation about time estimates of individual activities.
Answer Questions below
a) Would the outcome of the scheduling process have been any different had the critical chain approach been used?
b) Would the critical chain approach have been easier to implement than the traditional method of developing the network first followed by applying resources?
c) What are your impressions of the overall merit of the critical chain approach as compared to the traditional method?