by Hadley Jones
Published on 21 August 2014
Ever since the first project manager experimented with a spreadsheet, people have been padding task estimates with "safety margins." In the world of critical paths and PERT charts, it's understandable. The order of the tasks is what counts and rigid scheduling is what keeps things in order. Or at least, that's the theory. However, from this point of view, time can't be saved if one task finishes early. That extra time is unavailable for use elsewhere.
Critical Chain Project Management (so that's CCPM with 'Chain' instead of 'Path') turns this situation around. It makes task start times flexible and aims for balanced loading of resources. The duration estimates in CCPM are reduced by half for the individual tasks. The extra time generated is then made available to the project as a whole. Sciforma is a project management app with this functionality built in, and it also handles Waterfall and Agile project management methodologies too. An add-on module is available for Microsoft Project to give it CCPM capability.
CCPM is the brainchild of Dr Eli Goldratt. He saw how many projects under-delivered while overstepping both budgets and schedules. Traditional project management methods too often encouraged a waste of resources due to:
Goldratt's big insight was that projects are in truth planned and executed by people, not computers (even if they use software apps to help them.) His CCPM and "Theory of Constraints" are the building blocks for the Critical Chain PM functionality in Sciforma, for example.
"Safety" gets built into individual tasks in an effort to protect delivery dates in the event of unforeseen problems. Even when there are no problems, time estimates are still padded the next time - just in case. The padding also gets used up wastefully for the reasons given above. Delays are then passed on to the whole project. Statistics show that:
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CCPM works backward. Starting at the end of the project, estimates are made for each task without the extra safety padding. The estimates are made based on experience, judgment and probability of the task being accomplished within the time allotted. Some room to maneuver is then added between different projects. The effects of reducing the individual safety buffers are:
Buffers still exist in CCPM in order to provide sufficient, but not extravagant safety. There are three types:
The priority for any resource assigned to more than one task is to first complete any task directly affecting progress along the critical chain. In addition, tasks are not left incomplete. This avoids wasteful multitasking.
Critical chain project management (CCPM) offers information and insights that CPPM (critical path project management) practitioners might not otherwise get. Instead of doggedly increasing the amount of detail in the planning of tasks, which was the previous approach to tackling project delays, CCPM simplifies and streamlines. And instead of assuming that large safety buffers per task are a fatality, CCPM offers a technique to make project schedules lean and efficient by paying suitable attention to the human factor that is fundamental to performance. However, CCPM can also be used as an additional point of view for project management, rather than a replacement for CPPM methods. By multiplying the angles like this, project managers can get even better understanding and perception of their projects overall.
In particular, CCPM can bring project managers additional information about:
Whether your preference is for CCPM, CPPM or both, find out more about project management apps to suit your enterprise with this project management software infographic. Then check out the different Project management app reviews, and see how free trial versions might also accelerate your decision for the PM app that best meets your requirements.